CONSORT-Nut: A New Reporting Guideline for Nutritional Intervention Trials

Abstract

This article provides a comprehensive overview of the upcoming CONSORT extension for nutritional intervention trials (CONSORT-Nut). Aimed at researchers, scientists, and drug development professionals, it explores the critical need for standardized reporting in nutrition science. The content covers the foundational updates in the CONSORT 2025 statement, details the methodological development of the nutrition-specific extension, addresses common troubleshooting for reporting challenges, and validates the guideline's role in enhancing evidence quality. By synthesizing the latest developments from the EQUATOR Network and the Federation of European Nutrition Societies (FENS), this guide serves as an essential resource for improving transparency, reproducibility, and clinical applicability of nutrition research.

The Foundation: Understanding CONSORT 2025 and the Need for Nutrition-Specific Guidance

The CONSORT (Consolidated Standards of Reporting Trials) statement, first published in 1996 and last updated in 2010, has long been the cornerstone for ensuring transparent and complete reporting of randomized controlled trials (RCTs). In 2025, a significant update was simultaneously published in five leading medical journals (BMJ, JAMA, The Lancet, Nature Medicine, and PLoS Medicine) to account for recent methodological advancements and extensive user feedback [1] [2]. This application note details the key changes in the CONSORT 2025 statement, with a special focus on its novel open science emphasis, and provides specific protocols for its application in the context of nutritional intervention trials research.

The Evolution and Development of CONSORT 2025

The decision to update the CONSORT 2010 statement was driven by the need to reflect new evidence, methodological advancements, and feedback from end users [1]. As a "living guideline," its value would diminish over time without periodic updates [1]. The development process for CONSORT 2025 was methodologically rigorous, following the EQUATOR Network guidance for developers of health research guidelines [1]. The process involved a comprehensive scoping review of the literature and the creation of a project-specific database for empirical and theoretical evidence related to CONSORT and risk of bias in randomized trials [1] [3].

This evidence-based approach was enriched with recommendations from lead authors of key CONSORT extensions (Harms, Outcomes, Non-Pharmacological Treatment) and other related reporting guidelines like TIDieR (Template for Intervention Description and Replication) [1] [3]. Potential changes were evaluated through a large, international, online three-round Delphi survey involving 317 participants, representing diverse stakeholder groups including statisticians, systematic reviewers, trial investigators, clinicians, journal editors, and patient representatives [1]. The findings were subsequently discussed at a two-day online expert consensus meeting with 30 invited international experts, leading to the finalized checklist [1].

A significant development in this update was the closer collaboration with the SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) statement, which provides guidelines for trial protocols [1] [4]. The executive groups of SPIRIT and CONSORT decided to work together, recognizing their conceptual linkage, and ultimately published their 2025 updates simultaneously to harmonize guidance across the trial lifecycle from protocol to final publication [1] [5].

Key Updates in the CONSORT 2025 Checklist

The CONSORT 2025 statement introduces substantial modifications to its checklist, which now comprises 30 essential items [3]. The structure has been reorganized, notably with the addition of a dedicated "Open Science" section, enhancing the framework for transparent research reporting.

Table 1: Summary of Key Changes in the CONSORT 2025 Checklist

Change Type	Description	Key Examples
New Items	Seven new essential items added.	- Enhanced transparency on statistical analysis plans, funding, and conflicts of interest [6].- Requirements for data and material accessibility/sharing [6].- Patient and public involvement in all trial stages [6].
Revised Items	Three items modified for clarity and specificity.	- Clearer definitions and assessments for systematic and non-systematic harms [6].
Deleted Items	One item removed from the previous checklist.	-
Integrated Items	Incorporation of items from key extensions.	- Integration of elements from CONSORT extensions for Harms [7], Outcomes [7], and Non-Pharmacological Treatments [7] [1].
Structural Changes	Reorganization of the checklist layout.	- New "Open Science" section grouping conceptually linked items like trial registration and data sharing [1].

These updates collectively aim to address gaps in trial reporting that have been consistently documented over the past decade. The enhanced focus on statistical analysis plans, data sharing, and conflict of interest declarations directly targets elements crucial for assessing potential biases and verifying results [6]. The explicit requirement for reporting patient or public involvement acknowledges the growing importance of incorporating stakeholder perspectives into research, though this also introduces potential feasibility concerns regarding representativeness and the risk of socioeconomic selection bias [6].

The integration of items from major CONSORT extensions, particularly those concerning harms reporting (CONSORT Harms) and non-pharmacological treatments (CONSORT-NPT), is a pivotal update. This integration makes specialized reporting requirements more accessible and applicable to a wider range of trials, including complex nutritional interventions [7] [1].

Figure 1: Logical structure of key updates in the CONSORT 2025 statement, highlighting the new Open Science section and other major thematic changes.

The Open Science Focus: A New Paradigm for Trial Reporting

A cornerstone of the CONSORT 2025 update is its formalized emphasis on Open Science practices, now consolidated into a dedicated section within the checklist [1]. This reflects a paradigm shift in clinical research towards greater transparency, reproducibility, and accessibility. The open science items in CONSORT 2025 are designed to ensure that critical research artifacts are not only created but also made publicly available, facilitating independent verification and secondary analysis of trial findings [4].

Table 2: Open Science Requirements in CONSORT 2025

Checklist Item	Key Reporting Requirements	Rationale & Impact
Trial Registration (Item 2)	Registration number and registry name.	Enables identification of potential selective reporting and outcome switching by comparing the published report against the pre-specified protocol [1].
Protocol & SAP Access (Item 3)	Where and how the full trial protocol and statistical analysis plan (SAP) can be accessed.	Allows readers to critically appraise the methodology and analysis against the pre-specified plan, reducing post-hoc analysis bias [1] [4].
Data Sharing (Item 4)	Statement on whether de-identified participant data will be shared, and the mechanisms for access.	Promotes data reuse, validation of results, and inclusion in future meta-analyses, maximizing the value of collected data [6] [4].
Funding & Conflicts (Item 5)	Detailed sources of funding and declarations of conflicts of interest for all contributors.	Essential for assessing potential financial and non-financial biases that may influence the design, conduct, analysis, or interpretation of the trial [6].

The explicit requirement for a data sharing statement (Item 4) is particularly transformative. It encourages a culture where clinical trial data is recognized as a valuable asset to the broader scientific community, potentially accelerating discoveries. Furthermore, by mandating transparency on funding and conflicts of interest (Item 5), CONSORT 2025 empowers readers to make more informed judgments about the potential for bias in the reported results [6].

For nutritional researchers, adhering to these open science principles is critical. Nutritional science often involves complex interventions where methodological details—such as the specific composition of diets, nutrient bioavailability, and assessment of adherence—are paramount. Publicly sharing protocols, statistical analysis plans, and data allows for a deeper understanding of the intervention and its context, enabling more accurate interpretation and synthesis of evidence in systematic reviews.

Experimental Protocols for Implementing CONSORT 2025 in Nutrition Trials

Implementing the updated guideline requires a systematic approach, especially for nutrition research which presents unique challenges. The following protocols provide a actionable roadmap for researchers.

Protocol 1: Adherence to the CONSORT 2025 Checklist

Purpose: To ensure complete and transparent reporting of a nutritional randomized controlled trial from manuscript preparation to submission.

Workflow Steps:

• Preparatory Phase: Download the official CONSORT 2025 Checklist and the accompanying Explanation and Elaboration document from the CONSORT-SPIRIT website [7] [8]. These documents are essential for understanding the rationale and specific requirements for each item.
• Manuscript Drafting Phase: During writing, treat the checklist as an active worksheet. For each of the 30 items, explicitly document the page number(s) in the manuscript where the information is reported. Do not simply state "done"; provide the specific location.
• Nutrition-Specific Elaboration Phase: Pay particular attention to items that require nuanced reporting for nutrition trials, as outlined below.
• Peer Review Phase: Include the completed checklist with your manuscript submission. Some journals may mandate this.

Figure 2: Experimental workflow for implementing the CONSORT 2025 checklist, with a specialized phase for nutritional trial considerations.

Protocol 2: Addressing Nutrition-Specific Reporting Challenges

Purpose: To provide detailed methodologies for reporting key aspects of nutritional interventions that are often poorly reported, thereby improving the credibility and utility of nutrition RCTs.

Application Notes and Methodologies:

• Intervention Description: Utilize the TIDieR (Template for Intervention Description and Replication) checklist alongside CONSORT to describe the nutritional intervention with maximal detail [1] [9]. This includes specifying the composition of diets or supplements, procedures for preparing and delivering the intervention, the qualifications of intervenors, and the location and mode of delivery. For whole-food interventions, detail the sourcing, processing, and nutrient composition analysis.
• Outcome Definition and Justification: Pre-specify and justify the primary and secondary outcomes with a clear biological rationale. For nutritional trials, this includes providing a physiological justification for the chosen length of the intervention [10]. Outcomes should be defined with such precision that they can be unambiguously identified in systematic reviews.
• Blinding and Comparator Selection: Report the blinding status (who was blinded and how) transparently. Acknowledge the inherent difficulties of blinding in many whole-diet or whole-food trials. Justify the choice of comparator (e.g., placebo, usual care, an alternative diet) and describe it with the same level of detail as the intervention group.
• Harms Monitoring and Assessment: Adhere to the integrated CONSORT Harms guidance [7]. Pre-specify how adverse events will be collected and monitored throughout the trial. Differentiate between systematic assessment (solicited) and non-systematic assessment (spontaneously reported) of harms [6]. This is crucial for building a comprehensive safety profile of nutritional interventions.

The Scientist's Toolkit for CONSORT 2025

Table 3: Essential Research Reagent Solutions for CONSORT 2025 Implementation

Tool or Resource	Function/Purpose	Access Point
CONSORT 2025 Checklist	The core 30-item checklist of essential reporting elements for any randomized trial.	CONSORT-SPIRIT website or any of the five publishing journals (e.g., BMJ, JAMA) [2].
CONSORT 2025 Explanation & Elaboration	Provides the scientific rationale, methodological background, and examples of good reporting for each checklist item. Essential for correct implementation.	Published alongside the main statement, available via the CONSORT-SPIRIT website [7] [3].
CONSORT Flow Diagram Template	Standardized visual representation of participant enrollment, allocation, follow-up, and analysis, critical for assessing attrition and adherence to intention-to-treat principles.	Included within the CONSORT 2025 materials.
SPIRIT 2025 Statement	The companion guideline for designing and reporting trial protocols. Harmonized with CONSORT 2025 to ensure consistency from planning to publication.	CONSORT-SPIRIT website [8] [9].
TIDieR Checklist	Template for Intervention Description and Replication. A vital supplement for detailing complex nutritional interventions.	EQUATOR Network Library [7] [1].
CONSORT Extensions (e.g., Harms, NPT)	Specialized checklists for specific trial designs or interventions (e.g., non-pharmacological treatments, cluster trials).	EQUATOR Network Library; existing extensions should be used until updated versions are released [7] [6].

CONSORT 2025 in the Context of Nutrition Research

The updates in CONSORT 2025 are highly relevant to the field of nutritional science, which faces unique challenges including the complexity of interventions, the influence of background diet, and difficulties with blinding [10] [9]. The enhanced requirements for detailed intervention descriptions (supported by TIDieR), precise outcome definition, and thorough harms assessment directly address common weaknesses in the reporting of nutrition RCTs.

Furthermore, the ongoing development of a CONSORT nutrition-specific extension (CONSORT-Nut) highlights the community's recognition of these unique challenges [10] [9]. This specialized extension, anticipated for release in 2026, aims to provide additional, tailored guidance for authors to ensure rigor and reproducibility, accounting for nuances like background diet and nutritional status [10]. Until CONSORT-Nut is finalized, nutrition researchers should use the general CONSORT 2025 statement as their primary guide, while consulting existing relevant extensions (e.g., for non-pharmacological treatments) and being mindful of the specific reporting challenges in their field.

Challenges and Future Perspectives

While CONSORT 2025 represents a major step forward, its implementation presents challenges. The increased detail and new requirements, such as mandatory patient and public involvement, may raise feasibility concerns and require additional resources [6]. The harmonization with SPIRIT 2025, while beneficial, means investigators must now navigate two extensive, aligned checklists [4] [5]. Additionally, the existence of over 30 CONSORT extensions for specialized trials can create complexity, requiring authors to consult multiple documents [4].

To ensure effective adoption, the CONSORT working group recommends establishing a transition period allowing ongoing trials to use the previous version, while new trials adopt CONSORT 2025 [6]. Future efforts will also need to focus on developing standardized training for investigators, journal editors, and peer reviewers to move beyond a superficial "box-ticking" approach to a substantive understanding of the reporting standards [6] [4]. As a living guideline, CONSORT will continue to evolve, with future updates likely to further integrate with broader research transparency frameworks like the Transparency and Openness Promotion (TOP) guidelines and address the reporting of trials involving emerging technologies like artificial intelligence [4].

Randomized controlled trials (RCTs) represent the gold standard for generating clinical evidence, with the CONSORT (Consolidated Standards of Reporting Trials) statement providing essential guidance for ensuring transparent and complete reporting [11]. However, nutrition intervention trials possess unique methodological complexities that distinguish them from pharmaceutical trials and create challenges when applying standard CONSORT guidelines [12] [9]. Unlike drug trials, where investigators have full control over the intervention, nutrition trials involve participants with highly heterogeneous habitual dietary patterns that significantly influence intervention responses [13]. This heterogeneity, combined with the complex correlations between dietary components, means that substituting one food for another often results in simultaneous changes to many nutrients, creating substantial challenges for isolation of effects and accurate reporting [11] [12].

Recognizing these limitations, the Federation of European Nutrition Societies (FENS) established a working group to improve the quality and completeness of reporting for nutrition trials, initiating the development of a CONSORT extension specific to nutrition RCTs [11] [9] [13]. This article examines the unique complexities of dietary interventions and explains why specialized reporting standards are essential for advancing nutritional science.

Key Complexities of Nutrition Trials

Methodological Challenges

Nutrition trials encounter several distinct methodological challenges that complicate their design, implementation, and reporting:

• Dietary Substitution Complexity: Unlike pharmaceutical interventions where placebos can be chemically identical, dietary substitutions inevitably alter multiple nutrients simultaneously [12]. For example, replacing red meat with legumes changes not just protein source but also fiber content, micronutrient profiles, and bioactive compounds.

• Absence of True Controls: Nutrition trials frequently lack non-intervention control groups due to ethical considerations surrounding dietary recommendations, often necessitating comparison between alternative interventions rather than intervention versus no intervention [13].

• Heterogeneous Baseline Exposure: All participants have pre-existing and highly variable dietary patterns that influence their response to interventions, creating substantial background noise that must be accounted for in both design and analysis [13].

• Intervention Fidelity Variability: In trials providing dietary counseling rather than direct provision of food, fidelity to the intended intervention varies considerably between participants and across studies, introducing additional variability [12].

Reporting Inadequacies in Current Practice

Current reporting of nutrition trials often fails to address field-specific methodological approaches critical for interpretation and replication. A meta-research study of nutrition RCT protocols found significant limitations in reporting completeness when assessed against SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) and TIDieR (Template for Intervention Description and Replication) guidelines [12]. These inadequacies hinder critical appraisal and reduce the credibility and validity of nutrition research, ultimately impacting the development of evidence-based nutrition policies.

Table 1: Key Differences Between Standard RCTs and Nutrition Intervention Trials

Aspect	Standard RCTs	Nutrition Intervention Trials
Control Groups	Often placebo-controlled with identical appearance	Frequently lack true non-intervention controls; use alternative diets as comparators
Intervention Purity	Single compound with specific mechanism	Multiple simultaneous nutrient changes with potentially synergistic/antagonistic effects
Baseline Exposure	Typically minimal or no pre-existing exposure to intervention	All participants have habitual dietary exposure with high inter-individual variability
Blinding Challenges	Relatively straightforward with matching placebos	Often impossible with whole foods; challenging even with supplemented foods
Regulatory Oversight	Strict pharmaceutical regulations	Less standardized oversight frameworks

The CONSORT Extension Development Initiative

Consensus Development Process

The FENS working group employed a rigorous, multi-stage process to develop the proposed CONSORT extension for nutrition trials:

• Initial Drafting: An international working group of nutrition researchers created a preliminary 28-item checklist addition to CONSORT through iterative discussions and review of existing guidelines [13].

• Community Engagement: The proposal was presented at the International Union of Nutritional Sciences International Congress of Nutrition 2022 (IUNS-ICN 22), where refinements were elicited through World Café method discussions with participating nutrition scientists [9].

• Journal Editor Consultation: Valuable insights were gathered from surveys of journal editors, leading to the development of a potential tool specific to assess adherence to the proposed nutrition extension checklist [9].

• Pilot Testing: The proposed checklist was tested on eight diverse nutrition trials, providing evidence from real-world studies that reporting of nutrition trials can be improved with these specialized guidelines [9].

Delphi Survey for Expert Consensus

To formalize consensus, the steering committee conducted a Delphi survey with international experts from December 2023 to April 2024 [11] [13]. The survey methodology followed these key steps:

Table 2: Delphi Survey Methodology and Participation

Survey Aspect	Round 1	Round 2
Participants	38 of 46 invited experts (80% response rate)	36 of 38 first-round participants (78% of initial cohort)
Response Format	Likert scale with open-ended comments	Dichotomous (yes/no) scale with final comments section
Items Evaluated	32 proposed checklist items	29 refined checklist items
Consensus Threshold	≥80% agreement ("agree" or "strongly agree")	≥80% agreement ("yes")
Achieved Consensus	23 items (72%) reached ≥80% agreement	All 29 items (100%) reached consensus

The Delphi process achieved strong consensus without requiring a third round, demonstrating robust expert agreement on the proposed checklist items [11]. Participants represented diverse expertise including RCT design, nutrition and diet studies, maternal and child health, public health nutrition, stable isotopes, nutritional epidemiology, and various sub-specialties, ensuring comprehensive coverage of the nutrition research landscape [13].

Diagram 1: CONSORT Nutrition Extension Development Workflow. The process involved multiple stages of drafting, stakeholder engagement, and formal consensus building.

Specialized Methodological Considerations for Nutrition Trials

Feeding Trial Design and Protocol

Feeding trials, where most or all food is provided to participants, offer high precision and can provide proof-of-concept evidence for dietary interventions [14]. These trials require unique methodological considerations that differ substantially from pharmaceutical trials or behavioral nutrition studies:

• Menu Design and Development: Creating diets that precisely control nutrient composition while maintaining palatability and participant adherence requires specialized nutritional expertise and validation procedures [14].

• Diet Delivery Protocols: Standardized procedures for food preparation, packaging, distribution, and monitoring of consumption are essential for maintaining intervention fidelity but are rarely described in sufficient detail in current publications [14].

• Control Diet Design: Appropriate control diets must be carefully designed to isolate the specific nutritional component being studied, which often requires sophisticated matching of multiple nutritional parameters beyond the target nutrient [14].

Statistical and Analytical Considerations

Nutrition trials require specialized statistical approaches that address their unique complexities:

• Baseline Nutritional Status Assessment: Comprehensive assessment of participants' baseline dietary patterns and nutrient status is essential for interpreting intervention responses and understanding effect modification [13].

• Adjustment for Energy Intake: Nutritional epidemiology frequently requires adjustment for total energy intake using specialized statistical methods not typically needed in pharmaceutical trials [12].

• Multiple Comparison Considerations: The complex correlational structure of dietary data necessitates careful handling of multiple comparisons to avoid false discoveries, with transparent reporting of any statistical adjustments employed [13].

