Efficiency of dietary sustainability and its global transition

Global diets consume tremendous natural resources while causing multiple environmental and health issues. As the world faces challenges of adequate nutrition security with concomitant climate and environmental crises requiring urgent action, policies need to improve the efficiency of devoting environmental input of the food systems for health benefits. Here we evaluate the global transition of such efficiency in the past two decades represented by health benefits obtained by per unit of 4 key environmental inputs (GHG emissions, stress-weighted water withdrawal, acidifying emissions, and eutrophying emissions) in 195 countries. We find that the efficiency of each environmental input follows an N-shaped curve along the Socio-Demographic Index (SDI) gradient representing different development levels. The efficiency first increases by benefiting from the eliminated stunting with a larger abundance of food supply, then decreases driven by climbing environmental impacts from a shift to animal products, and finally starts to slowly grow again as countries shift toward a healthier diet. Our efficiency indicator offers an improved understanding of nutritional transitions in terms of environmental impacts and a useful way to monitor the transition of dietary patterns, set up policy targets, and evaluate the effectiveness of specific interventions.