Biodiverse diets present co-benefits for greenhouse gas emissions, land use, mortality rates and nutritional adequacy in Europe.

Dietary diversity is vital for public health nutrition, yet the co-benefits of increasing dietary species richness (DSR) on human and environmental health remain unassessed. Here we explore associations between DSR and greenhouse gas emissions, land use, nutrient adequacy and mortality rates among European Investigation into Cancer and Nutrition (EPIC) study participants. Total DSR was positively associated with probability of adequate nutrient intake diet scores and inversely related to mortality rates; similar results were observed for plant DSR. Animal DSR was inversely associated with probability of adequate nutrient intake diet scores and neutrally associated with mortality rates. Neutral associations for total DSR and positive associations for animal DSR were found with greenhouse gas emissions and land use. Conversely, plant DSR was inversely associated with greenhouse gas emissions and land use. These findings from Europe suggest modest benefits of dietary plant biodiversity for nutrient adequacy and environmental health, with stronger inverse associations with mortality rates, while highlighting the potential adverse environmental impacts of diets rich in animal-sourced foods.