Table 3: Essential Methodology Reporting Requirements for Nutrition Trials

Methodological Aspect	Reporting Requirement	Rationale
Intervention Description	Complete specification of food composition, preparation methods, and nutrient analysis	Dietary components have complex compositions that affect bioavailability and physiological impact
Control Diet Design	Detailed description of control diet composition and how it differs from intervention beyond target component	Isolating specific nutritional effects requires understanding all dietary differences
Blinding Procedures	Description of blinding methods and assessment of blinding success where applicable	Many nutrition interventions cannot be perfectly blinded, requiring documentation of potential bias
Adherence Assessment	Comprehensive reporting of adherence measures and validation methods	Unlike pill counts, dietary adherence is multidimensional and difficult to quantify
Dietary Assessment Methods	Specification of dietary assessment tools and their validity for the specific population and nutrients	Different assessment methods have varying strengths and limitations for specific applications

Table 4: Key Research Reagent Solutions for Nutrition Trials

Tool/Resource	Function & Application	Special Considerations
Standardized Food Composition Databases	Provide nutrient profiles for menu design and analysis; essential for calculating nutrient intake	Require regular updating and validation for local food varieties and preparation methods
Validated Dietary Assessment Tools	Measure habitual intake (FFQs, 24-hour recalls), immediate consumption (food diaries), or biological exposure (biomarkers)	Each tool has specific limitations; often used in combination for comprehensive assessment
Food Provision & Preparation Protocols	Standardized procedures for food sourcing, preparation, and distribution to maintain intervention consistency	Critical for minimizing variability in nutrient content and presentation across participants
Blinding Validation Assessments	Questionnaires or tests to assess whether participants can distinguish between intervention and control diets	Particularly important when testing whole foods or diets with distinctive sensory properties
Adherence Monitoring Methods	Tools to measure compliance with dietary protocols, ranging from food diaries to biological biomarkers	Multiple complementary methods often needed to accurately capture complex dietary behaviors

Implications and Future Directions

The development of a CONSORT extension for nutrition trials represents a critical advancement for the field, addressing the unique complexities of dietary interventions that have historically challenged researchers, reviewers, and consumers of nutrition science [9]. By providing tailored guidance for reporting nutrition trials, this initiative aims to:

• Enhance Reproducibility: Standardized reporting of nutrition-specific methodological details will improve the ability to replicate and validate findings across different populations and settings [11].

• Strengthen Evidence Synthesis: More complete and consistent reporting will facilitate more meaningful meta-analyses and systematic reviews, strengthening the evidence base for nutrition policy and practice [13].

• Improve Peer Review: Journal editors and reviewers will have clearer standards for evaluating the methodological quality and completeness of nutrition trial reports [9].

• Facilitate Clinical Translation: Better reporting of intervention details, context, and limitations will enhance the ability to translate findings into clinical practice and public health recommendations [14].

The forthcoming consensus meetings will refine the 29-item checklist based on the Delphi survey results, with the goal of formal endorsement and implementation across nutrition research journals and institutions [11]. This specialized reporting guideline promises to significantly strengthen the rigor, transparency, and impact of nutrition intervention research, ultimately supporting more effective evidence-based nutrition policies and clinical recommendations.

Diagram 2: Logic Model: From Problem to Impact. The specialized CONSORT extension addresses unique nutritional trial complexities to ultimately improve evidence-based policy and practice.

The demand for evidence-based dietary guidance relies on a rigorous foundation of robust clinical trials. However, the field of nutrition science faces a significant challenge: incomplete and non-transparent reporting in randomized controlled trials (RCTs). This evidence gap undermines the reliability of the nutritional evidence base and hampers the development of effective public health guidelines. Unlike simpler pharmaceutical interventions, nutritional interventions present unique complexities including diverse intervention types (from whole foods to dietary patterns), compliance monitoring difficulties, and nutrient interactions. These complexities necessitate more comprehensive reporting standards than those required for conventional drug trials [9] [15].

Recent initiatives have recognized that generic reporting standards, such as the CONsolidated Standards Of Reporting Trials (CONSORT) statement, are insufficient for addressing the specific methodological intricacies of nutrition research. This recognition has sparked an international effort to develop nutrition-specific extensions to improve reporting completeness, transparency, and reproducibility [15]. The following sections analyze the documented shortcomings, present quantitative evidence of reporting deficiencies, and introduce structured protocols to address these critical gaps.

Documented Shortcomings and Quantitative Evidence

Systematic assessments of nutrition trial literature have identified consistent reporting gaps across multiple domains. These deficiencies limit the ability of researchers, clinicians, and policymakers to critically appraise study validity, interpret findings appropriately, and synthesize evidence in systematic reviews.

Core Reporting Deficiencies in Nutrition RCTs

The table below summarizes the most critical documentation shortcomings identified in nutritional intervention trials:

Table 1: Documented Shortcomings in Nutrition RCT Reporting

Domain	Reporting Deficiency	Impact on Evidence Base
Intervention Characterization	Incomplete description of dietary composition, nutrient analysis methods, and food source documentation [9]	Prevents accurate replication and understanding of biological mechanisms
Compliance Assessment	Failure to report methods for monitoring participant adherence and actual compliance rates achieved [9]	Undermines interpretation of null findings and dose-response relationships
Blinding Procedures	Inadequate description of blinding methods for participants, interveners, and outcome assessors [15]	Compromises assessment of potential performance and detection bias
Control Group Management	Poor documentation of control interventions and co-interventions across study arms [9]	Limits understanding of what the intervention is actually being compared against
Long-term Outcomes	Limited reporting of sustained effects beyond immediate post-intervention period [16]	Restricts understanding of durability of nutritional interventions

Quantitative Evidence of Reporting Gaps

A systematic review examining nutrition interventions in the first 1000 days of life revealed substantial limitations in the current evidence base. The analysis of 63 articles covering 20 interventions demonstrated that most trials had limited long-term follow-up and heterogeneous outcome reporting [16]:

Table 2: Quantitative Evidence of Reporting Gaps from Systematic Review

Reporting Aspect	Documented Limitation	Evidence from Literature
Follow-up Duration	Majority of interventions had follow-ups under 5 years despite focus on long-term health outcomes [16]	85% of included studies had follow-up periods ≤5 years for interventions beginning in early infancy
Outcome Reporting	Heterogeneous outcome selection and measurement methods across studies [16]	High methodological variability prevented meta-analysis in 100% of identified outcomes
Evidence Quality	Limited high-quality evidence for most health outcome domains [16]	Only 15% of outcomes rated as high-certainty evidence using GRADE methodology
Trial Design Reporting	Incomplete description of randomization, allocation concealment, and blinding procedures [15]	Over 60% of protocols reviewed had unclear or high risk of bias due to reporting gaps

These quantitative findings confirm that incomplete reporting consistently obstructs evidence synthesis and clinical application in nutrition science.

The CONSORT-Nutrition Initiative: Addressing the Evidence Gap

Development Process for Nutrition-Specific Reporting Guidelines

International collaborative efforts have emerged to address the documented shortcomings in nutrition trial reporting. The Federation of European Nutrition Societies (FENS) "Improving Standards in the Science of Nutrition" initiative has partnered with the STAR-NUT working group to develop CONSORT-Nut, a nutrition-specific extension to the CONSORT statement [15]. The development follows a rigorous methodological approach:

Figure 1: CONSORT-Nut Development Workflow

This development process incorporates international input from academics across 14 institutions in 12 countries, representing 5 continents [9]. The process has included presentation and interrogation at the International Union of Nutritional Sciences International Congress of Nutrition 2022, inputs from journal editors, and pilot testing on 8 diverse nutrition trials [9]. This comprehensive approach ensures the resulting checklist addresses the most critical reporting gaps while remaining practical for researchers.

Key Reporting Elements in the CONSORT-Nut Extension

The CONSORT-Nut extension specifically targets the unique methodological challenges of nutrition interventions:

• Intervention specificity: Detailed documentation of nutritional composition, preparation methods, and source verification
• Contextual factors: Reporting of food environment, timing of interventions, and relevant co-exposures
• Adherence measurement: Standardized reporting of compliance assessment methods and actual adherence rates
• Nutrient status baseline: Documentation of baseline nutritional status and relevant biomarkers
• Comparator descriptions: Comprehensive characterization of control conditions and dietary backgrounds

These elements address the fundamental principle that nutritional interventions cannot be adequately interpreted or replicated without comprehensive reporting of these contextual and methodological details [9] [15].

Experimental Protocols for Robust Nutrition Research

Comprehensive Nutrition Trial Implementation Workflow

Implementing high-quality nutrition trials requires meticulous attention to methodological details often overlooked in conventional trials. The following protocol provides a framework for addressing common reporting shortcomings:

Figure 2: Nutrition Trial Implementation Workflow

Detailed Methodological Guidance

Intervention Development and Characterization

• Dietary Composition Analysis: Document comprehensive nutrient profiling using validated databases (e.g., USDA FoodData Central) or direct chemical analysis when novel foods are used
• Food Source Verification: Specify suppliers, batch numbers, and quality control measures for all intervention components
• Preparation Standardization: Detail food preparation methods, cooking techniques, and storage conditions that may affect nutrient bioavailability
• Comparator Matching: For placebo-controlled trials, document matching procedures for taste, appearance, and texture while ensuring nutrient differentiation

Compliance Assessment Protocol

• Multiple Assessment Methods: Implement at least two complementary compliance measures (e.g., food diaries + biomarkers)
• Biomarker Selection: Select nutritional biomarkers specific to the intervention (e.g., plasma carotenoids for fruit/vegetable interventions, omega-3 fatty acids for fish oil interventions)
• Frequency Specification: Define assessment schedule with justification for timing relative to intervention adherence
• Quantitative Metrics: Establish predefined compliance thresholds for protocol adherence and analyze both per-protocol and intention-to-treat populations

Blinding Procedures

• Blinding Assessment: Incorporate formal tests of blinding effectiveness at study conclusion
• Blinding Documentation: Specify which parties were blinded (participants, interveners, outcome assessors, statisticians)
• Unblinding Procedures: Document circumstances and procedures for emergency unblinding

The Scientist's Toolkit: Essential Research Reagents and Materials

Table 3: Essential Research Reagents and Methodological Solutions for Nutrition RCTs

Tool Category	Specific Tools/Methods	Application in Nutrition RCTs
Dietary Assessment Tools	Validated Food Frequency Questionnaires (FFQ), 24-hour dietary recalls, digital food photography	Quantify baseline dietary intake and monitor intervention adherence and dietary changes [9]
Biomarker Assays	Mass spectrometry platforms, ELISA kits, point-of-care testing devices	Objectively verify compliance and measure nutrient status changes; examples include LC n-3 PUFA for fish oil interventions [9]
Data Collection Systems	Electronic data capture (EDC) systems, mobile health (mHealth) applications	Standardize data collection across multiple sites and enable real-time compliance monitoring
Statistical Analysis Tools	R, SAS, or Python with appropriate packages for handling missing data and adherence adjustments	Implement intention-to-treat and per-protocol analyses appropriate for nutrition trials [9]
Protocol Visualization Tools	Graphic protocol software (e.g., BioRender)	Create clear, standardized visual representations of complex nutritional interventions [17]

The documented shortcomings in nutrition RCT reporting represent a significant methodological challenge that undermines the evidence base for nutritional recommendations. The development of CONSORT-Nut, through international collaboration and evidence-based methodology, provides a promising pathway toward addressing these deficiencies. By implementing the detailed protocols and methodological solutions outlined in this application note, nutrition researchers can significantly enhance the transparency, reproducibility, and clinical utility of nutritional interventions. The scientific community must embrace these enhanced standards to strengthen the foundation of evidence-based nutrition and fulfill the field's potential to improve public health outcomes through rigorous scientific investigation.

The Federation of European Nutrition Societies (FENS) and the EQUATOR Network have established a formal collaboration to address critical gaps in the reporting quality of nutrition research. This partnership represents a strategic response to the growing recognition within the scientific community that nutrition research possesses unique methodological complexities not fully addressed by existing reporting standards for randomized controlled trials (RCTs) [18] [19]. The collaboration synergizes two complementary initiatives: the FENS "Improving Standards in Nutrition Science" working group and the EQUATOR Network's "Securing Transparency And Reproducibility in studies of NUTritional interventions (STAR-NUT)" programme [19].

The primary objective of this joint mission is to develop, validate, and disseminate a nutrition-specific extension to the Consolidated Standards of Reporting Trials (CONSORT) statement, known as CONSORT-Nut [10] [19]. This endeavor aims to enhance the transparency, reproducibility, and overall quality of reporting in nutrition intervention trials, thereby strengthening the evidence base for nutritional recommendations and public health policies. The initiative directly addresses the inherent complexities in nutrition research, including difficulties in controlling background diet, challenges with blinding, and the physiological relevance of intervention durations [10].

The Need for Nutrition-Specific Reporting Guidelines

Randomized controlled trials in nutrition face distinct methodological challenges that differentiate them from pharmaceutical trials and complicate their design, implementation, and interpretation. The FENS-EQUATOR collaboration has identified several critical areas where standard CONSORT guidelines require specialization for nutritional interventions.

Table 1: Key Challenges in Nutrition RCTs Addressed by the CONSORT-Nut Initiative

Challenge Category	Specific Issue	Impact on Evidence Quality
Intervention Complexity	Difficulty controlling background diet and nutritional status [10]	Introduces confounding variables and reduces internal validity
Methodological Limitations	Challenges with effective blinding, especially for whole foods/diet interventions [10]	Increases risk of performance and detection bias
Comparator Issues	Lack of true placebo controls for many nutritional interventions [10]	Complicates interpretation of treatment effects
Outcome Definition	Poorly defined outcomes and treatment effects [10]	Hinders comparison across studies and data synthesis
Intervention Duration	Length often not justified with respect to physiology [10]	Questions biological plausibility of findings

Incomplete reporting of methodological details presents significant obstacles for risk of bias assessments and often leads to a lower Grading of Recommendations, Assessment, Development and Evaluations (GRADE) of evidence when results are combined in systematic reviews and meta-analyses [10]. This ultimately undermines the credibility of nutrition science and impedes the translation of research findings into effective public health policies and clinical practice.

The CONSORT-Nut Development Framework

Project Structure and Governance

The CONSORT-Nut extension is being developed through a structured, multi-stage process jointly managed by FENS and EQUATOR Network representatives. The initiative is spearheaded by the Science Subgroup of the FENS Presidential Activity under Professor Philip Calder, specifically the working group on "Improving Standards in Nutrition Science" [10]. The core team includes Profs Karen Murphy, Connie Weaver, Anne Marie Minihane, Sangeetha Shyam, and Carl Lachat, led by Dr. Jessica Rigutto-Farebrother [10]. The final development stage is supported by EQUATOR methodology experts [10].

The project employs EQUATOR Network's established methodology for reporting guideline development, which incorporates systematic evidence synthesis, expert consensus, and stakeholder engagement [19]. This rigorous approach ensures that the final CONSORT-Nut checklist is both evidence-based and practically applicable across the diverse field of nutrition research.

Development Workflow and Methodological Process

The following diagram illustrates the multi-stage workflow for developing the CONSORT-Nut reporting guideline:

Key Development Activities and Status

Evidence Synthesis and Draft Proposal

The initial phase involved comprehensive literature reviews to identify and characterize reporting limitations in nutrition research [19]. This evidence informed the creation of a draft 32-item checklist extending the standard CONSORT guidelines [19] [11].

Delphi Consensus Process

A formal Delphi survey was conducted to gather feedback from a diverse panel of nutrition and health experts. The survey included 138 invited participants with representative expertise and geographical distribution [11]. The process achieved strong consensus, with 100% of the revised 29-item checklist achieving ≥80% agreement in the second round [11].

Consensus Meeting and Finalization

The project has secured funding for a consensus meeting where international experts will finalize the format and specific items for the CONSORT-Nut extension [19]. This meeting represents the final stage in the development process before official publication.

Implementation Framework for CONSORT-Nut

Adoption Strategy and Timeline

The FENS-EQUATOR collaboration has developed a comprehensive implementation strategy to ensure widespread adoption of the CONSORT-Nut guidelines across the nutrition research community. According to current projections, the consortium anticipates that scientific journals will begin implementing the CONSORT-Nut extension in 2026 [10]. This timeline is supported by positive feedback from nutrition journal editors who have expressed enthusiasm for this development [10].

Table 2: CONSORT-Nut Implementation Timeline and Key Activities

Timeline	Key Activity	Responsible Party	Output/Deliverable
2025	Final consensus meeting	FENS, EQUATOR & international experts	Finalized CONSORT-Nut checklist
Late 2025	Preparation of elaboration document	Working group with EQUATOR support	Explanation and examples for each item
2026	Journal adoption phase	Journal editors & editorial boards	Integration into author guidelines
2026-2027	Researcher training & education	FENS, EQUATOR & institutions	Webinars, workshops, online materials

Capacity Building and Training Programs

The collaboration plans to develop freely available online tools for research supervisors and lecturers throughout the nutrition higher education system to promote use of the extension throughout the trial process [10]. Additional training modalities will include targeted webinars and dedicated sessions at scientific conferences to provide practical guidance on applying the new reporting standards [10].

Research Reagent Solutions for Nutrition Trials

The following table outlines essential methodological components and their functions in conducting robust nutrition randomized controlled trials, reflecting the areas emphasized by the CONSORT-Nut initiative.

Table 3: Key Research Reagent Solutions for Nutrition Intervention Trials

Research Component	Function in Nutrition Trials	Reporting Considerations
Dietary Assessment Tools	Quantify background diet and nutritional status	Specify validation method, frequency, and timing of administration [10]
Biomarkers of Compliance	Objectively verify intervention adherence	Describe analytical methods and justification for chosen biomarkers [10]
Appropriate Comparator	Provide legitimate control for intervention	Justify choice based on physiological response and blinding feasibility [10]
Food Composition Databases	Standardize nutrient composition data	Specify database version and any modifications for local foods
Data Management Systems	Ensure data integrity throughout trial	Document cleaning procedures, blinding maintenance, and monitoring

Anticipated Impact and Future Directions

The implementation of CONSORT-Nut is expected to significantly enhance the credibility and translational potential of nutrition research. By improving the completeness and transparency of reporting, the guidelines will facilitate more accurate risk of bias assessment and increase the inclusion of nutrition trials in systematic reviews and meta-analyses [10]. This, in turn, will strengthen the evidence base for public health nutrition recommendations and food product innovation [10].

The FENS-EQUATOR collaboration represents a sustainable framework for ongoing improvement of standards in nutrition science. Beyond the CONSORT extension, the groups are also working on nutrition-specific adaptations for other key reporting guidelines, including SPIRIT (for trial protocols) and PRISMA (for systematic reviews) [19]. This comprehensive approach ensures that the entire nutrition research pipeline—from protocol development to evidence synthesis—will benefit from enhanced reporting standards.

Researchers are encouraged to follow @consort_nut for updates and attend the scheduled symposium at FENS 2025 on Thursday, 28th August 2025, for further guidance on implementing these new reporting standards [10] [19].

Inside CONSORT-Nut Development: Methodology and Practical Application

The development of reporting guidelines, such as extensions to the CONSORT (Consolidated Standards of Reporting Trials) Statement, is critical for enhancing the quality, transparency, and reproducibility of research. For specialized fields like nutritional intervention trials, this process typically follows a structured roadmap. This roadmap begins with evidence synthesis to identify reporting gaps and proceeds through a formal Delphi consensus method to establish expert agreement on guideline items. This protocol details the application of this development roadmap specifically for creating a CONSORT extension for nutritional intervention trials (CONSORT-Nut), providing researchers with a clear framework for generating robust, internationally-recognized reporting standards.

The CONSORT Statement is an evidence-based minimum set of recommendations for reporting randomized trials. It aims to facilitate the complete and transparent reporting of study methods and results [7]. Given the unique complexities inherent to different intervention types, the standard CONSORT checklist is often extended to address discipline-specific reporting needs. Nutrition research is one such field where specialized guidance is required.

Randomized controlled trials (RCTs) in nutrition are often inherently more complex than pharmaceutical trials. Challenges include the influence of background diet and nutritional status, the difficulty of effectively blinding whole foods or dietary interventions, and the frequent lack of a true placebo comparator [10]. These nuances create distinct reporting requirements not fully covered by the core CONSORT checklist. Consequently, a dedicated working group, part of the FENS (Federation of European Nutrition Societies) Presidential Activity on "Improving Standards in Nutrition Science," is spearheading the development of a CONSORT extension for nutrition trials [10]. This article outlines the definitive roadmap for this undertaking, from initial evidence synthesis to final international Delphi survey.

