Affordability is often seen as a barrier to consuming sustainable diets. This study provides the first worldwide test of how retail food prices relate to empirically estimated environmental impacts and nutritional profile scores between and within food groups. We use prices for 811 retail food items commonly sold in 181 countries during 2011 and 2017, matched to estimated carbon and water footprints and nutritional profiles, to test whether healthier and more environmentally sustainable foods are more expensive between and within food groups. We find that within almost all groups, less expensive items have significantly lower carbon and water footprints. Associations are strongest for animal source foods, where each 10% lower price is associated with 20 grams lower CO2-equivalent carbon and 5 liters lower water footprint per 100kcal. Gradients between price and nutritional profile vary by food group, price range, and nutritional attribute. In contrast, lower-priced items have lower nutritional value in only some groups over some price ranges, and that relationship is sometimes reversed. These findings reveal opportunities to reduce financial and environmental costs of diets, contributing to transitions towards healthier, more environmentally sustainable food systems.
