Diet item details: reporting checklist for feeding studies measuring the dietary metabolome (DID-METAB Checklist): Explanation and elaboration report on the development of the checklist by the DID-METAB Delphi Working Group

Metabolomics is a post-genomic, systems-based discipline offering valuable applications in nutrition research, including the use of objective biomarkers to characterise dietary intake and metabolic responses more accurately. A scoping review identified the need for reporting guidance on dietary information in the form of a checklist to ensure reproducibility of human feeding studies that are measuring the diet-related metabolome. Here, we aimed to gain consensus on a core outcome set (COS) pertaining to diet-related item details (DID) and recommendations for reporting DIDs to inform development of a reporting checklist. The goal of this checklist is to guide researchers on the minimum level of content and detail required for reporting dietary information in human feeding studies measuring the metabolome. A two-stage online Delphi process encompassing five survey rounds with international experts in clinical trial design, feeding study intervention implementation, metabolomics, and/or human biospecimen analyses was conducted. A COS encompassing twenty-nine core DIDs and accompanying recommendations was developed across 5 domains: Dietary Intervention - Modelling (8 DIDs), Dietary Intervention - Implementation (3 DIDs), Dietary Assessment (9 DIDs), Adherence and Compliance Monitoring (4 DIDs), and Bias (5 DIDs). The reporting guideline (DID-METAB Checklist) was generated and accepted by the international expert working group in the final survey round. All experts agreed that relevant journals should include the checklist as a suggested reporting tool for relevant studies and/or used alongside existing reporting tools. This report provides examples, explanations and elaboration for each recommendation including examples from published literature and references. The DID-METAB Checklist will be a key tool to advance the standardised reporting for feeding studies assessing the metabolome. Implementation of this tool will enable the ability to better interpret data and ensure global utility of results for furthering the advancement of metabolomics in nutrition research and future precision and personalised nutrition strategies