Experimental Protocols

Protocol 1: Preliminary Evidence Synthesis

Objective: To systematically map the existing literature and identify specific reporting weaknesses and gaps in published nutritional intervention trials that justify the need for a dedicated CONSORT extension.

• Information Gathering: Conduct a systematic scoping review of published nutritional RCTs. The review should characterize the types of reporting omissions and their frequency. For nutrition trials, this often involves identifying poorly defined outcomes, insufficient detail on the nutritional intervention (e.g., composition, delivery, compliance), and inadequate justification of intervention duration based on physiological rationale [10].
• Stakeholder Consultation: Engage in preliminary, informal consultations with a diverse group of stakeholders. This group should include nutrition researchers, biostatisticians, journal editors, clinical practitioners, and patient partners. The goal is to gather initial feedback on perceived reporting challenges and the scope of the proposed extension [20].
• Draft Item Generation: Synthesize findings from the literature review and stakeholder consultations into a preliminary list of potential items and elaborations for the nutrition-specific extension. This draft serves as the foundational document for the subsequent formal consensus process.

Protocol 2: The Delphi Consensus Method

Objective: To establish international expert consensus on the importance, clarity, and comprehensiveness of the proposed reporting items for the CONSORT-Nut extension.

The Delphi method is a structured, iterative group communication process designed to achieve a convergence of opinion on a complex topic from a panel of experts. Its key features include anonymity, iterative data collection with controlled feedback, and statistical determination of the group response [21]. The following protocol is adapted from recent successful guideline development efforts [22] [23].

• Expert Panel Recruitment:

  • Sampling: Use a purposive sampling strategy to identify and recruit an international panel of experts. The panel should include researchers, healthcare providers, policy makers, and other end-users of nutrition research [24] [23]. "Expertise" is defined as having special skill or knowledge derived from training or lived experience [22].
  • Panel Size: While there is no fixed number, a typical Delphi panel consists of 15-20 members, though larger panels are common. Recruitment should account for an expected attrition rate of 20-30% over multiple rounds [23].
  • Snowball Sampling: Allow initially recruited experts to nominate additional qualified participants to broaden the panel's diversity and reach [22].

• Delphi Process Rounds: The process typically involves multiple rounds of online surveys. A modified Delphi approach may incorporate a moderated discussion round between voting rounds [21].

  • Round 1 (Brainstorming and Initial Rating): The preliminary list of items from Protocol 1 is presented to the panel. Experts are asked to rate each item on criteria such as importance, relevance, and clarity, typically using a Likert scale (e.g., 1-5 or 1-9) [20] [23]. They are also invited to suggest new items or provide qualitative feedback on existing ones.
  • Analysis & Feedback Between Rounds: The research team analyzes the results, calculating descriptive statistics (mean, median, percentage agreement) for each item. A pre-defined consensus threshold is applied (e.g., ≥70% of experts rating an item as "important" or "very important") [24] [22]. Items that meet the consensus threshold are provisionally accepted. Items not meeting the threshold, along with newly suggested items and qualitative feedback, are carried forward to the next round. A summary of the group's responses and the panel's own previous ratings is prepared for distribution.
  • Round 2 (Refinement and Re-rating): Panelists receive the feedback report and are asked to re-rate the items that did not reach consensus in the first round, considering the group's feedback. This process allows experts to refine their opinions based on the collective judgment of the panel [21] [22].
  • Subsequent Rounds: The iterative process of rating, feedback, and re-rating continues until consensus is reached on a high proportion of items, a pre-determined number of rounds is completed, or diminishing returns are observed. Most Delphi processes achieve stability within 2-4 rounds [22] [23].

• Steering Committee: A small steering committee, comprising academics, clinicians, and methodologies, should oversee the process. This committee is responsible for reviewing results between rounds, making decisions on item wording changes, and interpreting the consensus thresholds [20].

• Final Agreement and Guideline Drafting: After the final Delphi round, all items that have met the consensus threshold are compiled into a draft checklist. This draft, along with an explanatory and elaboration document, forms the basis of the new CONSORT extension.

The logical workflow of the entire development roadmap, from inception to dissemination, is summarized in the diagram below.

Data Presentation

Effective presentation of quantitative data is essential for reporting the results of both the evidence synthesis and the Delphi process. The following tables provide structured templates for this purpose.

Table 1: Template for Presenting Frequency of Reporting Gaps Identified in Evidence Synthesis

Reporting Domain	Number of Studies Reviewed	Studies with Incomplete Reporting (n)	Studies with Incomplete Reporting (%)	Specific Common Omissions
Intervention Composition				Dose, source, processing
Background Diet				Assessment method, composition
Blinding Procedures				Description of blinding attempt
Outcome Justification				Physiological rationale for choice
Example: Comparator	100	85	85%	True placebo justification

Table 2: Template for Presenting Delphi Panel Demographics and Expertise

Characteristic	Category	Number of Experts (n)	Percentage of Panel (%)
Primary Affiliation	Academic/Research
	Healthcare Provider
	Policy Maker
	Patient Partner
Geographic Region	North America
	Europe
	Asia
	Other
Years of Experience	< 5 years
	5-15 years
	> 15 years
Area of Expertise	Nutrition Science
	Clinical Trials
	Statistics
	Journal Editing

Table 3: Template for Presenting Delphi Round 1 Results for Proposed Guideline Items

Proposed Reporting Item	Mean Importance Rating (1-9)	Panel Rating Item as 'Important' or 'Very Important' (%)	Reached Consensus (≥70%)	Qualitative Feedback Summary
Example: Detailed description of nutritional intervention source and composition	8.7	96%	Yes	Critical for reproducibility
Example: Justification for intervention duration based on nutrient physiology	8.1	88%	Yes	Links design to mechanism
Example: Method for assessing background diet	6.9	65%	No	Carry to Round 2 for re-rating
Example: Protocol for handling dietary non-compliance	7.5	92%	Yes	Essential for intention-to-treat analysis

The Scientist's Toolkit: Research Reagent Solutions

This section details the key methodological "reagents" required to execute the development roadmap successfully.

Table 4: Essential Methodological Tools for Guideline Development

Tool / Resource	Category	Function in Development Roadmap	Implementation Example
EQUATOR Network [7]	Knowledge Repository	Provides access to existing reporting guidelines (like CONSORT) and methodological guidance for developers.	Consulting the EQUATOR network library is the first step to understand best practices in guideline development.
Systematic Review Software (e.g., Covidence, Rayyan)	Evidence Synthesis	Facilitates the screening and data extraction phases of the preliminary evidence synthesis by enabling collaborative, efficient management of large volumes of literature.	Used in Protocol 1 to manage identification of reporting gaps in nutritional trials.
Online Survey Platform (e.g., LimeSurvey, SurveyMonkey) [20]	Delphi Administration	Hosts the iterative rounds of Delphi surveys, allowing for anonymous data collection, complex question routing, and automated data export for analysis.	The platform is used to administer Rounds 1, 2, etc., of the Delphi process in Protocol 2.
Delphi Method Protocols [21] [22] [23]	Methodological Framework	Provides the structured, iterative process for achieving expert consensus, including definitions of consensus, round structures, and feedback mechanisms.	The entire Protocol 2 is built upon the established principles of the Delphi method.
Statistical Software (e.g., R, SPSS, Excel)	Data Analysis	Used to calculate descriptive statistics (means, medians, percentages) for each Delphi round to quantitatively determine group consensus levels.	Analyzing Likert-scale responses from each Delphi round to identify items meeting the ≥70% consensus threshold.
Project Steering Committee	Governance & Expertise	A group of experts who oversee the process, make decisions on item modifications between rounds, and ensure the scientific rigor of the final output.	The committee reviews quantitative and qualitative results after each Delphi round to guide the process for the subsequent round [20].

The structured roadmap from evidence synthesis to international Delphi consensus provides a rigorous and transparent methodology for developing specialized reporting guidelines. The forthcoming CONSORT-Nut extension, developed through this very process, is anticipated to address critical reporting gaps in nutritional intervention trials. By mandating more detailed reporting on intervention characteristics, background diet, and outcome justification, the extension will enhance the reliability and usability of nutrition research. This will, in turn, improve the quality of systematic reviews, strengthen the evidence base for public health policy and product innovation, and ultimately increase the credibility of the entire nutrition science field [10]. The final publication and dissemination of the CONSORT-Nut guideline is projected for implementation in scientific journals by 2026 [10].

The CONSORT (Consolidated Standards of Reporting Trials) statement is an evidence-based minimum set of recommendations for reporting randomized controlled trials (RCTs) [25]. It stands for the COnsolidated Standards Of Reporting Trials and is intended to facilitate the complete and transparent reporting of study methods and findings, which is critical for critical appraisal and interpretation of trial results [25]. First published in 1996, then updated in 2001 and 2010, the most recent CONSORT 2025 statement has been published to account for recent methodological advancements and feedback from end users [25] [26]. Well designed and properly executed randomised trials are considered the most reliable evidence on the benefits of healthcare interventions, but incomplete reporting may be associated with biased estimates of intervention effects [25].

Reporting guidelines like CONSORT define a minimum set of information required when reporting medical research to ensure its usefulness [27]. However, nutrition research provides evidence to support public health policies, advances in clinical practice, and improved quality of life for patients, and reporting diet- and nutrition-related RCTs requires particular attention to field-specific methodological aspects [27]. Unlike highly regulated drug trials, diet and nutrition-related RCTs are not subject to oversight by regulatory agencies, which might explain the lack of reporting of essential details in papers describing non-regulated RCTs [12]. The available reporting guidelines were not specifically designed for nutrition or diet-related RCTs, creating a significant gap in research reporting standards [12]. This gap has led to the development of a nutrition-specific extension of the CONSORT guidelines to address the unique methodological complexities of nutritional intervention trials [10].

The Need for Nutrition-Specific Reporting Guidelines

Methodological Complexities in Nutrition Research

Randomized controlled trials in nutrition are often inherently more complex than pharmaceutical trials due to several unique challenges. The influence of background diet and nutritional status is almost impossible to control, or sometimes even measure effectively [10]. Nutrition RCTs, particularly whole foods/diet and eating behavior interventions, are also difficult to blind, and available comparators do not always provide a true placebo [10]. These complexities create particular reporting challenges that generic CONSORT guidelines cannot adequately address.

Feeding trials, in which most or all food is provided, offer high precision and can provide proof-of-concept evidence that a dietary intervention is efficacious [14]. They can better evaluate the effect of known quantities of foods and nutrients on physiology, but they come with additional methodological complexities not encountered in pharmaceutical trials [14]. These trials call for a variety of unique methodological considerations, not least of which relate to the design and delivery of diets to participants, encompassing both domiciled and non-domiciled feeding trials [14].

Current Reporting Gaps in Nutrition Literature

Several studies have identified significant reporting gaps in current nutrition trial literature. A systematic review of RCTs assessing the quality of reporting in RCTs of dietetic interventions in primary care found that none of the 27 included RCTs reported all CONSORT items, with a median of 11.5 of the 28 items completely met [27]. The items most often not reported were "a description of where the full protocol can be accessed (96%)," "registry number and name of trial registry (85%)," "mechanism used to implement the random allocation sequence (81%)," and "who generated the random allocation sequence, enrolled participants and assigned participants (81%)" [27].

There remain gaps in reporting, particularly concerning outcomes that tend to be poorly defined, especially with respect to intended treatment effects and a length of intervention justified with respect to physiology and the nutritional intervention under study [10]. Full methodological detail is often absent in reports, which makes risk of bias assessments challenging, leading to an overall lower GRADE of evidence when results are combined in systematic reviews and meta-analyses [10]. This reporting insufficiency limits the ability to draw nuanced and robust conclusions from nutrition data and hampers the translation of findings into public health policy and food product innovation [10].

The CONSORT 2025 statement introduces substantial changes to the previous guideline, with a restructuring of the checklist to focus on open science principles [26]. The development process involved a scoping review of the literature, creation of a project-specific database of empirical and theoretical evidence related to CONSORT, a large international online Delphi survey involving 317 participants, and a two-day online expert consensus meeting of 30 invited international experts [25]. This rigorous development process ensures that the updated guideline reflects both methodological advancements and the practical needs of end users.

The CONSORT 2025 statement has made substantive changes to the CONSORT checklist, including adding seven new checklist items, revising three items, deleting one item, and integrating several items from key CONSORT extensions [25]. The statement consists of a 30-item checklist of essential items that should be included when reporting the results of a randomised trial and a diagram for documenting the flow of participants through the trial [25]. To facilitate implementation of CONSORT 2025, an expanded version of the checklist with bullet points eliciting critical elements of each item has also been developed [25].

Table 1: Key New Additions in CONSORT 2025 Statement

New Item	Description	Relevance to Nutrition Research
Patient and public involvement	How patients and/or the public were involved in the design, conduct, and reporting of the trial	Crucial for ensuring interventions are acceptable and feasible in real-world settings
Sharing of data	Where and how individual de-identified participant data, statistical and other materials can be accessed	Enhances transparency and enables secondary analyses of nutrition trial data
Harms	How harms (unwanted effects of an intervention) were defined and assessed	Important for documenting unintended consequences of dietary interventions
Intervention delivery	How intervention and comparator were actually administered, including associated care during trial	Critical for understanding real-world implementation of complex dietary interventions

The CONSORT-Nutrition Extension: Development and Scope

Development Process and Timeline

The development of a nutrition extension of the CONSORT reporting guidelines for RCTs has been spearheaded by the Science Subgroup of the FENS (Federation of European Nutrition Societies) Presidential Activity under Prof Philip Calder, "Improving Standards in Nutrition Science" [10]. This initiative emerged in response to an increased recognition of need within the nutrition research community [10]. The working group is comprised of Profs Karen Murphy, Connie Weaver, Anne Marie Minihane, Sangeetha Shyam and Carl Lachat, and led by Dr Jessica Rigutto-Farebrother [10]. The final stage of the extension development has been supported by the EQUATOR Network, an international initiative that seeks to improve the reliability and value of medical research literature by promoting transparent and accurate reporting of research studies [10].

The development process follows the EQUATOR Network guidance for developers of health research reporting guidelines, which emphasizes rigorous methodology including systematic reviews, Delphi surveys, and consensus meetings [25]. The nutrition extension working group has indicated that editors of nutrition journals are enthusiastic about this development, and once the extension is finalized, they will work with journals to promote its adoption, with implementation hoped for in 2026 [10]. Following the release of the extension, the working group envisages the production of online freely available tools that can be used by research supervisors and lecturers throughout the nutrition higher education system to promote the use of the extension throughout the trial process [10].

Scope and Focus Areas

The CONSORT-nutrition extension aims to provide additional support for authors of nutrition trial reports, beyond what is provided by the general CONSORT guidelines, to ensure that sufficient detail is included for rigor and reproducibility [10]. The extension will address the nuances specific to nutrition trials, with consideration to the unique methodological challenges previously identified [10]. While the complete set of 28 nutrition-specific recommendations is still under development, the scope will likely cover several key areas specific to nutrition research.

The extension will particularly focus on aspects of trial reporting where current guidelines are insufficient for nutrition studies. This includes detailed guidance on reporting dietary assessment methods, characterization of food-based interventions, description of comparator interventions, measurement of adherence, assessment of background diet, and handling of complex dietary patterns [27] [10]. The extension will also likely address specific challenges in blinding of dietary interventions, standardization of dietary composition, and reporting of nutrient bioavailability considerations.

Detailed Methodological Protocols for Nutrition Trials

Protocol Development for Diet and Nutrition RCTs

Well-written, detailed protocols allow prospective assessment of RCT methods and support scientific integrity, ethical standards, safety and retrospective validation of study methods and findings [12]. Protocols aim to describe all planned research steps comprehensively and are the key document bounding the ethical principles for medical research with human subjects [12]. The SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) reporting guideline establishes a minimum set of items to be reported in any RCT protocol, while the TIDieR (Template for Intervention Description and Replication) reporting guideline was developed to improve the reporting of interventions in RCT protocols and results papers [12].

For diet and nutrition-related RCTs, protocols should include specific elements that address the unique aspects of nutritional interventions. This includes detailed description of dietary intervention composition, methods for delivering dietary interventions, assessment of participant adherence, measurement of background diet, and consideration of nutrient-nutrient interactions [14] [12]. The protocol should also specify how dietary data will be collected, processed, and analyzed, including any specialized nutritional assessment tools or laboratory methods that will be employed [27].

Feeding Trial Methodology

Feeding trials, in which most or all food is provided to participants, represent a specific type of nutrition research with particular methodological requirements. These trials offer high precision and can provide proof-of-concept evidence that a dietary intervention is efficacious and can better evaluate the effect of known quantities of foods and nutrients on physiology [14]. However, they come with additional methodological complexities that must be carefully addressed in both protocol development and final reporting.

Table 2: Key Methodological Considerations for Feeding Trials

Methodological Aspect	Protocol Requirements	Reporting Standards
Menu design and development	Stepwise process for menu design, development, validation	Detailed description of foods used, nutrient composition, preparation methods
Intervention delivery	Procedures for food provision, storage, preparation	Adherence to planned intervention, modifications required during trial
Control diet design	Appropriate control conditions, blinding strategies	Composition of control diet, success of blinding procedures
Participant monitoring	Methods for assessing adherence, compliance metrics	Quantitative adherence data, participant retention strategies
Safety monitoring	Procedures for identifying and documenting adverse events	Harms data specific to dietary intervention, unexpected consequences

A comprehensive summary of recommendations for design and conduct of feeding trials includes defining the study population to maximize retention, safety, and generalizability of findings; recommendations for design of control interventions and optimizing blinding; and specific considerations for clinical populations [14]. A detailed stepwise process for menu design, development, validation, and delivery should also be implemented to ensure methodological consistency and execution of high-quality feeding trials [14].

Core Reporting Recommendations for Nutrition Trials

Intervention Description and Delivery

Complete description of nutritional interventions is essential for both interpretation of results and replication of studies. The TIDieR checklist provides a framework for reporting interventions, but nutrition trials require additional specificity for dietary interventions [12] [27]. Key elements that should be reported include:

• Complete characterization of intervention foods or diets: Including specific foods used, preparation methods, nutrient composition, and any processing techniques employed.
• Details of intervention delivery: How the intervention was delivered to participants (e.g., provision of all foods, dietary advice, food vouchers), frequency of contact, and methods for ensuring adherence.
• Comparator interventions: Detailed description of control or comparison conditions, including how these were designed to isolate the specific effects of the nutritional intervention of interest.
• Modifications during trial: Any changes to the intervention during the trial period, with rationale for these modifications.

For feeding trials, additional details should include the specific procedures for food preparation, quality control measures, and methods for ensuring consistent composition throughout the trial period [14]. The template for intervention description and replication (TIDieR) provides comprehensive guidance on these elements, but nutrition-specific elaboration is needed for optimal reporting [25] [27].

Dietary Assessment and Outcome Measurement

Nutrition trials employ a variety of dietary assessment methods, each with specific reporting requirements. The choice of assessment method should be justified, and the implementation details thoroughly described:

• Dietary assessment methods: Specific instruments used (e.g., food frequency questionnaires, 24-hour recalls, food records), frequency of administration, and validation information for the specific population.
• Biochemical assessment: Details of biological sample collection, processing, storage, and analytical methods, including quality control procedures.
• Nutritional status biomarkers: Specification of biomarkers used, their validation as indicators of nutritional status or intake, and laboratory methods employed.
• Clinical outcomes: Definition of nutrition-relevant clinical outcomes, methods for assessment, and timing of measurements.

Outcomes in nutrition trials are often poorly defined, particularly with respect to intended treatment effects and a length of intervention justified with respect to physiology and the nutritional intervention under study [10]. Clear definition of primary and secondary outcomes, including the rationale for their selection and the timing of assessment, is essential for interpreting trial results [27].

