Representation of diet and mental health evidence in national dietary guidelines and large-scale public health nutrition programmes

Abstract Background Common mental health disorders contribute to global disability, yet improving mental health outcomes is rarely a goal of nutrition policy. There is emerging evidence that links food insecurity, diet quality, ultra-processed foods, and microbiota-gut-brain pathways with mental health. This policy document analysis examined how evidence on the relationship between diet and mental health is reflected in national dietary guidelines and large-scale nutrition and social protection programme documents. Methods Using Population-Concept-Context criteria and document analysis procedures guided by Arksey and O’Malley and Joanna Briggs Institute, and PRISMA extension for scoping review reporting principles, we identified selected national food-based dietary guidelines and flagship programme or policy documents (2000–March 2026) and examined whether and how they contained language related to mental health. These documents were retrieved from the portals of the Food and Agriculture Organization of the United Nations and the United Nations Children’s Fund, UN agency repositories, and national or federal websites. The sample was multi-region but not an exhaustive census of all national dietary guidelines globally. We then synthesised data descriptively on characteristics, mental health framing, indicators, mechanisms, and equity. Results Nineteen documents met the criteria, including nine national guidelines, one global FBDG review, and nine programme and policy documents. Most documents were ‘silent’ or ‘symbolic’, using generic language about well-being or learning without clearly mentioning mental health outcomes, indicators, or mechanisms. The only exceptions were the U.S. National Strategy on Hunger, Nutrition, and Health and the Rural Health Produce Prescription Toolkit, which showed emergent integration by linking food insecurity to anxiety, depression, and toxic stress. Conclusion The science of the link between diet and mental health remains largely absent from formal nutrition guidance. Future revisions to guidelines and programmes should incorporate mental health outcomes and shared indicators across diverse high- and low-income settings.