Country-specific dietary shifts to mitigate climate and water crises

TLDR

Undernutrition, obesity, climate change, and freshwater depletion are all driven by shared food and agricultural systems. Efforts to align dietary patterns with sustainability and health goals would benefit from country‑specific data covering the spectrum of over‑ and undernutrition. The authors modeled greenhouse‑gas and water footprints of nine increasingly plant‑forward diets, each meeting healthy‑diet criteria, for 140 countries. Across these countries, the modeled footprints varied widely due to local consumption, import patterns, and food‑chain intensities; diets with modest low‑food‑chain animal foods matched vegan footprints, and in 95 % of countries a single animal meal per day was less GHG‑intensive than lacto‑ovo vegetarian diets, yet modest plant shifts raised protein and caloric intake for under‑nourished populations, increasing overall footprints and highlighting the importance of trade, culture, and nutrition in diet‑footprint analyses.

Abstract

Undernutrition, obesity, climate change, and freshwater depletion share food and agricultural systems as an underlying driver. Efforts to more closely align dietary patterns with sustainability and health goals could be better informed with data covering the spectrum of countries characterized by over- and undernutrition. Here, we model the greenhouse gas (GHG) and water footprints of nine increasingly plant-forward diets, aligned with criteria for a healthy diet, specific to 140 countries. Results varied widely by country due to differences in: nutritional adjustments, baseline consumption patterns from which modeled diets were derived, import patterns, and the GHG- and water-intensities of foods by country of origin. Relative to exclusively plant-based (vegan) diets, diets comprised of plant foods with modest amounts of low-food chain animals (i.e., forage fish, bivalve mollusks, insects) had comparably small GHG and water footprints. In 95 percent of countries, diets that only included animal products for one meal per day were less GHG-intensive than lacto-ovo vegetarian diets (in which terrestrial and aquatic meats were eliminated entirely) in part due to the GHG-intensity of dairy foods. The relatively optimal choices among modeled diets otherwise varied across countries, in part due to contributions from deforestation (e.g., for feed production and grazing lands) and highly freshwater-intensive forms of aquaculture. Globally, modest plant-forward shifts (e.g., to low red meat diets) were offset by modeled increases in protein and caloric intake among undernourished populations, resulting in net increases in GHG and water footprints. These and other findings highlight the importance of trade, culture, and nutrition in diet footprint analyses. The country-specific results presented here could provide nutritionally-viable pathways for high-meat consuming countries as well as transitioning countries that might otherwise adopt the Western dietary pattern.