Implementation and Adherence Strategies

Adherence Assessment in Nutrition Trials

Assessment and reporting of participant adherence to nutritional interventions presents unique challenges compared to pharmaceutical trials. The CONSORT-nutrition extension will likely provide specific guidance on:

• Methods for measuring adherence: Direct and indirect measures of adherence specific to different types of nutritional interventions (e.g., biological biomarkers, food records, returned food containers in feeding studies).
• Reporting of adherence rates: Quantitative data on adherence throughout the trial period, not just simple statements about overall adherence.
• Strategies to enhance adherence: Specific methods used to promote and maintain adherence to the dietary intervention, with assessment of their effectiveness.
• Impact of adherence on outcomes: Analysis of how adherence levels affected intervention outcomes, including per-protocol or adherence-adjusted analyses where appropriate.

Unlike drug trials where pill counts or plasma drug levels can provide objective adherence measures, nutrition interventions often rely on self-reported dietary intake, which is subject to various measurement errors and biases [14]. The reporting of adherence should acknowledge these limitations and employ multiple assessment methods when possible.

Data Sharing and Reproducibility Practices

The CONSORT 2025 statement includes a new item on sharing of data, specifying where and how individual de-identified participant data, statistical and other materials can be accessed [26]. For nutrition trials, this has particular importance given the complexity of dietary data and the potential for secondary analyses. Specific considerations include:

• Sharing of dietary assessment data: Protocols for making dietary intake data available while protecting participant confidentiality.
• Food composition databases: Specification of the food composition tables or databases used to calculate nutrient intakes, including version information.
• Analysis code: Sharing of statistical code for deriving dietary patterns or processing nutritional data.
• Intervention materials: Availability of detailed menus, recipes, or food products used in the intervention.

A survey of a random sample of 149 biomedical articles published between 2015 and 2017 found that only 18.3% discussed publicly available data [27]. Similarly, an automated assessment of all PubMed Central articles estimated that in 2020, overall 15% of articles had a data-sharing statement and 3% had a code-sharing statement [27]. The nutrition research community has an opportunity to advance transparency by adopting more rigorous data sharing practices.

Table 3: Research Reagent Solutions for Nutrition Trials

Tool Category	Specific Tools/Methods	Application in Nutrition Research
Dietary Assessment Tools	24-hour recalls, Food Frequency Questionnaires, Food records, Dietary history	Assessment of habitual intake, monitoring of intervention adherence, evaluation of background diet
Biochemical Assessment	Nutrient biomarkers, Metabolomic profiling, Micronutrient analysis	Objective verification of intake, assessment of nutritional status, evaluation of metabolic responses
Dietary Intervention Tools	Controlled feeding facilities, Food provision systems, Recipe standardization	Delivery of precisely defined dietary interventions in feeding trials
Data Analysis Resources	Nutrition-specific statistical packages, Food composition databases, Dietary pattern analysis tools	Analysis of complex dietary data, adjustment for energy intake, derivation of dietary patterns
Adherence Monitoring	Biological markers, Food photography, Smartphone applications	Objective and subjective measures of intervention adherence in free-living populations

Future Directions and Implementation Planning

Training and Education Initiatives

The successful implementation of the CONSORT-nutrition extension will require comprehensive training and education for the nutrition research community. The working group has planned several initiatives to support this implementation:

• Online freely available tools that can be used by research supervisors and lecturers throughout the nutrition higher education system to promote the use of the extension throughout the trial process [10].
• Webinars and conference sessions to provide guidance on applying the nutrition-specific reporting guidelines [10].
• Integration into graduate curricula to ensure that the next generation of nutrition researchers is trained in these reporting standards from the beginning of their research careers.

These educational resources will be essential for ensuring that the guidelines are understood and correctly applied by researchers designing, conducting, and reporting nutrition trials. The working group recognizes that simply publishing guidelines is insufficient; active dissemination and education are necessary for successful implementation.

Journal Adoption and Policy Implications

The adoption of the CONSORT-nutrition extension by scientific journals is critical for its successful implementation. The working group has indicated that editors of nutrition journals are enthusiastic about this development, and they will work with journals to promote adoption with implementation hoped for in 2026 [10]. Journal adoption typically involves:

• Revision of author guidelines to require adherence to the CONSORT-nutrition extension for relevant trials.
• Training of editors and reviewers to appropriately evaluate manuscripts against the reporting standards.
• Implementation of checks during manuscript review to ensure completeness of reporting according to the guidelines.

Through the use of dedicated reporting guidance, authors can attest to their completeness of reporting with consideration to the nuances specific to nutrition trials [10]. This will increase the inclusivity of nutrition RCTs in systematic reviews, improve risk of bias rating, and increase the potential to include data in meta-analyses [10]. As a result, the ability to draw nuanced and robust conclusions from nutrition data will be improved, alongside an enhanced confidence to translate findings into public health policy and food product innovation [10].

Randomized Controlled Trials (RCTs) represent the gold standard for evaluating intervention efficacy, but their value depends entirely on the completeness and transparency of their reporting [28]. Inadequate reporting of nutrition data can hinder the success of nutrition health policies and evidence-based dietary recommendations [11]. The Consolidated Standards of Reporting Trials (CONSORT) statement provides essential guidance for reporting RCTs and is required by most journals today [11]. However, nutrition trials present unique complexities not adequately addressed by generic CONSORT guidelines [10].

Nutritional interventions are inherently more complex than pharmaceutical trials because the influence of background diet and nutritional status is almost impossible to control completely [10]. Additionally, whole foods/diet and eating behavior interventions are difficult to blind, and available comparators do not always provide a true placebo [10]. These fundamental differences necessitate specialized reporting standards to ensure that nutrition research can be properly evaluated, replicated, and translated into effective public health policy.

A Federation of European Nutrition Societies (FENS) working group was created to improve quality and completeness of reporting of nutrition trials, recognizing that reporting of nutrition interventions requires a more tailored approach [11]. This initiative has progressed through a Delphi expert consensus survey, development of a proposal for a CONSORT extension specific to nutrition RCTs, and plans for final implementation anticipated in 2026 [11] [10]. This document outlines the critical reporting elements specifically for intervention description, dietary assessment, and adherence measurement within this evolving framework.

Intervention Description: Beyond Generic Reporting

Precise description of nutritional interventions is fundamental to their replication and implementation in different populations and settings. The standard CONSORT guidelines require description of interventions for each group with sufficient details to allow replication [28], but nutritional interventions demand greater specificity.

Key Elements for Comprehensive Intervention Reporting

Formulation and Composition: For supplemental interventions, researchers must report exact chemical forms of nutrients, dosage forms, manufacturers, and specific product names. For whole food-based interventions, detailed descriptions should include food sources, varieties, cultivation methods when relevant, processing methods, preparation techniques, and nutrient composition data derived from chemical analysis or food composition databases.

Temporal Patterns and Delivery: Reporting must extend beyond simple dosage to include timing of administration in relation to meals, seasonal timing for interventions affected by food availability, duration of the intervention with physiological justification for the chosen timeframe, and frequency of administration.

Control Conditions: The rationale for selection of control interventions must be explicitly stated, including details of placebo composition and validation of blinding efficacy when applicable, or description of habitual diet modifications for active control groups.

Table 1: Essential Elements for Nutritional Intervention Description

Reporting Category	Specific Elements to Report	Rationale
Formulation	Chemical forms, food sources, processing methods, preparation techniques	Affects bioavailability and physiological impact
Composition	Nutrient analysis method, complete nutrient profile, bioactive compounds	Enables accurate replication and understanding of mechanisms
Dosage & Timing	Daily amount, administration schedule, relation to meals, duration	Impacts compliance, metabolic processing, and effectiveness
Control Condition	Placebo composition, blinding validation, comparator diet details	Critical for assessing trial validity and effect size interpretation

Dietary Assessment Methods: Technical Protocols

Accurate assessment of dietary intake enables understanding of diet effects on human health and disease and informs nutrition policy [29]. However, dietary exposures are notoriously difficult to measure accurately due to both random and systematic measurement error [29]. The choice of assessment method depends on the research question, study design, sample characteristics, and sample size.

Major Dietary Assessment Methodologies

24-Hour Dietary Recall (24HR) The 24HR assesses an individual's intake over the previous 24 hours through interviewer-administered or automated self-administered protocols [29]. The Automated Self-Administered 24-hour recall (ASA-24) system reduces interviewer burden and costs while allowing participants to respond at their own pace [29].

Protocol Implementation:

• Administration: Conduct multiple recalls on non-consecutive, random days, including both weekdays and weekends to account for day-to-day variation.
• Probing Technique: Use standardized probes for food preparation methods, additions after preparation (condiments, spices), and time of eating occasions.
• Analysis: Convert reported foods to nutrients using standardized food composition databases.
• Statistical Adjustment: Apply appropriate statistical methods to account for within-person variation and estimate usual intake when multiple recalls are collected [29].

Advantages: Does not require literacy; captures wider variety of foods than FFQs; random administration reduces reactivity; can be used in physically disabled populations. Limitations: Relies on memory; requires multiple administrations to estimate usual intake; expensive for large sample sizes; interviewer-administered versions require extensive training.

Food Frequency Questionnaires (FFQ) FFQs assess usual intake over extended periods (typically months to a year) by querying frequency of consumption of specific food items [29]. They can be quantitative, semi-quantitative, or qualitative, with semi-quantitative versions being most common in nutrition research [29].

Protocol Implementation:

• Questionnaire Selection: Use validated, population-specific instruments that have been tested for the nutrients and foods of interest.
• Portion Size Assessment: Include portion size estimation aids (photographs, household measures) or use a qualitative approach assuming standard portions.
• Administration: Typically self-administered, but interviewer-administered versions can be used for low-literacy populations.
• Analysis: Convert frequency responses and portion sizes to nutrient intakes using specialized analysis software linked to food composition databases.

Advantages: Cost-effective for large sample sizes; designed to capture habitual intake; enables ranking of individuals by nutrient exposure. Limitations: Limited by predefined food lists; less precise for absolute intake measurement; requires literacy and cognitive ability to complete; may create participant burden.

Food Records Food records involve comprehensive recording of all foods, beverages, and supplements consumed during a designated period, typically 3-4 days [29]. Foods can be weighed, measured, or estimated, with training significantly enhancing accuracy [29].

Protocol Implementation:

• Participant Training: Provide detailed instruction on description of foods, portion estimation, and timely recording.
• Recording Period: Typically 3-4 days, as participant burden causes decline in quality with longer recording periods.
• Monitoring: Review records for completeness and clarity, with follow-up for missing information.
• Analysis: Convert foods and portions to nutrients using food composition databases.

Advantages: Does not rely on memory when completed contemporaneously; provides detailed dietary pattern information. Limitations: High participant burden; requires literate and motivated population; reactivity (changing diet for ease of recording or social desirability) is a significant concern.

Table 2: Comparison of Major Dietary Assessment Methods

Method	Time Frame	Primary Use	Strengths	Limitations
24-Hour Recall	Short-term (24-hour period)	Total diet assessment; population monitoring	Doesn't require literacy; reduces reactivity; captures diverse foods	Relies on memory; multiple administrations needed; costly
Food Frequency Questionnaire	Long-term (months to year)	Habitual diet assessment; large epidemiological studies	Cost-effective for large samples; ranks individuals by intake	Limited food list; less precise for absolute intake
Food Record	Short-term (typically 3-4 days)	Detailed intake analysis; metabolic studies	Doesn't rely on memory; detailed data	High participant burden; reactivity concerns
Screening Tools	Variable (often 1 month-1 year)	Specific nutrients or food groups	Rapid; low burden; cost-effective	Limited scope; population-specific validation required

Biomarkers for Validation of Dietary Assessment

Recovery biomarkers represent the most rigorous means to evaluate accuracy of self-reported dietary assessment because the majority of what is consumed is "recovered" [29]. Currently, recovery biomarkers only exist for energy (doubly labeled water), protein (urinary nitrogen), sodium, and potassium (urinary excretion) [29]. Concentration biomarkers, such as plasma carotenoids for fruit and vegetable intake or fatty acid profiles for specific fats, provide additional objective measures of intake but do not permit quantitative assessment of absolute intake levels.

Adherence Measurement: Multidimensional Assessment

Adherence measurement in nutrition trials requires multiple complementary approaches, as no single method provides a complete picture of compliance with dietary interventions.

Key Protocols for Adherence Assessment

Biomarker Analysis: Collect biological samples (blood, urine, adipose tissue) appropriate for the intervention nutrients at baseline and follow-up. Analyze for specific nutrients or metabolites that reflect intake of intervention foods or nutrients. Compare changes in intervention and control groups to assess compliance.

Dietary Adherence Metrics: Calculate adherence scores based on target dietary patterns (e.g., Mediterranean diet scores, DASH diet scores). For supplement interventions, use pill counts, returned supplement inventories, or electronic monitoring devices. For food provision studies, monitor pickup or consumption of provided foods.

Novel Digital Methods: Utilize smartphone applications for real-time dietary recording with image-assisted food identification. Implement electronic food packaging monitoring for objective consumption tracking. Apply machine learning algorithms to identify dietary patterns from digital food records.

Integrated Reporting Workflow

The relationship between intervention description, dietary assessment, and adherence measurement represents an integrated system that should be reported comprehensively in nutrition trials. The following diagram illustrates the logical workflow and interrelationships between these critical reporting elements:

Table 3: Research Reagent Solutions for Nutritional Trial Reporting

Tool Category	Specific Tools/Measures	Primary Function	Implementation Considerations
Dietary Assessment Platforms	ASA-24 (Automated Self-Administered 24-hr Recall)	Standardized 24-hour recall administration	Free resource; reduces interviewer burden; may not be feasible for all populations
Biomarker Assays	Doubly labeled water, urinary nitrogen, circulating nutrients	Objective verification of intake and compliance	Costly; requires specialized laboratory facilities; specific to limited nutrients
Adherence Metrics	Pill counts, dietary pattern scores, biomarker changes	Quantification of intervention compliance	Multi-method approach recommended; should be pre-specified in statistical analysis plan
Food Composition Databases	USDA FoodData Central, country-specific databases	Conversion of food intake to nutrient values	Should match study population; consider nutrient variability in foods
Statistical Packages	NHLBI's %MENU, PC-SIDE, R packages	Accounting for within-person variation in intake	Essential for estimating usual intake from short-term instruments

The development of a CONSORT extension specific to nutrition trials represents a critical advancement for the field [11] [10]. Through use of dedicated reporting guidance, authors can ensure sufficient detail is included for methodological rigor and reproducibility, with consideration to the nuances specific to nutrition trials [10]. This will increase the inclusivity of nutrition RCTs in systematic reviews, improve risk of bias ratings, and enhance the potential for data inclusion in meta-analyses [10]. As a result, the ability to draw nuanced and robust conclusions from nutrition data will be improved, alongside enhanced confidence to translate findings into public health policy and food product innovation [10]. Researchers should anticipate formal adoption of these standards by scientific journals beginning in 2026 and should incorporate these detailed reporting elements for intervention description, dietary assessment, and adherence measurement in current trial planning and reporting.

The CONSORT-Nut initiative represents a critical advancement in nutritional science, providing a tailored extension of the Consolidated Standards of Reporting Trials (CONSORT) statement specifically for randomised controlled trials (RCTs) of nutritional interventions [30] [31]. This development addresses the unique methodological challenges and reporting gaps that have persistently hampered the field of nutrition research. As noted by Dr. Michael Schlüssel, the project lead, the inspiration for CONSORT-Nut emerged from the recognition that publications in nutritional sciences are often so heterogeneous in their reporting methods that comparing studies becomes practically impossible [31].

The fundamental rationale behind CONSORT-Nut stems from the complex nature of nutritional interventions, which differ significantly from pharmaceutical trials in several key aspects. Unlike drugs, nutrients are consumed as part of complex foods and dietary patterns, creating substantial challenges in measurement, control, and interpretation [31]. These challenges are compounded by cultural, religious, and socio-economical factors that influence dietary behaviors across different populations. The CONSORT-Nut guideline aims to enhance the transparency, completeness, and accuracy of reporting for nutrition RCTs, thereby enabling proper critical appraisal and facilitating the implementation of evidence-based nutritional interventions in clinical practice and public health policy [31].

Key Components of the CONSORT-Nut Guideline

Development and Consensus Process

The development of CONSORT-Nut has followed a rigorous, evidence-based, and consensus-driven methodology [30] [31]. The process began with comprehensive literature reviews to identify types of nutritional interventions studied over the past decade and to appraise the reporting completeness of these publications [31]. This foundational work informed the creation of a preliminary checklist, which subsequently underwent a structured Delphi consensus process involving a wide range of stakeholders.

A recent Delphi survey gathered opinions from nutrition and health experts across multiple geographies and areas of expertise [11]. The survey employed a Likert scale with comments for the initial 32-item proposal in the first round, followed by a dichotomous scale for the refined 29-item proposal in the second round. With a consensus threshold set at ≥80%, 23 items (72%) achieved agreement in the first round, and 100% of items reached consensus in the second round, resulting in a final 29-item checklist specific to reporting nutrition RCTs [11]. This robust consensus-building process ensures that the guideline reflects the collective expertise of the international nutrition research community.

Nutrition-Specific Reporting Items

CONSORT-Nut addresses several critical aspects unique to nutrition intervention research that are not adequately covered by the standard CONSORT statement. The guideline provides structured reporting standards for key methodological challenges in nutrition trials, including:

• Dietary assessment methodologies: Specific guidance on reporting the tools and methods used to assess dietary intake, including their validity and reliability in the study context [31].

• Intervention description and standardization: Detailed requirements for describing the composition, delivery, and monitoring of nutritional interventions, with particular attention to complex dietary patterns and whole-food interventions [31].

• Control group characterization: Enhanced specifications for documenting the nature and composition of control conditions, including placebos in supplementation trials or comparison diets in behavioral interventions [31].

• Nutrient replacement considerations: Guidance on reporting what participants are not consuming when increasing intake of specific foods or nutrients, acknowledging that dietary changes typically involve substitutions rather than simple additions [31].

• Adherence measurement: Standards for reporting how adherence to the nutritional intervention was assessed, including biomarkers when applicable, and how adherence data were incorporated into the analysis [31].

Table 1: Core Development Phases of CONSORT-Nut

Phase	Description	Key Activities	Status
Background Research	Literature appraisal and evidence synthesis	Identification of reporting limitations in nutrition intervention research; compilation of evidence from literature reviews	Completed [31]
Stakeholder Engagement	Gathering expert feedback on preliminary findings	Delphi surveys with international nutrition and health experts; consensus building on checklist items	Completed (2 rounds, 36 participants) [11]
Recommendation Finalization	Development of final reporting guideline	Pilot testing with researchers; refinement based on feedback; creation of good reporting examples	In progress [31]
Dissemination & Implementation	Guideline publication and promotion	Development of STAR-NUT website; social media dissemination; partnership with nutrition societies	Planned [31]

Application Notes: Integrating CONSORT-Nut into the Research Workflow

Pre-Trial Planning Phase

The effective implementation of CONSORT-Nut begins during the earliest stages of research conceptualization and protocol development. Researchers should utilize the CONSORT-Nut checklist as a foundational framework when designing their trials, rather than treating it as a post-hoc reporting requirement. This proactive approach ensures that all necessary methodological considerations are addressed before participant recruitment begins, thereby enhancing both study quality and future reporting completeness.

During the protocol development stage, research teams should specifically address how they will document and standardize their nutritional intervention, including detailed descriptions of dietary assessment methods, portion control strategies, and adherence monitoring protocols [31]. Additionally, researchers should carefully consider what their intervention group is potentially not consuming when increasing intake of specific foods or nutrients, as these dietary substitutions can significantly impact the interpretation of study findings [31]. Establishing clear procedures for collecting these data during the planning phase is essential for generating meaningful results.

