Four ways blue foods can help achieve food system ambitions across nations

**Background:** Blue foods (aquatic animals, plants, and algae harvested from marine and freshwater environments) have been largely absent from global food system policy discussions, despite their diversity—over 2,200 wild species caught and more than 600 farmed. This paper synthesizes findings from the Blue Food Assessment, an initiative involving over 100 scholars, to articulate how blue foods can contribute to healthier, more equitable, and environmentally sustainable food systems. The authors identify four key functions of blue foods: (1) sources of critical nutrients (especially vitamin B12 and omega-3 fatty acids DHA and EPA), (2) healthy alternatives to terrestrial animal-source foods (particularly red meat), (3) nutrient sources with relatively low environmental footprints, and (4) cornerstones of cultures, diets, economies, and livelihoods.

**Methods:** The authors translate these four functions into policy objectives and map their relevance across nations using publicly available data and a crisp-set Boolean analysis. For each policy objective, proxy variables were selected (e.g., summary exposure values for nutrient deficiencies, red meat consumption levels, cardiovascular disease burden, greenhouse gas emissions from diets, blue food availability, climate hazard exposure). Thresholds for inclusion were set based on theoretical knowledge or natural breaks in the data, with sensitivity analyses conducted for all cutoff values. Countries were classified as 'highly relevant', 'relevant', or 'less relevant' for each policy objective. Overlap analysis assessed co-benefits between policy objectives.

**Key Results:** Fewer countries (43) were estimated to have >10% of their population at risk from inadequate vitamin B12 intake compared to omega-3 deficiency (89 countries), which predominantly affects African and South American nations. Countries with red meat intake above environmentally sustainable and healthy thresholds and high cardiovascular disease incidence are primarily in the global North plus several small-island states. A substantial number of countries (124) have high ruminant meat intake contributing to high dietary GHG footprints. Blue foods currently play important roles for nutrition, livelihoods, or national revenue in 103 countries, particularly in the global South. Overlap analysis shows that 91% of countries with vitamin B12 deficiencies also show high omega-3 deficiency. In 75% of the 89 countries where omega-3-enhancing policies are relevant, reducing environmental footprints is also relevant. For 82% of the 22 countries with high cardiovascular disease risk, promoting blue foods over red meat would simultaneously address health and environmental concerns.

**Clinical Implications:** Blue foods are rich in essential nutrients—projected to contribute a global average of approximately 27% of omega-3 fatty acids and 100% of vitamin B12 by 2030. Addressing these deficiencies is particularly important among vulnerable groups: young children, older people, pregnant women, and women of childbearing age. Blue foods can help circumvent the harmful nutrition transition by displacing red meat consumption, potentially reducing cardiovascular disease burden. However, the authors caution that simply adding blue foods to diets already rich in animal-source foods would undermine health and environmental goals. Substitutability of red meat by fish has not been well documented, though historical shifts from beef to poultry suggest feasibility. The paper emphasizes that realizing these clinical benefits requires policies ensuring affordability and access to low-environmental-impact blue foods, particularly for nutritionally vulnerable populations, while navigating trade-offs between domestic consumption and export revenues, and between environmental sustainability and nutritional content of aquaculture products.