  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.