Trial Conduct and Data Collection Phase

Throughout trial implementation, researchers should systematically document all aspects of intervention delivery, adherence monitoring, and any protocol modifications using the CONSORT-Nut framework as a guide. Particular attention should be paid to the detailed characterization of the intervention, including any challenges in standardization across different settings or participant groups.

For complex dietary interventions, researchers should implement robust processes for documenting intervention fidelity, including regular checks to ensure that the nutritional intervention is being delivered as intended [31]. This may involve collecting detailed records of foods provided to participants, monitoring actual consumption through food diaries or biomarkers, and documenting any deviations from the planned intervention protocol. The CONSORT-Nut guideline emphasizes the importance of transparently reporting these operational details to enable proper interpretation of study findings and facilitate future replication.

Data Analysis and Interpretation Phase

When analyzing and interpreting trial results, researchers should apply the CONSORT-Nut principles to ensure that all relevant aspects of the nutritional intervention are adequately considered in the statistical analysis and results interpretation. This includes carefully accounting for adherence levels in the analysis plan, considering the potential impact of dietary substitutions on observed outcomes, and appropriately contextualizing findings within the broader nutritional landscape.

A key consideration during this phase is the clear distinction between the efficacy of the nutritional intervention itself versus the effectiveness of the implementation strategy [31]. Researchers should also carefully consider whether observed effects might be attributable to the consumption of the food or nutrient of interest, the lack of consumption of the food(s) it replaced, or a combination of both factors [31]. These nuanced interpretations are essential for generating meaningful insights that can inform clinical practice and public health policy.

Manuscript Preparation and Publication Phase

During manuscript preparation, authors should systematically address each item of the CONSORT-Nut checklist, providing clear and complete information about all aspects of the trial methodology and findings. The guideline should be used alongside the standard CONSORT checklist, with particular attention to nutrition-specific items that require enhanced description.

When describing results, authors should ensure that they provide sufficient detail about the intervention composition, participant adherence, and any modifications made during the trial [31]. Additionally, the discussion section should explicitly address the implications of dietary substitutions, cultural adaptations, and real-world applicability of the findings. By adhering to these reporting standards, researchers contribute to the overall improvement of evidence quality in the field of nutritional sciences.

Table 2: Essential Research Reagent Solutions for Nutrition RCTs

Reagent Category	Specific Examples	Function in Nutrition Research	Implementation Considerations
Dietary Assessment Tools	Food frequency questionnaires, 24-hour dietary recalls, food diaries, digital photography	Quantify dietary intake and monitor adherence to nutritional interventions	Select tools with demonstrated validity for target nutrients/foods; standardize administration across study sites
Biomarkers of Nutritional Status	Plasma vitamins, carotenoids, fatty acid profiles, metabolomic panels	Objectively verify nutrient exposure and compliance; provide mechanistic insights	Consider stability, cost, and participant burden when selecting biomarkers; establish standardized collection protocols
Food Composition Databases	USDA FoodData Central, McCance and Widdowson's composition tables, branded food databases	Convert food consumption data to nutrient intake values	Specify database version and any modifications; document handling of missing or imputed values
Dietary Intervention Materials	Standardized food products, portion control tools, recipe manuals, meal plans	Ensure consistent delivery of nutritional intervention across participants	Document specific brands, formulations, and preparation methods; monitor lot-to-lot variability in commercial products
Data Management Systems	Electronic data capture platforms, nutrient analysis software, dietary pattern analysis tools	Manage dietary data, calculate nutrient intake, identify dietary patterns	Ensure systems can handle complex dietary data; document any algorithms used for analysis

Experimental Protocols for Nutrition Trials

Protocol for Standardizing Complex Dietary Interventions

Implementing standardized dietary interventions represents one of the most significant methodological challenges in nutrition research. The following protocol provides a framework for ensuring consistency and reproducibility:

• Intervention Development: Clearly define the nutritional composition of the intervention, including specific foods, nutrients, dietary patterns, or supplements to be tested. Document all components with sufficient detail to enable replication.

• Standardization Procedures: Develop detailed manuals for food preparation, portion control, and delivery methods. For multi-center trials, implement training programs to ensure consistency across sites.

• Quality Control Measures: Establish regular monitoring procedures to verify intervention fidelity, including periodic nutrient analysis of provided foods, documentation of any product formulation changes, and assessment of adherence through appropriate biomarkers when available.

• Documentation Requirements: Maintain comprehensive records of all intervention components, including brand names, lot numbers, preparation methods, and any deviations from the planned protocol.

This systematic approach to intervention standardization helps minimize variability and enhances the validity and interpretability of study findings [31].

Protocol for Adherence Monitoring in Dietary Interventions

Assessing and documenting participant adherence is essential for interpreting the results of nutrition trials:

• Multi-Method Assessment: Implement a combination of adherence measures, which may include self-reported dietary intake (e.g., food records, 24-hour recalls), direct observation, food provision records, and relevant biomarkers.

• Frequency and Timing: Establish a predetermined schedule for adherence assessment that captures representative patterns throughout the intervention period.

• Adherence Criteria: Define explicit criteria for classifying participants as adherent or non-adherent, including specific cut-points for nutrient intake, biomarker levels, or behavioral measures.

• Statistical Handling: Pre-specify how adherence data will be incorporated into the analysis, including plans for per-protocol analyses, dose-response assessments, or other adherence-based models.

This comprehensive approach to adherence monitoring acknowledges the particular challenges in nutrition research and provides a framework for transparent reporting of this critical methodological aspect [31].

Workflow Visualization and Implementation Tools

Diagram 1: CONSORT-Nut Implementation Workflow. This diagram illustrates the three-phase workflow for implementing CONSORT-Nut guidelines throughout the research process, from initial planning through publication. The dashed red lines represent important feedback loops that inform future research and guideline refinement.

Diagram 2: CONSORT-Nut Checklist Application Process. This flowchart details the systematic process for applying CONSORT-Nut guidelines during manuscript preparation, including iterative refinement to address identified reporting gaps.

Impact and Future Directions

The implementation of CONSORT-Nut is expected to have a transformative impact on the field of nutritional sciences by addressing persistent challenges in evidence generation and synthesis. As Dr. Schlüssel notes, "Clinical practice and nutritional guidelines only change when there is high-quality evidence that an intervention works or works better than the current practice. The evidence quality can only be appraised properly if studies are well reported" [31]. By enhancing reporting completeness and transparency, CONSORT-Nut will enable more accurate critical appraisal, more reliable systematic reviews and meta-analyses, and more informed clinical and public health decisions.

The development team anticipates monitoring the uptake and adherence to CONSORT-Nut approximately four to six years after its initial publication, with plans to explore whether updates are needed based on methodological advances or user feedback [31]. Dissemination strategies will include social media engagement, development of a dedicated STAR-NUT website with freely available resources, and partnerships with nutrition societies and associations to promote widespread adoption [31]. Through these coordinated efforts, CONSORT-Nut has the potential to significantly advance the rigor, reproducibility, and clinical relevance of nutrition intervention research, ultimately contributing to improved health outcomes through more evidence-based nutritional practices.

Overcoming Common Challenges in Nutritional Trial Reporting

Accurate dietary assessment is fundamental to nutritional science, yet self-reported intake data are notoriously affected by measurement errors that can seriously compromise the validity of research findings [32]. In the specific context of randomized controlled trials (RCTs), which form the gold standard for establishing causal inference in nutrition, these errors present unique challenges [33]. Measurement error refers to the difference between an individual's true dietary intake and their observed intake, as captured by assessment tools [32]. Within nutritional intervention research, the problem is exacerbated by the potential for differential reporting, where participants in an intervention arm may report their diets differently compared to those in a control group, either due to increased awareness or a desire to appear compliant [34]. Such errors can lead to biased estimates of intervention effects, reduced statistical power, and ultimately, distorted or inconclusive trial results [34] [35]. This Application Note provides detailed protocols and strategies to identify, minimize, and account for measurement error, with the overarching goal of strengthening the evidence base for dietary guidelines and fulfilling the rigorous reporting standards anticipated by CONSORT extensions for nutrition trials [9] [36].

Classifying and Understanding Measurement Error

A critical first step in managing measurement error is to understand its origins and nature. Errors in dietary data are not monolithic; they can be categorized as either random or systematic, each with distinct implications for data analysis and interpretation.

Random error, or within-person variation, affects the precision of dietary measurements. It arises from day-to-day fluctuations in an individual's diet and can be reduced by increasing the number of dietary assessments per person [37] [32]. While random error in an exposure variable typically attenuates observed associations toward the null, making true effects harder to detect, it is generally easier to mitigate than systematic error [35].

Systematic error, or bias, affects the accuracy of the data. It represents a consistent tendency to over- or under-report intake. In intervention studies, a particularly problematic form is differential systematic error, where the direction or magnitude of the error differs between intervention and control groups [34]. For example, participants receiving nutrition counseling may underreport energy intake to a greater extent than the control group, creating a false impression of the intervention's effect [34]. This type of bias is more insidious and cannot be remedied by simply increasing the sample size.

The following table summarizes the common types and sources of error encountered in dietary assessment.

Table 1: Classification and Impact of Measurement Error in Dietary Assessment

Error Type	Description	Common Sources	Primary Impact on Data
Random Error	Day-to-day variation in intake; non-directional imprecision.	Day-to-day dietary variability; quantification mistakes.	Reduces precision; attenuates effect sizes (towards null); lowers statistical power.
Non-Differential Systematic Error	Consistent directional bias across all study groups.	General under-reporting of 'unhealthy' foods; social desirability bias; flawed food composition data.	Reduces accuracy; biases intake estimates at the group level.
Differential Systematic Error	Direction/magnitude of bias differs between study groups.	Intervention group reports with greater/less error due to heightened awareness or desire to appear compliant.	Can create spurious intervention effects or mask true effects; threatens internal validity.

The statistical models describing these relationships are crucial for planning correction methods. The classical measurement error model ((X^* = X + e)) assumes the error (e) is random and independent of the true value (X) [35]. The linear measurement error model ((X^* = \alpha0 + \alphaX X + e)) is more general, accounting for both random error and systematic bias (where (\alpha0) is location bias and (\alphaX) is scale bias) [35]. In intervention studies, the error is often differential, meaning it is related to the outcome or group assignment, making the linear measurement error model particularly relevant [34] [35].

Dietary Assessment Tools and Error Mitigation Protocols

Selecting the most appropriate dietary assessment tool is a strategic decision that must align with the study's objectives, population, and resources. No single method is perfect, and each carries its own error profile. The following section outlines key tools and specific protocols to optimize their implementation and minimize inherent errors.

24-Hour Dietary Recalls

The 24-hour dietary recall is a structured interview designed to capture detailed intake from the previous 24 hours. Its quantitative nature makes it suitable for estimating population-level intakes of foods and nutrients [37]. Modern protocols often use the Automated Multiple-Pass Method (AMPM), developed by the USDA, which employs a standardized five-step pass system to enhance memory retrieval [38].

Detailed Protocol for High-Quality 24-Hour Recalls:

• Training: Interviewers must undergo certified training on the AMPM or an equivalent standardized protocol to minimize interviewer bias.
• Scheduling: Utilizes unannounced recalls (rather than pre-scheduled) to prevent participants from altering their usual diet on the day of reporting [34].
• Administration: The first recall is often conducted in-person, with subsequent recalls performed via telephone. A minimum of two non-consecutive recalls per participant is recommended to estimate and adjust for within-person variation [37] [38].
• Tools: Use of standardized portion-size aids (e.g., graduated food models, photographs, digital interfaces) to improve quantification accuracy [32].
• Quality Control: Implementation of real-time quality control checks during data collection, including range checks for improbable food amounts and prompt review of completed recalls.

Food Frequency Questionnaires (FFQs)

FFQs are designed to capture usual long-term dietary intake by querying the frequency of consumption from a fixed list of foods over a specified period (e.g., the past year). While cost-effective for large epidemiological studies, they are prone to systematic error due to their reliance on memory and cognitive averaging [33].

Detailed Protocol for FFQ Administration and Validation:

• Selection: The FFQ must be population-specific, including foods commonly consumed by the target demographic.
• Calibration: In large cohort studies or trials, calibrate the FFQ against multiple 24-hour recalls or recovery biomarkers in a representative sub-sample to quantify and correct for systematic error [35].
• Analysis: Energy adjustment (e.g., using the nutrient residual model) is often necessary to control for systematic under- or over-reporting linked to total energy intake.

Biomarkers for Objective Validation

Recovery biomarkers provide unbiased, objective measures of intake for specific nutrients and are considered the gold standard for validating self-report data [34] [33].

Key Experimental Protocols for Biomarker Use:

• Doubly Labeled Water (DLW) for Energy Intake: The protocol involves administering a dose of water containing stable isotopes (^2)H and (^{18})O and then collecting urine or saliva samples over a 1-2 week period. The difference in elimination rates between the two isotopes is used to calculate total energy expenditure, which serves as a proxy for energy intake in weight-stable individuals [34].
• 24-Hour Urinary Nitrogen for Protein Intake: Participants collect all urine over a 24-hour period. The total nitrogen content, measured by the Kjeldahl method or chemiluminescence, is used to calculate protein intake (1g urinary nitrogen ≈ 6.25g protein).
• 24-Hour Urinary Sodium/Potassium: Similar to nitrogen, this requires a complete 24-hour urine collection to estimate sodium and potassium intake, crucial for studies on cardiovascular health.

Table 2: Objective Biomarkers for Validating Dietary Intake

Biomarker	Nutrient Assessed	Protocol Summary	Key Considerations
Doubly Labeled Water (DLW)	Total Energy	Administer isotopic dose; collect serial bio-samples (urine/saliva) over 1-2 weeks.	High cost; considered the gold standard for energy expenditure.
24-Hour Urinary Nitrogen	Protein	Collect total 24-hour urine volume; analyze for nitrogen content.	Incomplete collection is a major source of error; requires participant compliance.
24-Hour Urinary Sodium/Potassium	Sodium, Potassium	Collect total 24-hour urine volume; analyze for sodium and potassium.	As above, completeness of collection is critical.
Serum Carotenoids	Fruit & Vegetable Intake	Single fasted blood draw; analysis via High-Performance Liquid Chromatography (HPLC).	Can be confounded by absorption factors and lipid metabolism.

The following workflow diagram illustrates the strategic process for selecting and applying these assessment tools within a nutritional intervention trial.

The Scientist's Toolkit: Research Reagent Solutions

Successful implementation of the protocols above requires a suite of reliable reagents and materials. The following table details essential components of the dietary researcher's toolkit.

Table 3: Research Reagent Solutions for Dietary Assessment and Validation

Tool/Reagent	Function/Application	Specific Examples & Protocols
Standardized Portion Aids	Visual aids to improve accuracy of food amount estimation.	USDA Food Model Booklets, digital photo-atlases, graduated cups/spoons.
Automated Multiple-Pass Method (AMPM)	Software-guided interview protocol to enhance recall completeness.	USDA's AMPM system, integrated into 24-hour recall software platforms.
Doubly Labeled Water Kits	Objective measurement of total energy expenditure.	Pre-measured doses of H₂¹⁸O and ²H₂O; collection vials for urine/saliva.
24-Hour Urine Collection Kits	For biomarker analysis of protein, sodium, and potassium.	Jugs with preservatives (e.g., boric acid), instruction sheets, cold packs.
Food Composition Database (FCDB)	Converts reported foods into nutrient intakes.	USDA Food and Nutrient Database for Dietary Studies (FNDDS), Food Pattern Equivalents Database (FPED).
Social Desirability Scale	Questionnaire to quantify and adjust for reporting bias.	Marlowe-Crowne Social Desirability Scale, included in study questionnaires.

Statistical Analysis and Data Correction Methods

Once data is collected, statistical techniques are required to mitigate the impact of residual measurement error. A foundational concept is the distinction between within-person and between-person variation. The former is treated as random error and is addressed by collecting multiple recalls per person, allowing for the calculation of usual intake distributions [37] [39].

For more sophisticated correction, measurement error models derived from validation studies are used.

• Internal Validation Studies: A sub-sample of the main study population completes both the error-prone dietary tool (e.g., FFQ) and a reference instrument (e.g., multiple 24-hour recalls or a biomarker). The relationship between the two is used to create a calibration equation that is then applied to the entire study cohort [35].
• External Validation Studies: Calibration equations are borrowed from previously published validation studies. This is less ideal than an internal study, as the error structure may not be transportable between populations [35].

The National Cancer Institute (NCI) method is a widely adopted statistical technique for estimating usual intake distributions by separating within-person from between-person variation, often using data from two non-consecutive 24-hour recalls [39].

The following diagram outlines the core logical structure of classifying measurement error, which informs the choice of statistical correction method.

Application within a CONSORT-Nutrition Framework

The move towards a CONSORT extension for nutritional trials underscores the need for transparent and complete reporting of how dietary intake was assessed and how measurement error was addressed [9] [36]. Integrating the strategies outlined in this document into trial design and reporting will significantly enhance the credibility of the evidence generated.

Key reporting items for publication, aligned with this initiative, should include:

• Detailed Dietary Intervention Description: A complete description of the dietary intervention and comparator using a template like TIDieR, including the methods used to deliver the intervention and assess adherence [36].
• Dietary Assessment Method Justification: A rationale for the choice of dietary assessment tool(s), including information on its validity and reliability for the specific nutrients and population under study.
• Protocols to Minimize Bias: Description of specific steps taken to minimize bias, such as using unannounced 24-hour recalls, interviewer training protocols, and methods for handling portion size estimation.
• Validation and Calibration: Reporting on any validation sub-studies conducted, including the reference method used (e.g., biomarker, weighed record) and the resulting calibration equations or correction factors applied.
• Discussion of Limitations: A frank discussion of the potential impact of residual measurement error, particularly differential error, on the study's findings and their interpretation [34].

By explicitly detailing these methodologies, researchers allow for a more critical appraisal of their work and contribute to the cumulative improvement of methodological standards in nutritional science.

Randomized controlled trials (RCTs) represent the gold standard for evaluating interventions in clinical and nutritional research [40]. However, trials investigating nutritional interventions present unique methodological challenges that distinguish them from pharmaceutical trials. Among the most complex are trials comparing food-based interventions with supplement-based approaches, which differ fundamentally in composition, bioavailability, and physiological effects [40] [41]. The CONSORT (Consolidated Standards of Reporting Trials) statement, the established guideline for reporting randomized trials, has recently been updated to the CONSORT 2025 statement to reflect methodological advancements and user feedback [1] [25]. Concurrently, specialized extensions for nutrition trials are under development through initiatives like CONSORT-Nut, recognizing that inadequate reporting of nutrition data can hinder the development of effective nutritional health policies [11] [15]. This article provides application notes and detailed protocols for navigating the reporting complexities specific to food-based versus supplement-based trials within this evolving framework.

Conceptual Framework and Key Distinctions

Defining Food Bioactives and Nutrients

In nutritional science, essential nutrients include vitamins, minerals, and trace elements with established dietary intake recommendations, whose absence leads to deficiency-related diseases. In contrast, food bioactives are defined as "constituents in foods or dietary supplements, other than those needed to meet basic human needs, which are responsible for changes in health status" [40]. These bioactives, such as the flavan-3-ols found in cocoa, are not linked to deficiency diseases but may modulate health risks [40]. This distinction is crucial when designing and reporting trials, as the rationale for testing whole foods versus isolated compounds rests on understanding these conceptual differences.

Comparative Characteristics of Intervention Types

Table 1: Fundamental distinctions between food-based and supplement-based interventions

Characteristic	Food-Based Interventions	Supplement-Based Interventions
Composition	Complex matrix of compounds; whole or minimally processed ingredients [41]	Isolated, purified bioactives or nutrients; often industrial ingredients [41]
Bioactivity	Potential synergistic effects; modified by food matrix	Specific, targeted physiological effects
Generalizability	Directly generalizable to dietary advice [40]	Limited to the specific supplement tested [40]
Control Group	Challenging to define and mask [40]	Facilitates proper blinding with placebo control [40]
Dose-Response	Difficult to establish precise dosages	Clear dose-response patterns can be established [40]

Reporting Standards Framework

CONSORT 2025 Updates

The CONSORT 2025 statement introduces substantial changes from the 2010 version, including seven new checklist items, revision of three items, deletion of one item, and integration of items from key extensions [1] [25]. A significant restructuring includes a new section on open science, encompassing trial registration, protocol accessibility, data sharing, and conflicts of interest [1]. These updates aim to address evolving methodological standards and ensure transparent reporting, which is particularly crucial for nutrition trials where intervention complexity often leads to reporting deficiencies.

