Environmental impacts and monetary costs of healthy diets worldwide

Using real-world food price and greenhouse gas emissions data for locally available food items in 171 countries, we measure how healthy diets could be obtained with the lowest possible emissions, compared with costs and emissions of the least expensive options and foods most commonly consumed. We find that foods with the lowest greenhouse gas emissions for a healthy diet would emit 0.67 kgCO₂e. A healthy diet using the least expensive items in each country would emit 1.65 kgCO₂e and cost US$3.68 in 2021, while using foods most commonly consumed would emit 2.44 kgCO₂e and cost US$9.96. Animal-source foods and starchy staples account for 91% of the difference in emissions between the lowest-cost and lowest-emission diets. Other food groups, especially fruits and vegetables, vary widely in cost but not in emissions. Results show how changes in food policy and choice can most cost-effectively support healthier and more sustainable diets worldwide.