Describing the landscape of nutrition- and diet-related randomized controlled trials: metaresearch study of protocols published between 2012 and 2022.

Gary S Collins, Michael Maia Schlussel, Sallie Lamb, Jennifer Anne de Beyer, Celeste Naude, Shaima Saleh, Flávia Moraes Silva, Leila Cheikh Ismail, Colby J Vorland, Neha Khandpur, Solange Durão, Gilberto Kac, Simone Bernardes, Shona Kirtley, Sally Hopewell, Matthew J Page, Cintia Curioni, Fabio S Gomes, Jonathan Cook, Amanda Rodrigues Amorim Adegboye

Journal: The American journal of clinical nutrition 2025;121(4):882-891

PMID: 39864593

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Abstract

BACKGROUND

Publishing protocols promotes transparency and reproducibility. The scope and methods of protocols for nutrition- and diet-related randomized controlled trials (RCTs) have not been investigated yet.

OBJECTIVES

This study aims to map the landscape of nutrition- and diet-related interventions research.

METHODS

We conducted a metaresearch of nutrition-and diet-related RCT protocols published between January 2012 and March 2022, in any language, targeting human participants, evaluating nutrition interventions isolated or combined. A systematic search of the literature was conducted in 6 online databases. Bibliometric information, study characteristics, and research transparency practices data were collected from the included publications. The instructions for authors of journals with publications in our sample were checked for endorsement of reporting guidelines. Mentions to reporting guidelines in the included protocols were also checked.

RESULTS

Among the 62,319 records retrieved, 1068 were eligible. The number of published protocols increased annually, with a mean of 103 (range: 32-163) publications/y. Protocols were published in 148 journals, 50 of them (33.8%) endorsed Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT), 111 (75.3%) Consolidated Standards of Reporting Trials (CONSORT), and 4 (2.7%) Template for Intervention Description and Replication (TIDieR), whereas 343 (32.1%) protocols mentioned SPIRIT, 297 (27.8%) CONSORT, and 20 (1.9%) TIDieR. Most protocols reported the RCT registration number (n = 1006; 94.2%) and included statements about conflicts of interest (n = 952; 89.1%) and funding (n = 994; 93.2%). About two-thirds of protocols focused on adults or elderly participants (n = 677; 63.4%). Most protocols described 1 isolated nutrition- or diet-related intervention (n = 724; 67.8%), which were most frequently "supplementation, supplements or fortification" (n = 405; 37.9%) or "nutrition education, counseling or coordination of care" (n = 354; 33.1%). The most frequent primary outcomes reported were related to clinical status (n = 308; 28.8%).

CONCLUSIONS

The number of protocols for nutrition- or diet-related RCTs published is increasing, supporting the raising awareness and the importance of promoting these publications. The support and mention of relevant reporting guidelines by journals and researchers, respectively, remain far from ideal.

Address: Nutrition Department and Graduate Program of Nutrition Science, Federal University of Health Science of Porto Alegre, Porto Alegre, Brazil.; Centre for Healthcare Research and School of Nursing, Midwifery and Health, Faculty of Health and Life Sciences, Coventry University, Centre for Agroecology, Water and Resilience, Coventry, United Kingdom.; Centre for Evidence-based Health Care, Department of Global Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.; Department of Nutrition in Public Health, University of the State of Rio de Janeiro, Rio de Janeiro, Brazil.; Pan-American Health Organization, World Health Organization, Washington, DC, United States.; UK EQUATOR Centre, Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom.; Nutritional Epidemiology Observatory, Department of Social and Applied Nutrition, Institute of Nutrition Josué de Castro, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.; Oxford Clinical Trials Research Unit, Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom.; Department of Clinical Nutrition and Dietetics, College of Health Sciences, University of Sharjah, Sharjah, United Arab Emirates; Nuffield Department of Women's & Reproductive Health, University of Oxford, Oxford, United Kingdom.; Methods in Evidence Synthesis Unit, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia.; Division of Human Nutrition and Health, Wageningen University, the Netherlands; Department of Nutrition, University of São Paulo, São Paulo, Brazil; Department of Nutrition, Harvard T.H. Chan School of Public Health, Harvard, Boston, MA, United States.; Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom.; Department of Clinical Nutrition and Dietetics, College of Health Sciences, University of Sharjah, Sharjah, United Arab Emirates.; Health Systems Research Unit, South African Medical Research Council, South Africa.; Department of Applied Health Science, Indiana University School of Public Health-Bloomington, Bloomington, IN, United States.; UK EQUATOR Centre, Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom. Electronic address: [email protected].

DOI: 10.1016/j.ajcnut.2025.01.016

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MeSH Terms: Randomized Controlled Trials as Topic, Humans, Diet