Emerging CONSORT-Nut Extension

Initiatives by the Federation of European Nutrition Societies (FENS) and the Supporting Transparency And Reproducibility in studies of NUTritional interventions (STAR-NUT) group are converging toward a consolidated CONSORT-Nut extension [15]. This specialized extension addresses unique aspects of nutrition trials, such as:

• Intervention characterization: Detailed description of food composition, processing methods, and nutrient matrices
• Dietary assessment methods: Specification of tools used to monitor background diet and compliance
• Control diet design: Appropriate matching for energy, macronutrients, and food patterns A Delphi survey to gather feedback on the proposed CONSORT extension for nutrition intervention trials has demonstrated strong expert consensus on necessary reporting items [11].

Application Notes for Food vs. Supplement Trials

Intervention Design and Characterization

Food-based interventions require comprehensive documentation of:

• Food sourcing and processing: Specify suppliers, growing conditions, harvest methods, and post-harvest processing [9]
• Composition analysis: Report macronutrient, micronutrient, and bioactive composition using standardized methods
• Stability testing: Document nutrient retention throughout study duration
• Preparation instructions: Standardize cooking methods and serving sizes

Supplement-based interventions necessitate detailed reporting of:

• Manufacturing specifications: Include manufacturer, quality control procedures, and certificate of analysis
• Excipient documentation: List all non-active ingredients that may affect bioavailability
• Bioavailability verification: Report testing for dissolution and absorption characteristics
• Stability data: Provide evidence of compound stability over the study period

Control Group Design Considerations

A key challenge in food-based trials is selecting an appropriate control that eliminates expectancy effects. Strategies include:

• Placebo foods: Designing control foods that mimic active foods in appearance, taste, and texture without containing the bioactive of interest
• Factorial designs: Employing 2x2 factorial designs that test both food and supplement forms, as exemplified by the COcoa Supplement and Multivitamin Outcomes Study (COSMOS) [40]
• Wait-list controls: Implementing control groups that receive the intervention after the active treatment period

Adherence Assessment Protocols

For food-based interventions:

• Implement daily food checklists with portion size images
• Conduct periodic 24-hour dietary recalls
• Utilize biometric markers (e.g., plasma carotenoids for fruit/vegetable interventions)
• Apply photographic food records when feasible

For supplement-based interventions:

• Conduct pill counts at regular intervals
• Use electronic monitoring systems (e.g., MEMS caps)
• Measure biological compliance markers specific to the supplement

Table 2: Outcome assessment considerations for food versus supplement trials

Outcome Domain	Food-Based Trials	Supplement-Based Trials
Primary Outcomes	Often hard clinical endpoints (e.g., CVD events) [40]	Frequently intermediate endpoints (e.g., blood pressure, lipids) [40]
Microbiome Analysis	Essential for whole food interventions [41]	Less emphasized unless specifically relevant
Systemic Effects	Broad profiling of multiple health parameters	Targeted mechanism-based outcomes
Adverse Events	Typically food intolerance or acceptability issues	Specific supplement-related side effects

Experimental Protocols

Protocol for Randomized Controlled Feeding Trial

The following protocol outlines a methodology for comparing food-based versus supplement-based interventions, adapted from a study investigating very-low-energy diets [41]:

Study Design:

• Single-blind, two-arm, parallel-group, randomized controlled trial
• Duration: 3 weeks active intervention with follow-up assessments
• Participants: 47 women (30-65 years) with BMI 30-45 kg/m²

Randomization and Blinding:

• Computer-generated block randomization sequence
• Participants blinded to group assignment and study hypotheses
• Research staff conducting assessments blinded to group assignment

Intervention Arms:

• Food-based arm: Pre-packaged meals comprising approximately 93% whole-food ingredients, providing 800-900 kcal/day
• Supplement-based arm: Shakes, soups, bars, and desserts comprising approximately 70% industrial ingredients, providing 800-900 kcal/day

Primary Outcome:

• Species-level alpha diversity of gut microbiome (Shannon index)

Secondary Outcomes:

• Species richness, beta diversity, and taxonomic composition
• Anthropometrics (weight, BMI, waist circumference)
• Serum biomarkers (lipids, glucose, inflammatory markers)
• Mental health, sleep quality, and gastrointestinal symptoms

Statistical Analysis:

• Modified intention-to-treat (mITT) approach
• Diet group × time interactions assessed as beta coefficients (β) with 95% confidence intervals

Diagram 1: RCT protocol for food vs. supplement trial

Protocol for Large-Scale Long-Term Outcome Trial

For long-term trials examining clinical endpoints such as cardiovascular disease or cancer, the following protocol elements are essential, drawing from successful trials like VITAL and COSMOS [40]:

Study Design:

• 2×2 factorial, randomized, double-blind, placebo-controlled design
• Duration: 5+ years to capture sufficient clinical endpoint data
• Multicenter recruitment to achieve sample sizes >20,000 participants

Participant Population:

• Target population defined by age and risk factors (e.g., women ≥65 years and men ≥60 years for COSMOS)
• Exclusion criteria: conditions that might limit adherence or follow-up, contraindications to interventions

Intervention Specifications:

• Active intervention: Well-characterized food extract or whole food product with documented bioactive content
• Placebo control: Matched for appearance, taste, and packaging without active components
• Dosage: Based on previous pilot studies establishing safety and efficacy

Endpoint Adjudication:

• Primary endpoints: Major clinical events (e.g., myocardial infarction, stroke, cancer incidence)
• Secondary endpoints: Intermediate biomarkers, disease-specific mortality, safety parameters
• Independent endpoint adjudication committee blinded to treatment assignment

The Scientist's Toolkit

Research Reagent Solutions

Table 3: Essential research reagents and materials for food and supplement trials

Reagent/Material	Function/Application	Specification Requirements
Standardized Food Extracts	Provide consistent bioactive doses in supplement trials	Certificate of analysis for key bioactives; stability data
Placebo Matching Materials	Create indistinguishable control products	Matching color, texture, taste; inert fillers
Dietary Assessment Software	Quantify background diet and compliance	Multiple-pass 24-hour recall capability; nutrient database
Biological Sample Collection Kits	Standardize pre-analytical procedures	EDTA tubes for plasma; stabilizers for microbiome samples
Compliance Monitoring Tools	Objectively measure intervention adherence	Electronic pill caps; photographic food records
Biomarker Assay Kits	Quantify target engagement and efficacy	Validated for specific matrix (serum, plasma, urine)
Microbiome Analysis Reagents	Assess gut microbiota composition	DNA extraction kits; 16S rRNA or shotgun sequencing primers

Data Collection and Management Infrastructure

Diagram 2: Data management workflow

Navigating the complexities of reporting for food-based versus supplement-based trials requires meticulous attention to intervention characterization, appropriate control groups, and comprehensive outcome assessment. The evolving CONSORT framework, including the general CONSORT 2025 statement and the emerging CONSORT-Nut extension, provides essential guidance for achieving transparent, reproducible reporting. By implementing the protocols and application notes outlined in this article, researchers can enhance the methodological rigor and reporting quality of nutritional intervention trials, ultimately strengthening the evidence base for dietary recommendations and public health policy.

Within the framework of developing CONSORT extensions for nutritional intervention trials, the precise documentation of co-interventions—specifically dietary replacements and background diets—represents a critical methodological challenge. Unlike pharmaceutical trials, nutrition research must account for complex dietary contexts that can significantly modulate intervention effects. Incomplete reporting of these elements compromises the internal validity of trials and hinders their replication and translation into evidence-based practice. This document provides application notes and experimental protocols to standardize the handling and reporting of dietary co-interventions, aligning with ongoing international efforts to create the CONSORT-Nutrition (CONSORT-Nut) extension [15] [9].

Application Notes: Core Principles for Dietary Co-interventions

Defining Dietary Co-interventions

In nutritional trials, a co-intervention is any dietary component or practice, outside the primary experimental intervention, that can influence the study outcomes. Their systematic documentation is essential for isolating the effect of the intervention of interest.

• Dietary Replacements: The specific food, meal, or nutrient that is being substituted or modified by the intervention (e.g., a meal replacement shake replacing a usual breakfast).
• Background Diet: The participant's habitual dietary intake throughout the trial period, which forms the metabolic context for the intervention.

Consequences of Inadequate Reporting

Failure to adequately document and report these elements introduces significant bias and limits the utility of research:

• Reduced Internal Validity: Unmeasured differences in background diets can be a major source of confounding, making it impossible to attribute outcomes solely to the intervention [9].
• Impaired Replicability: Without precise details of the dietary replacement and the dietary context, other researchers cannot faithfully reproduce the intervention [28].
• Ambiguous Interpretation: Inconsistent reporting of compliance, dietary substitutions, and background intake obscures the true dose-response relationship and complicates the interpretation of null or adverse findings [42] [15].

Selecting an appropriate tool for assessing background diet and compliance is paramount. The choice depends on the research question, study design, sample size, and the specific nutrients or foods of interest. The following table summarizes the key characteristics of common dietary assessment methods.

Table 1: Comparison of Primary Dietary Assessment Methods for Use in Clinical Trials

Method	Primary Scope & Time Frame	Key Strengths	Key Limitations	Best Suited for Measuring
Food Record / Diary [29]	Total diet; Short-term (current intake)	High detail for specific days; Does not rely on memory	High participant burden; Reactivity (participants may change diet); Requires literate/motivated population	Detailed background diet during critical intervention periods; Actual intake of specific nutrients.
24-Hour Recall (24HR) [29]	Total diet; Short-term (past 24 hours)	Low participant burden per recall; Does not alter intake; Useful for diverse populations	Relies on memory; Single recall not representative of usual intake; Requires multiple recalls to estimate habitual diet	Habitual background diet (when multiple, non-consecutive recalls are collected); Population-level average intake.
Food Frequency Questionnaire (FFQ) [29]	Total diet or specific components; Long-term (habitual intake over months/year)	Captures habitual diet; Cost-effective for large samples; Ranks individuals by intake	Less precise for absolute intake; Limited by fixed food list; Can be confusing for participants	Long-term patterns in background diet; Intake of specific food groups or nutrients over time.
Dietary Screener [29]	A few specific components (e.g., fruits, fats); Short or long-term	Rapid administration; Low burden; Cost-effective	Narrow focus only; Must be validated for the target population	Compliance with specific dietary targets (e.g., fruit/vegetable servings); Rapid checks on key intervention components.

Experimental Protocols

Protocol for Documenting Dietary Replacements

Objective: To fully characterize the composition, administration, and substitution of the dietary intervention to ensure safety, replicability, and accurate interpretation.

Table 2: Essential Data to Collect for a Dietary Replacement Intervention

Data Category	Specific Items to Document	Rationale
Intervention Composition	Full nutrient profile (macronutrients, micronutrients, energy density), source of ingredients, batch details, physical form.	Allows for replication and safety assessment; essential for evaluating dose-response [9].
Administration	Precise timing, frequency, duration of provision, instructions given to participants (e.g., with/without meals).	Ensures consistent delivery and helps identify temporal effects on outcomes.
What is Replaced	The specific meal, food item, or nutrient being substituted. The nutritional composition of the replaced item, if known.	Critical for calculating the net change in dietary intake and understanding the intervention's metabolic effect [42].
Compliance Assessment	Method for measuring adherence (e.g., returned product count, biochemical biomarkers, participant diaries). Definition of a "compliant" participant.	Quantifies actual exposure to the intervention, vital for per-protocol analysis and interpreting trial results [28].

Protocol for Assessing Background Diet

Objective: To quantify the habitual dietary intake of participants throughout the trial period to identify potential confounding and effect modification.

• Tool Selection: Choose the most appropriate method from Table 1 based on your trial design. For example, use multiple 24HRs in a large efficacy trial or weighed food records in a small, highly controlled feeding study [29].
• Baseline Assessment: Conduct a comprehensive assessment before randomization to establish baseline equivalence between study arms and for use as a covariate in analyses.
• Ongoing Monitoring: Implement periodic assessments during the trial (e.g., every 3-6 months) to capture seasonal variations and changes in habitual intake over time.
• Timing and Frequency: Schedule assessments on both weekdays and weekends to account for intra-individual variation. The number of days depends on the nutrient of interest; more variable nutrients require more days of assessment [29].
• Data Management and Analysis:
  • Utilize standardized nutrient databases for analysis.
  • For 24HRs and food records, employ statistical methods (e.g., the National Cancer Institute method) to estimate usual (long-term) intake from short-term measurements [29].
  • Pre-define how background diet data will be used in statistical models (e.g., as a covariate, for subgroup analysis).

Visualization of Workflows

Dietary Co-intervention Management Workflow

The following diagram outlines the logical sequence for handling dietary co-interventions throughout a trial's lifecycle, from planning to analysis.

Dietary Assessment Selection Logic

This decision tree guides researchers in selecting the most appropriate dietary assessment method based on study-specific constraints and objectives.

The Scientist's Toolkit: Research Reagent Solutions

Table 3: Essential Materials and Tools for Dietary Co-intervention Research

Tool / Material	Function in Dietary Co-intervention Research
Automated Self-Administered 24HR (ASA24) [29]	A freely available, web-based tool for collecting multiple 24-hour recalls automatically, reducing interviewer burden and cost.
Validated Food Frequency Questionnaire (FFQ)	A population-specific questionnaire to estimate habitual intake of nutrients and foods over a long period, critical for characterizing background diet.
Standardized Nutrient Database	A comprehensive database used to convert reported food consumption into nutrient intake values, essential for all assessment methods.
Dietary Compliance Biomarkers	Objective measures (e.g., plasma fatty acids for fish intake, urinary nitrogen for protein) to validate self-reported data and assess adherence [29].
Electronic Food Scale	Provides precise measurement of food portions for weighed food records, increasing the accuracy of intake data in highly controlled studies.
CONSORT-Nut Checklist (Proposed) [15] [9]	A reporting guideline under development to ensure transparent and complete reporting of nutritional interventions, including co-interventions.

The need for optimized adherence reporting is a central focus in the ongoing development of a CONSORT (Consolidated Standards of Reporting Trials) extension for nutrition trials. Randomized controlled trials (RCTs) in nutrition are inherently more complex than pharmaceutical trials. This complexity arises from the influence of background diet and nutritional status, which are difficult to control or measure, and the frequent challenge of effectively blinding interventions, especially whole foods or dietary behavior studies [10]. Incomplete reporting of adherence and methodological details complicates risk-of-bias assessments, often leading to a lower GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) of evidence when results are synthesized in systematic reviews and meta-analyses [10]. Therefore, precise adherence reporting is not merely a procedural detail but a fundamental requirement for enhancing the credibility and utility of nutrition research, enabling its translation into sound public health policy and food innovation [10].

Core Concepts and Definitions of Adherence

In the context of dietary studies, adherence refers to the degree to which participants follow the prescribed nutritional intervention, including both objective measures (e.g., attendance, biomarker analysis) and self-reported measures (e.g., food intake records) [43]. A lack of robust adherence measurement can lead to the erroneous conclusion that an intervention is ineffective when, in fact, null effects may be explained by low participant compliance [43]. The emerging CONSORT-nutrition (CONSORT-nut) guidelines aim to address these reporting gaps by providing detailed, discipline-specific extensions to the standard CONSORT checklist, ensuring that all nuances of nutrition trials are adequately captured [44] [10].

Quantitative Data Presentation on Adherence and Outcomes

The relationship between adherence levels and key study outcomes must be clearly quantified. The table below summarizes findings from a retrospective analysis of the Nutrition and Exercise Lifestyle Intervention Program (NELIP), which utilized a dedicated adherence measurement tool [43].

Table 1: Adherence Scores and Gestational Weight Gain Outcomes by Pre-pregnancy BMI Category

Pre-pregnancy BMI Category	Adherence Score (Mean) - Acceptable Weight Gain	Adherence Score (Mean) - Excessive Weight Gain	Statistical Significance (p-value)
Normal Weight	Reported higher adherence	Reported lower adherence	< 0.05
Overweight	Reported higher adherence	Reported lower adherence	< 0.05
Obese	Reported higher adherence	Reported lower adherence	< 0.05

The data demonstrates that irrespective of pre-pregnancy BMI, participants who gained weight within acceptable limits had significantly higher adherence scores than those with excessive weight gain [43]. This underscores that adherence is a critical modifier of intervention effectiveness across all participant types.

Experimental Protocols for Measuring Adherence

Protocol 1: Designing a Composite Adherence Measurement Tool

This protocol is based on the tool developed for the NELIP study, which combined both objective and self-reported measures into a single composite score [43].

• Step 1: Identify Intervention Goals. Define the specific, measurable nutrition and exercise goals of the intervention. For NELIP, this included three nutrition goals (e.g., maintaining a specific daily energy intake) and exercise goals [43].
• Step 2: Define Measurable Parameters. For each goal, establish the parameters to be tracked.
• Step 3: Assign a Grading System. Create a system to grade adherence to each parameter. This can be a percentage of goals met or a points-based system.
• Step 4: Combine Scores. Aggregate the individual scores for each parameter to create a total composite adherence score for each participant.
• Step 5: Validate Against Outcome. Correlate the composite adherence scores with the primary study outcome (e.g., gestational weight gain) to validate the tool's predictive value, as shown in Table 1 [43].

Protocol 2: Reporting Adherence per CONSORT-Nutrition Guidelines

This protocol outlines the specific adherence-related information that should be reported in publications, as guided by the draft CONSORT-nutrition checklist [44].

• Intervention Details (Checklist Item 5): Report "acceptability and tolerance of intervention" [44]. Describe the dietary intervention and comparator with sufficient detail to allow replication, including form, matrix, preparation, and stability. For behavioral interventions, describe the protocol, who administered it, and when [44].
• Assessment of Background Diet (Checklist Item 5): Include a "description of assessment of background diets as relevant" [44]. This is crucial for contextualizing adherence.
• Statistical Methods (Checklist Item 12a): Describe the "per-protocol compliance cutoffs" and "possible exclusion criteria for misreporting" [44]. The analysis plan should include both intention-to-treat and per-protocol analyses, with comparisons between them [44].

Visual Workflow for Adherence Measurement and Reporting

The following diagram illustrates the integrated workflow for measuring adherence in a dietary study and integrating its reporting into the CONSORT-nut framework.

The Scientist's Toolkit: Research Reagent Solutions

The following table details key tools and materials essential for effectively measuring and reporting adherence in dietary intervention studies.

Table 2: Essential Research Reagents and Tools for Adherence Measurement

Item/Tool	Primary Function in Adherence Measurement
Composite Adherence Tool [43]	A structured grading system to combine multiple objective and self-reported adherence measures into a single, quantifiable score for analysis.
24-Hour Food Intake Records [43]	Self-reported tool for participants to log daily food and beverage consumption, allowing researchers to assess adherence to dietary prescriptions.
Biomarker Assay Kits	Objective biochemical analysis of biological samples (e.g., blood, urine) to verify intake of specific nutrients or food components.
CONSORT-Nutrition Checklist [44] [10]	Reporting guideline extension ensuring complete and transparent reporting of all adherence-related methodological details in trial publications.
Electronic Data Capture (EDC) System	Digital platform for secure, efficient, and accurate collection and management of real-time adherence data from participants.

