Optimal Intake of Animal-Source Foods: A Scoping Review to Inform a New WHO Guideline.

Currently, the amount and types of animal-source foods that might be part of a healthy diet remain unclear. This scoping review was commissioned by the WHO for the development of a new guideline on optimal intake of animal-source foods and aimed to collect and describe the evidence available on animal-source foods and health outcomes. A systematic search of Embase, Medline, and PubMed, complemented with a search of recent nutrition guidelines, was conducted to identify systematic, scoping, and umbrella reviews published between 2019 and 2024. Reviews of prospective observational and interventional studies with participants ≥2 y from the general population, including pregnant women, assessing the effects of animal-source foods (red meat, poultry, fish, eggs, dairy) and as comparators selected protein-rich plant-source foods on any health outcome were included. Using a mining approach, prospective observational and interventional primary studies identified in the reviews were extracted. Research availability and gaps were depicted using evidence maps. From the 7458 records identified, a total of 652 reviews were included, encompassing 1626 eligible publications from 488 unique cohorts in 65 countries and 480 eligible publications from 387 unique trials in 37 countries. Single health outcomes were grouped together into 29 groups. The most often researched outcome groups were cancer, cardiovascular diseases, diabetes, body weight and composition, and all-cause mortality. Evidence gaps were identified in older adults, children, and pregnant women, in food-insecure settings, in Sub-Saharan Africa, Central and South East Asia. This scoping review offers a comprehensive overview of existing evidence on animal-source foods and health outcomes and identifies key research gaps to support the development of new nutrition guidelines.