Validating CONSORT-Nut: Comparative Analysis with Other Extensions

Randomized Controlled Trials (RCTs) represent the gold standard for evaluating healthcare interventions, yet nutrition trials present unique methodological challenges that distinguish them from pharmaceutical studies. The CONSORT-Nut initiative addresses a critical gap in research methodology by developing an evidence-based extension of the Consolidated Standards of Reporting Trials (CONSORT) statement specifically tailored to nutritional interventions [31]. This development responds to the recognized problem that incomplete reporting and lack of transparency are particularly problematic in nutrition research, where complex interventions involving foods, diets, and nutritional supplements present reporting challenges not adequately covered by existing guidelines [15] [19].

Nutritional trials differ fundamentally from pharmaceutical trials in several key aspects: the influence of background diet and nutritional status is nearly impossible to fully control, blinding is often difficult or impossible particularly for whole foods/diet interventions, and available comparators frequently fail to provide true placebos [10]. Furthermore, when participants consume a specific food or diet, they are necessarily not consuming other foods, creating complex substitution effects that are challenging to measure and account for [31]. These methodological particularities have created an urgent need for reporting standards specific to nutrition science, prompting the development of CONSORT-Nut through a rigorous, empirically-driven process.

The Empirical Foundation of CONSORT-Nut

Systematic Evidence Gathering Through Literature Reviews

The CONSORT-Nut development process began with comprehensive systematic examinations of the current state of nutrition trial reporting. The Supporting Transparency And Reproducibility in studies of NUTritional interventions (STAR-NUT) working group, hosted within the Enhancing the QUAlity and Transparency Of health Research (EQUATOR) network, designed a research program following established EQUATOR methodology to support transparency across the nutrition intervention research pipeline [15] [19]. This initiative conducted systematic literature reviews to identify and characterize the main reporting limitations in nutritional interventions, with these comprehensive reviews now complete and submitted for publication [19].

Concurrently, the Federation of European Nutrition Societies (FENS) "Improving Standards in the Science of Nutrition" initiative worked to evaluate and identify key elements of human nutrition intervention trials that should be reported in a standardized way [15] [10]. This dual approach ensured that the guideline development was informed by both systematic review of published literature and practical experience from active researchers in the field. The empirical data gathered through these reviews identified critical reporting gaps in nutrition trials, particularly concerning poorly defined outcomes, insufficient methodological detail, and inadequate description of interventions and comparators [10].

Stakeholder Engagement and Consensus Building

The CONSORT-Nut development process has incorporated extensive stakeholder engagement to ensure practical applicability and wide acceptance. An international group of academics from 14 institutions across 12 countries and 5 continents, working under the FENS initiative, reviewed the existing CONSORT statement checklist as it pertains to nutrition trials [9] [45]. This perspective piece documented the procedure for gaining input and consensus on a preliminary checklist, including presentation and interrogation at the International Union of Nutritional Sciences International Congress of Nutrition 2022, inputs from a survey of journal editors, and pilot testing on eight nutrition trials of diverse designs [45].

The development process further employed a Delphi survey to gather structured feedback from the nutrition research community on the proposed extension items [15]. This systematic approach to consensus building allowed for the incorporation of diverse viewpoints while maintaining methodological rigor. The initiative has been met with considerable enthusiasm from the scientific community, with journal editors particularly expressing support for standardized nutrition reporting guidelines [9] [45].

Table 1: Key Empirical Studies Informing CONSORT-Nut Development

Study Component	Methodology	Key Findings	Status
Systematic Literature Reviews [15] [19]	Comprehensive review of diet- and nutrition-related RCTs	Identified main reporting limitations in nutritional interventions	Completed and submitted for publication
Stakeholder Delphi Survey [15]	International online survey gathering feedback on proposed checklist items	Gathering community input on extension proposals	Underway as of 2024 publications
Pilot Testing [45]	Application of proposed checklist to 8 diverse nutrition trials	Provided evidence that reporting of nutrition trials can be improved	Completed
Journal Editor Survey [9] [45]	Solicited feedback from editors of nutrition journals	Strong enthusiasm for nutrition-specific reporting guidelines	Completed

Methodological Framework and Development Protocol

Structured Development Approach

The CONSORT-Nut extension follows a rigorously structured development protocol aligned with EQUATOR Network recommendations for reporting guideline development. The process began with the registration of the STAR-NUT research programme within the EQUATOR Network, officially titled "Securing Transparency And Reproducibility in studies of NUTritional interventions" [15] [19]. This program aims to deliver evidence-based developments for three reporting guidelines that cover the complete nutrition intervention research pipeline: SPIRIT for trial protocols, CONSORT for randomized controlled trials, and PRISMA for meta-analyses of nutrition studies [19].

The methodological framework for CONSORT-Nut development follows a multi-stage process that includes: (1) identification of nutritional intervention types studied over the past decade through systematic literature screening; (2) critical appraisal of reporting completeness in publications describing these studies; (3) compilation of evidence from literature reviews; (4) stakeholder surveys to gather opinions on findings; (5) pilot testing of recommendations with nutrition researchers; and (6) finalization of recommendations accompanied by real-study examples of good reporting [31]. This structured approach ensures that the resulting guideline is both evidence-based and practical for implementation.

Integration with Updated CONSORT Standards

A critical aspect of the CONSORT-Nut development is its alignment with the recently released CONSORT 2025 statement, which represents a substantial update to the previous 2010 version [7] [46]. The CONSORT 2025 statement introduced significant changes, including seven new checklist items, three revised items, one deleted item, and integration of several items from key CONSORT extensions, along with a restructured checklist featuring a new section on open science [46]. These updates account for recent methodological advancements and incorporate feedback from end users through a comprehensive process including a scoping review of literature, development of an evidence database, and an international three-round Delphi survey involving 317 participants [46].

CONSORT-Nut builds upon this updated framework, ensuring that the nutrition-specific extension incorporates the most current standards for trial reporting while addressing the unique aspects of nutritional interventions. The development team has secured funding for a consensus meeting that will discuss the format and items to be included in the nutrition extension, with the goal of finalizing the CONSORT-Nut checklist and providing worked examples of good reporting [15] [19].

Diagram 1: CONSORT-Nut Development Workflow. This diagram illustrates the evidence-based development process for CONSORT-Nut, highlighting the integration of empirical research throughout the workflow.

Key Reporting Challenges in Nutrition Trials

Methodological Complexities of Nutritional Interventions

Nutritional interventions present unique methodological challenges that necessitate specialized reporting standards. Unlike pharmaceutical trials where interventions typically involve a single compound, nutritional interventions are often complex, multi-component, and difficult to standardize [10] [31]. As highlighted by researchers involved in CONSORT-Nut development, "when you eat rice, you usually use it to replace potatoes, or pasta, or bread, or any other kind of food alike in the meal you prepared" [31]. This substitution effect creates significant challenges for attributing observed outcomes specifically to the intervention rather than to the concomitant reduction or elimination of other dietary components.

The background diet and nutritional status of participants introduces another layer of complexity, as these factors are nearly impossible to fully control yet may significantly influence intervention outcomes [10]. Additionally, the physiological timeframe of nutritional interventions requires careful consideration, as the length of intervention must be justified with respect to the physiological processes being influenced [10]. These methodological particularities distinguish nutrition trials from pharmaceutical trials and create specific reporting requirements that are not adequately addressed by existing CONSORT guidelines.

Specific Reporting Gaps in Nutrition Literature

Research conducted by both the FENS and STAR-NUT groups has identified consistent reporting gaps in the nutrition trial literature. These include inadequate description of intervention components, insufficient detail about comparator treatments, poorly defined outcomes with unclear relevance to nutritional status, and incomplete reporting of adherence measures [10] [31]. The lack of methodological detail in many nutrition trial reports makes risk of bias assessments challenging, leading to an overall lower GRADE of evidence when results are combined in systematic reviews and meta-analyses [10].

Current reporting limitations also affect the ability to translate research findings into practice and policy. As noted by developers of the CONSORT-Nut initiative, "Clinical practice and nutritional guidelines only change when there is high-quality evidence that an intervention works or works better than the current practice. The evidence quality can only be appraised properly, if studies are well reported" [31]. The gaps in nutrition trial reporting thus have implications not only for research synthesis but also for public health nutrition guidance and food product innovation.

Table 2: Key Methodological Challenges in Nutrition RCTs and CONSORT-Nut Solutions

Challenge Category	Specific Challenges	CONSORT-Nut Addressing Strategy
Intervention Complexity	Multi-component interventions, substitution effects, difficulty with blinding	Tailored reporting standards for different intervention types (supplements, whole foods, dietary patterns)
Contextual Factors	Background diet, nutritional status, cultural/religious food practices	Guidance on reporting and accounting for contextual influences
Measurement Issues	Dietary assessment measurement error, biomarker variability	Standards for reporting measurement methods and their limitations
Comparator Selection	Lack of appropriate placebos for food-based interventions	Guidance on comparator description and justification
Implementation Factors	Adherence measurement, intervention fidelity, contamination	Standards for reporting implementation quality and adherence

Implementation and Future Directions

Planned Implementation Strategy

The CONSORT-Nut development team has outlined a comprehensive implementation strategy to ensure widespread adoption across the nutrition research community. Following the finalization of the extension, the working group plans to produce online freely available tools that can be used by research supervisors and lecturers throughout the nutrition higher education system to promote use of the extension throughout the trial process [10]. Additional implementation activities will include webinars, conference sessions, and collaboration with journal editors to promote adoption [10].

The implementation plan also includes social media dissemination through dedicated channels (@consort_nut) to engage with nutrition researchers and other stakeholders [31] [19]. The STAR-NUT initiative will develop a dedicated website where all publications and associated resources will be freely available for download, including checklists, pools of good reporting examples, and reporting quality evaluation tools [31]. The developers emphasize that "CONSORT-NUT will not eliminate the methodological challenges of nutritional intervention studies but pave the way to address them" [31] by increasing transparency and completeness in reporting.

Monitoring Impact and Planned Updates

The CONSORT-Nut initiative includes plans for ongoing evaluation and refinement following initial publication. As stated by the development team, "Part of our research programme is to monitor the uptake and adherence to CONSORT-NUT, as well as explore whether updates are needed, either due to methodological advances in the field, or based on user's feedback" [31]. The team anticipates beginning to explore adoption and impact approximately four to six years after the initial publication, at which point they will assess the need for updates or changes in dissemination strategies.

The target timeline for finalization and journal implementation of CONSORT-Nut is 2026 [10]. The developers note that editors of nutrition journals have expressed enthusiasm about this development, suggesting strong potential for widespread adoption once the extension is finalized [10]. The implementation of CONSORT-Nut is expected to improve the inclusivity of nutrition RCTs in systematic reviews, enhance risk of bias rating, increase the potential for inclusion in meta-analyses, and ultimately strengthen confidence in translating findings into public health policy and food product innovation [10].

Essential Research Reagents and Methodological Tools

Table 3: Key Research Reagents and Methodological Tools for Nutrition Trial Reporting

Tool Category	Specific Examples	Application in CONSORT-Nut Development
Reporting Guideline Frameworks	EQUATOR Network methodology, CONSORT 2025 statement	Foundation for developing nutrition-specific extension using established methodology
Consensus Building Tools	Delphi survey methodology, World Café discussion format, Stakeholder engagement platforms	Structured approaches to gather and incorporate feedback from international nutrition research community
Evidence Synthesis Methods	Systematic literature review protocols, Meta-research methodologies	Comprehensive assessment of current reporting quality and identification of specific gaps
Reporting Quality Assessment Instruments	Adherence checklists, Reporting quality evaluation tools	Tools to assess implementation and impact of CONSORT-Nut following publication
Dissemination Platforms	Dedicated websites, Social media channels, Scientific society partnerships	Mechanisms for widespread distribution and implementation of the final guideline

The development of CONSORT-Nut represents a rigorous, evidence-based approach to addressing the unique methodological challenges inherent in nutrition randomized controlled trials. Through systematic literature reviews, stakeholder engagement, consensus building, and pilot testing, the initiative is building a comprehensive reporting framework specifically tailored to nutritional interventions. By accounting for complexities such as background diet influences, substitution effects, intervention standardization challenges, and appropriate outcome measurement, CONSORT-Nut will fill a critical gap in nutrition research methodology.

The empirical foundation of CONSORT-Nut ensures that the resulting guideline will be both methodologically sound and practically applicable across the diverse spectrum of nutrition research. Implementation of CONSORT-Nut, anticipated in 2026, is expected to significantly enhance the transparency, completeness, and overall quality of nutrition trial reporting, ultimately strengthening the evidence base for dietary guidance, public health policy, and clinical practice recommendations.

The CONSORT (Consolidated Standards of Reporting Trials) statement provides an evidence-based minimum set of recommendations for reporting randomized trials, aimed at facilitating complete and transparent reporting [47]. The core CONSORT guideline has undergone periodic updates, with the CONSORT 2025 statement comprising a 30-item checklist and a participant flow diagram [47] [8]. This foundational framework ensures that trial reports contain sufficient detail to allow for critical appraisal and interpretation. However, certain trial aspects or designs require more specialized reporting guidance, leading to the development of CONSORT extensions that elaborate on specific methodological considerations without replacing the core checklist [48].

Within this ecosystem of reporting guidelines, CONSORT-ROUTINE and CONSORT-PRO serve distinct but complementary functions. CONSORT-ROUTINE addresses trials conducted using cohorts and routinely collected data, while CONSORT-PRO provides specific guidance for trials that incorporate patient-reported outcomes. For nutritional intervention trials, both extensions offer valuable methodological guidance that can enhance reporting quality, though neither is nutrition-specific. Understanding the relationship between these extensions and their application to nutrition research provides a foundation for developing more targeted reporting standards for the field.

Comparative Analysis of CONSORT-ROUTINE and CONSORT-PRO

Table 1: Direct Comparison of CONSORT-ROUTINE and CONSORT-PRO Extensions

Aspect	CONSORT-ROUTINE	CONSORT-PRO
Primary Focus	Trials using cohorts/routinely collected data (registries, electronic health records, administrative databases) [48]	Trials with patient-reported outcomes (PROs) as primary or key secondary endpoints [49]
Core Application	Embedded, nested, or registry-based trials that use existing data sources for identification, recruitment, intervention delivery, or outcome assessment [48]	Trials measuring outcomes directly from patients without clinician interpretation (health-related quality of life, symptoms, satisfaction, adherence) [49]
Key Modifications	8 modified CONSORT items + 5 new items [48]	5 PRO-specific extension items + 9 PRO-specific elaborations to CONSORT 2010 items [50]
Data Source Considerations	Emphasizes data quality, linkage, and handling of routinely collected data; describes database representativeness [48]	Focuses on PRO instrument validity, reliability, and appropriateness for population; mode and timing of administration [49]
Methodological Emphasis	Database integration, consent models for integrated data systems, representativeness of participants from source population [48]	PRO-specific hypothesis, missing data handling, clinical interpretability of results, avoidance of selective reporting [49] [50]

Integration with Core CONSORT Principles

Both extensions function as modular enhancements to the core CONSORT checklist rather than standalone guidelines. When applying either extension, authors must still complete all relevant items from the standard CONSORT checklist, with the extension items providing additional specificity for particular methodological considerations. The CONSORT 2025 update has restructured the checklist with a new section on open science, including items on trial registration, protocol accessibility, data sharing, and conflicts of interest [47], which provide a foundation for both specialized extensions.

The development methodologies for both extensions followed established EQUATOR Network guidelines, employing Delphi surveys with international stakeholders, consensus meetings, and pilot testing [48] [49]. This rigorous development process ensures that both guidelines address the most critical reporting gaps for their respective methodological focuses.

Application to Nutritional Intervention Trials

Relevance of CONSORT-ROUTINE to Nutrition Research

Nutritional intervention trials increasingly leverage routinely collected data from electronic health records, dietary registries, and administrative databases to enhance efficiency and real-world relevance. CONSORT-ROUTINE provides essential guidance for reporting these methodological approaches, which present unique considerations for nutrition research:

• Database Selection and Integration: Nutrition trials using routine data must report on the source and quality of dietary intake data, nutritional status indicators, and food purchasing records, describing how these data elements were validated for research use [48].
• Representativeness and Generalizability: As nutrition trials often aim to inform public health guidelines, reporting on how participants from routine data sources represent the target population is crucial for applying findings to practice [48].
• Hybrid Design Considerations: Many nutrition trials combine prospective data collection with routine data, requiring clear reporting of which elements used routine data and which were trial-specific [48].

Relevance of CONSORT-PRO to Nutrition Research

Patient-reported outcomes are particularly valuable in nutrition research where many outcomes of interest (e.g., dietary satisfaction, gastrointestinal symptoms, quality of life) are best captured directly from participants. CONSORT-PRO addresses key reporting elements for these trials:

• PRO Instrument Selection: Nutrition trials must report the rationale for selecting specific PRO measures and evidence of their validity in the study population, particularly when assessing subjective experiences like hunger, cravings, or food preferences [49].
• Missing Data Management: PRO data in nutrition trials often face unique challenges with missing data due to the burden of repeated dietary assessments or symptom diaries, requiring transparent reporting of handling methods [50].
• Clinical Interpretation: Nutrition trial reports should facilitate interpretation of PRO results by providing context for clinically important differences in scores and relating these to other trial outcomes [49].

Complementary Application in Nutrition Research

Many contemporary nutrition trials can benefit from applying aspects of both extensions simultaneously. For example, a trial using electronic health records to identify participants with specific nutritional needs (CONSORT-ROUTINE elements) while collecting PROs on dietary satisfaction and symptoms (CONSORT-PRO elements) would need to implement guidance from both extensions.

Table 2: Simultaneous Application of CONSORT-ROUTINE and CONSORT-PRO in Nutrition Trials

Trial Scenario	CONSORT-ROUTINE Application	CONSORT-PRO Application
Registry-based trial of medical nutrition therapy	Report how nutritional status data from registry was used for eligibility assessment and outcome measurement [48]	Describe PRO instruments used to assess nutrition impact symptoms and their validity in study population [49]
Pragmatic trial using EHR data for recruitment	Detail how electronic health records identified patients with specific dietary patterns or nutritional risk factors [48]	Report handling of missing PRO data from dietary satisfaction questionnaires and statistical approaches used [50]
Cluster trial using administrative data	Explain linkage of nutritional intervention data with administrative outcomes (e.g., healthcare utilization) [48]	Provide rationale for selecting specific quality of life instruments and their relevance to nutritional intervention [49]

Experimental Protocols and Implementation

Protocol for Implementing CONSORT-ROUTINE in Nutrition Trials

Objective: To ensure complete reporting of routine data elements in nutritional intervention trials.

Methodology:

• Data Source Documentation: Document the original purpose of the routine data source, frequency of data collection, and known data quality issues, particularly for nutritional variables [48].
• Linkage Methodology: Describe the linkage process for connecting trial participants with routine data, including matching variables and linkage error rates [48].
• Representativeness Assessment: Compare baseline characteristics of trial participants with eligible non-participants from the same data source to assess selection bias [48].
• Variable Specification: Clearly distinguish between variables collected specifically for the trial and those obtained from routine data sources [48].

Protocol for Implementing CONSORT-PRO in Nutrition Trials

Objective: To ensure valid and transparent reporting of patient-reported outcomes in nutritional intervention trials.

Methodology:

• PRO Hypothesis Specification: Pre-specify PRO hypotheses, including timing of assessment and definition of clinically important differences specific to nutritional outcomes [49].
• Instrument Validation: Report evidence of validity and reliability for PRO instruments in the study population, including cultural adaptation when necessary [49].
• Missing Data Management: Implement and report strategies to minimize missing PRO data, with statistical methods to handle unavoidable missingness [50].
• Interpretation Framework: Provide interpretation guidelines for PRO results, including reference to minimal important differences and clinical significance in the context of nutritional outcomes [49].

Integrated Quality Assessment Protocol

Objective: To evaluate adherence to both CONSORT-ROUTINE and CONSORT-PRO elements in nutritional intervention trials.

Methodology:

• Checklist Development: Create an integrated checklist combining relevant items from both extensions tailored to nutrition-specific considerations.
• Pilot Testing: Apply the checklist to a sample of published nutrition trials to identify common reporting gaps.
• Stakeholder Feedback: Solicit input from nutrition researchers, methodologies, and journal editors on utility and feasibility.
• Refinement Process: Revise the checklist based on feedback and validation against methodological standards.

Visualization of Framework Relationships

CONSORT Extensions Relationship to Nutrition Research

Table 3: Key Research Reagent Solutions for Implementation

Resource Category	Specific Tools/Resources	Application in Nutrition Research
Reporting Guidelines	CONSORT-ROUTINE Checklist, CONSORT-PRO Checklist, CONSORT 2025 Statement [47] [48] [49]	Foundation for comprehensive trial reporting; ensures methodological transparency
Protocol Development	SPIRIT 2013 Statement, SPIRIT-PRO Extension [47] [50]	Guides pre-specification of outcomes, analysis methods, and PRO hypotheses in trial protocols
PRO Instrument Libraries	PROMIS, NIH Toolbox, PROQOLID [49]	Provides validated measures for nutrition-relevant PROs like gastrointestinal symptoms, fatigue, and quality of life
Data Linkage Tools	Privacy-preserving record linkage systems, data validation frameworks [48]	Enables integration of nutritional trial data with routine healthcare data while maintaining privacy
Quality Assessment Tools	CONSORT-ROUTINE adherence checklist, CONSORT-PRO evaluation criteria [50]	Allows self-assessment of reporting completeness prior to manuscript submission

The relationship between CONSORT-ROUTINE and CONSORT-PRO represents a complementary framework for enhancing methodological reporting in specialized trial designs. For nutritional intervention research, both extensions provide valuable guidance for addressing specific methodological challenges, though their application must be adapted to nutrition-specific contexts.

The ongoing development of CONSORT-Nut, a nutrition-specific CONSORT extension, represents an important future direction for the field [15] [45]. This initiative, collaboratively led by the Federation of European Nutrition Societies and the STAR-NUT working group, aims to consolidate reporting guidance specific to nutritional interventions [15]. The development process has included Delphi surveys and pilot testing with diverse nutrition trials, suggesting that the resulting extension will incorporate relevant elements from both CONSORT-ROUTINE and CONSORT-PRO while adding nutrition-specific reporting standards [45].

For current practice, nutrition trialists should implement both extensions where applicable while maintaining adherence to the core CONSORT 2025 statement. This integrated approach will enhance reporting quality and facilitate the interpretation and application of nutrition trial results to inform clinical practice and public health policy.

The formulation of effective human nutrition policy relies on a robust evidence base generated from high-quality randomized controlled trials (RCTs). Inadequate or non-standardized reporting of these trials hinders the reproducibility, interpretation, and application of results for researchers, scientists, and drug development professionals [13]. While the Consolidated Standards of Reporting Trials (CONSORT) guidelines have significantly strengthened trial reporting since their introduction in 1996, RCTs in nutrition face unique complexities that require specialized reporting considerations [15].

Nutritional interventions are inherently complex compared to pharmaceutical trials. Participants have highly heterogeneous background diets and nutritional statuses that influence intervention responses, making it difficult to establish true control groups. Additionally, dietary substitutions often affect multiple nutrients simultaneously, and blinding is frequently challenging, especially for whole-foods interventions [10] [13]. These nuances necessitate tailored reporting guidance beyond standard CONSORT recommendations.

Recognizing this need, the Federation of European Nutrition Societies (FENS) established a working group in 2020 as part of its "Improving Standards in the Science of Nutrition" initiative [13]. This group has led an international effort to develop a CONSORT extension specific to nutrition RCTs (CONSORT-Nut), collaborating with the STAR-NUT (Supporting Transparency And Reproducibility in studies of NUTritional interventions) working group hosted within the EQUATOR network to consolidate reporting standards for nutritional intervention research [15]. This application note details the consensus-building methodologies and stakeholder feedback shaping the forthcoming CONSORT-Nut guidelines.

Stakeholder Engagement and Consensus Methodologies

Delphi Survey for Structured Stakeholder Feedback

A Delphi survey was conducted to gather formal, structured feedback from the global nutrition research community on the proposed CONSORT extension for nutrition trials [11] [13]. This systematic methodology enabled the collection and synthesis of expert opinions to build consensus on the reporting checklist items.

Table 1: Delphi Survey Participant Demographics and Expertise

Characteristic	Category	Participants (n=46)	Percentage
Gender	Female	28	61%
	Male	18	39%
Geographic Distribution	Europe	17	37%
	North America	7	15%
	Africa	5	11%
	Asia	4	9%
	Australia/New Zealand	3	7%
Expertise Areas	RCT design and conduct	8	17%
	Nutrition and diet studies	7	14%
	Public health nutrition	3	6%
	Nutrition epidemiology	4	9%
	Maternal and child health	3	6%

The Delphi process employed a multi-round design with predetermined agreement thresholds [13]. In the first round, participants evaluated 32 proposed items using a Likert scale and provided qualitative comments through open-ended questions. Items achieving ≥80% agreement ("agree" or "strongly agree") were retained, while others were revised or merged based on quantitative results and thematic analysis of feedback. The second round presented a refined 29-item checklist using dichotomous (yes/no) questions to confirm consensus.

Table 2: Delphi Survey Results and Agreement Rates

Survey Round	Items Presented	Response Rate	Items Achieving ≥80% Agreement	Key Actions
Round 1	32 items	38/47 (80%)	23/32 (72%)	3 items dropped or merged based on feedback
Round 2	29 items	36/38 (78%)	29/29 (100%)	Consensus achieved, no third round needed

The Delphi process successfully established consensus on all 29 proposed checklist items, with 100% achieving the predefined agreement threshold in the second round [13]. This high level of agreement across a diverse international stakeholder group demonstrates strong community support for the CONSORT-Nut extension.

Complementary Consensus-Building Activities

Beyond the formal Delphi survey, the FENS working group employed additional methodologies to gather comprehensive stakeholder feedback and refine the proposed extension.

The World Café method was utilized during the International Union of Nutritional Sciences International Congress of Nutrition 2022 (IUNS-ICN 22) to facilitate interactive discussions with participating nutrition scientists [9]. This participatory approach enabled dynamic refinement of the proposal through structured, rotating small-group conversations that captured diverse perspectives.

Pilot testing of the proposed checklist was conducted on eight nutrition trials of diverse designs to evaluate its practical application and identify reporting challenges in real-world scenarios [9]. This implementation testing provided evidence that reporting of nutrition trials could be improved through the dedicated extension.

Journal editor engagement provided valuable insights from stakeholders responsible for implementing reporting guidelines in publication workflows [9]. This feedback was instrumental in developing a potential tool specific to assessing adherence to the proposed nutrition extension checklist.

Figure 1: Stakeholder Consensus Development Workflow for CONSORT-Nut Extension. This diagram illustrates the multi-stage process used to gather and incorporate international feedback from the nutrition research community.

Experimental Protocols for Consensus Building

Delphi Survey Implementation Protocol

The Delphi survey followed a rigorous methodology to ensure robust, unbiased consensus development [13]. The protocol included:

Participant Identification and Recruitment: A diverse panel of 134 subject experts was identified through the authors' professional networks, purposefully selected to represent a comprehensive range of themes and disciplines in nutrition science. Potential participants were invited via email with informed consent and conflict-of-interest declaration forms.

Survey Administration: The first round survey was piloted with 10 PhD students and scientific assistants before live deployment. Participants received a two-week response window, extended to eight weeks to accommodate end-of-year holidays and extended leave. The survey platform collected responses anonymously to reduce bias from dominant individuals.

Data Analysis: Quantitative analysis utilized Microsoft Excel for calculating agreement percentages, while qualitative analysis of open-ended comments employed Microsoft Word to identify themes and suggestions. Missing data points (1% across all items) were allocated a "neither agree nor disagree" rating to maintain data integrity.

World Café Method Protocol

The World Café session at IUNS-ICN 22 followed this structured protocol [9]:

Session Design: Multiple small discussion tables were arranged with 4-5 participants each, with a trained table host facilitating conversations. Each table focused on specific aspects of the proposed CONSORT extension.

Progressive Rounds: Participants rotated between tables in three 20-minute rounds, allowing cross-pollination of ideas while maintaining continuity through table hosts who remained at their stations.

Harvesting Insights: Key insights from each table were visually recorded on tablecloths or flip charts. A final plenary session synthesized emerging themes, patterns, and recommendations for checklist refinement.

Table 3: Research Reagent Solutions for Nutrition Trial Reporting and Consensus Development

Tool/Resource	Function/Application	Implementation Context
CONSORT-Nut Checklist	Standardized reporting framework for nutrition-specific trial elements	29-item extension to CONSORT for nutrition RCT protocols and publications
Delphi Method Toolkit	Structured multi-round survey technique for expert consensus building	Gathering quantitative and qualitative feedback from distributed stakeholder groups
Rayyan Platform	Collaborative systematic review management for evidence synthesis	Initial scoping reviews to identify reporting gaps in nutrition literature [51]
Mixed Method Appraisal Tool (MMAT)	Critical quality assessment of diverse study methodologies	Evaluating methodological quality of studies informing consensus decisions [51]
ACCORD Guidelines	Reporting standards for consensus methods in biomedicine	Ensuring transparent documentation of Delphi methodology and outcomes [13]
World Café Method	Participatory, interactive approach for stakeholder engagement	Facilitating dynamic small-group discussions at scientific conferences [9]

Future Implementation and Adoption

The CONSORT-Nut extension represents a significant advancement in standardization for nutrition research, with planned implementation throughout the scientific community [10]. Following finalization of the checklist through a consensus meeting, the working group will focus on dissemination and training to ensure widespread adoption.

Journal editors representing major nutrition publications have expressed enthusiasm for implementing the extension once finalized [10]. The working group plans to collaborate directly with journals to promote adoption, with anticipated implementation in 2026. This editorial support is crucial for successful integration into manuscript submission and review processes.

To build researcher capacity, the initiative will develop freely available online tools for use in higher education systems, enabling research supervisors and lecturers to incorporate the extension throughout the trial process [10]. Additional knowledge translation activities will include webinars and conference sessions to provide practical guidance on applying the new reporting standards.

The adoption of CONSORT-Nut is expected to enhance the credibility of nutrition RCTs by ensuring sufficient methodological detail for rigor and reproducibility [10]. This improved reporting quality will facilitate more inclusive systematic reviews, enhance risk of bias assessment, and increase potential for meta-analyses, ultimately strengthening the evidence base for nutrition policy and clinical practice.

The development of the CONSORT extension for nutrition trials demonstrates the value of structured, international stakeholder engagement in establishing robust methodological standards. Through systematic consensus-building methodologies including Delphi surveys, World Café discussions, and practical pilot testing, the nutrition research community has established a comprehensive reporting framework that addresses the unique complexities of nutritional interventions.

This collaborative initiative, spearheaded by FENS in partnership with STAR-NUT and the EQUATOR network, exemplifies how transnational cooperation can enhance research quality and transparency. The resulting CONSORT-Nut guidelines will fill a critical gap in nutrition science reporting, potentially increasing public trust in nutrition research and strengthening the evidence base for public health policy and food product innovation.

The successful consensus process documented in this application note provides a replicable model for developing methodological standards across scientific disciplines, emphasizing the importance of diverse stakeholder engagement, methodological rigor, and practical implementation planning.

The credibility and ultimate utility of any scientific reporting guideline are fundamentally rooted in the transparency and rigor of its development process. Within the specific context of creating Consolidated Standards of Reporting Trials (CONSORT) extensions for nutritional intervention trials, employing a structured, pre-defined, and multi-stakeholder methodology is paramount. Such an approach ensures that the resulting checklist is robust, evidence-based, and widely accepted by the research community it aims to serve. The development of a CONSORT extension is a formal undertaking that typically follows established pathways for health research reporting guidelines, incorporating a mix of empirical evidence, expert consensus, and public feedback. This document outlines the application notes and detailed protocols for employing these transparent development methodologies, providing a framework for the creation of a CONSORT extension tailored to the unique complexities of nutrition trials.

Core Development Workflow and Stakeholder Engagement

The development of a credible reporting guideline follows a multi-stage, iterative process designed to incorporate diverse inputs and build consensus. The workflow, from project initiation to post-publication dissemination, is visualized below, highlighting the key phases and the involved stakeholders.

Figure 1: Guideline Development Workflow and Key Stakeholders. This diagram illustrates the sequential phases of developing a CONSORT extension and the critical stakeholder groups engaged throughout the process to ensure credibility and wide adoption.

Application Notes for Workflow and Engagement

• Iterative, Not Linear: The process is iterative rather than strictly linear. Phases may overlap, and findings from later stages (e.g., the Delphi process) may necessitate a return to earlier stages (e.g., further literature review) [52].
• Stakeholder Diversity: Engaging a wide range of stakeholders from the beginning is critical for ensuring the guideline's relevance and acceptance. This includes the official CONSORT Group for methodological alignment, journal editors and funders for future endorsement, and content experts (nutrition scientists) for domain-specific validity [52] [9]. The inclusion of patient representatives, as seen in the CONSORT 2025 update, is an emerging best practice [1].
• Defined Leadership: Establishing a core, multidisciplinary working group at the project launch is essential to steer the initiative, manage communications, and drive the project forward [52].

Quantitative Data from Development Processes

The credibility of a guideline is reinforced by the quantitative data gathered during its development, particularly concerning participant engagement and consensus achievement in the Delphi process. The following tables summarize typical data from such endeavors.

Table 1: Delphi Survey Participation Metrics from Guideline Development Projects

Development Project	Invited Participants	Round 1 Completers	Round 2 Completers	Consensus Threshold	Reference
CONSORT Extension for Nutrition Trials	138	38	36	≥80% agreement	[11]
CONSORT 2025 Update	Not Specified	317	290 (Round 3)	Not Specified (Delphi informed consensus meeting)	[1]
CONSORT Extension for Pilot Feasibility Trials	Not Specified	Not Specified	Not Specified	≥80% agreement	[52]

Table 2: Delphi Survey Outcomes for a CONSORT Nutrition Extension

Delphi Round	Initial Items	Items Achieving Consensus	Subsequent Action	Reference
Round 1	32	23 (72%)	3 items dropped or merged	[11]
Round 2	29	29 (100%)	No third round required	[11]
Final Checklist	29 items			[11]

Application Notes on Quantitative Data

• Representative Sampling: Invitations for the Delphi process should be strategically distributed to ensure a representative spread of expertise, geography, and stakeholder roles to minimize bias [11] [1].
• Pre-defined Consensus: The consensus threshold (commonly ≥70-80%) must be defined a priori to ensure objectivity in determining which items are retained [11] [52].
• High Retention Rates: High completion rates between Delphi rounds (e.g., 95% retention between Rounds 1 and 2 in the nutrition extension) indicate strong stakeholder engagement and reduce the risk of participation bias [11].

Experimental Protocols for Key Development Phases

Protocol 1: Conducting a Delphi Survey for Consensus Building

Purpose: To systematically solicit and aggregate expert opinions on potential checklist items, with the goal of achieving formal consensus.

Methodology Details:

• Participant Recruitment: Identify and invite a broad panel of experts (e.g., 138 participants for the nutrition extension). The panel should include nutrition scientists, trial methodologies, statisticians, journal editors, and clinical researchers [11] [52].
• Survey Rounds:
  • Round 1: Present the initial list of candidate items, often derived from a literature review. Participants rate their agreement on the inclusion of each item using a Likert scale (e.g., 1-5 or 1-9) and provide free-text comments for each item [11] [52].
  • Analysis and Revision: After Round 1, calculate the percentage agreement for each item. Items meeting the pre-specified consensus threshold (e.g., ≥80%) are retained. Items below the threshold are revised, merged, or dropped based on qualitative comments. This process resulted in the reduction from 32 to 29 items in the nutrition extension [11].
  • Round 2: Present the revised checklist. Participants typically re-rate the items using a dichotomous scale (include/exclude) and provide further comments. Items meeting the consensus threshold in this round are included in the final checklist [11].
• Stopping Criteria: The Delphi process can be concluded when a pre-specified level of consensus is achieved for all items, or after a pre-determined number of rounds (e.g., two rounds were sufficient for the nutrition extension) [11].

Protocol 2: Hosting a Consensus Meeting

Purpose: To bring together a representative group of stakeholders for a focused discussion on the Delphi results, to debate contentious items, and to finalize the checklist.

Methodology Details:

• Participant Selection: Invite a subset of 20-30 international experts from the Delphi panel, ensuring representation of all key stakeholder groups [52] [1].
• Pre-Meeting Materials: Circulate the results of the Delphi survey, including quantitative scores and a summary of qualitative comments, to all meeting participants in advance [1].
• Meeting Facilitation: Conduct a structured meeting, either in-person or online. The meeting should:
  • Discuss each checklist item, with special attention to those that did not achieve consensus or generated mixed comments during the Delphi process.
  • Use anonymous real-time polling (e.g., via Zoom) to gauge agreement on contentious points when discussion indicates differing opinions [1].
  • Aim to reach a final consensus on the wording and inclusion of every item in the draft checklist.
• Post-Meeting Follow-up: Circulate the finalized checklist draft to all consensus meeting participants for final confirmation and to ensure the document accurately reflects the group's decisions [1].

Protocol 3: Developing an Explanation & Elaboration (E&E) Document

Purpose: To create a comprehensive companion document that provides the rationale, justification, and examples of good reporting for each item in the checklist, which is critical for implementation.

Methodology Details:

• Content Generation: For each checklist item, the E&E document should include:
  • A detailed description of what the item means and its importance.
  • The rationale for its inclusion, supported by empirical evidence from the scoping review or theoretical arguments.
  • Examples of good reporting extracted from published, high-quality nutrition trials [53].
• Piloting: Pilot the draft checklist and E&E document on a series of published nutrition trials of diverse designs to ensure clarity, applicability, and comprehensiveness. This step was used to refine the nutrition extension proposal [9].
• Publication Strategy: The E&E document should be published as a separate, open-access manuscript in a peer-reviewed journal to ensure it is freely available to the global research community [1] [53].

The Scientist's Toolkit: Essential Reagents for Guideline Development

Table 3: Key Research "Reagents" and Methodological Tools for Developing a CONSORT Extension

Tool / Reagent	Function in Development Process	Application Notes
EQUATOR Network Methodological Framework	Provides a standardized protocol for developing health research reporting guidelines, ensuring completeness and rigor.	Serves as the foundational recipe for the entire project, from planning to dissemination [1].
Evidence Database (e.g., SCEBdb)	A project-specific database for storing and synthesizing empirical and theoretical evidence related to reporting quality and biases.	Used to generate an evidence-based list of potential checklist items and to support rationale in the E&E document [1].
Online Delphi Survey Platform	A web-based tool (e.g., SurveyMonkey, Qualtrics) to administer multiple rounds of the Delphi survey to a distributed expert panel.	Enables efficient data collection and analysis of quantitative and qualitative feedback from a large, international group [11] [52].
Consensus Meeting Facilitation Tools	Software for virtual meetings (e.g., Zoom) with integrated polling features to facilitate anonymous voting and real-time decision-making.	Critical for achieving final agreement, especially when managing a geographically dispersed panel [1].
Pilot Testing Corpus	A curated set of published trial reports (e.g., 8 diverse nutrition trials) used to test the draft checklist.	Provides real-world evidence of the checklist's utility and identifies areas where item wording may be ambiguous or incomplete [9].

Conclusion

The development of CONSORT-Nut represents a pivotal advancement for nutritional science, addressing long-standing reporting challenges that have hampered evidence synthesis and clinical application. By providing tailored guidance for the unique complexities of dietary interventions, this extension will enhance the transparency, reproducibility, and overall quality of nutrition research. The collaborative, evidence-based approach taken by FENS and the EQUATOR Network ensures broad stakeholder buy-in and practical applicability. Looking forward, successful implementation of CONSORT-Nut will empower researchers to generate more reliable evidence, ultimately strengthening nutritional guidelines and improving public health outcomes. Future directions include monitoring guideline adoption, assessing its impact on reporting quality, and planning for subsequent updates as nutritional research methodologies evolve.

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