Food emissions taxes can deliver health and environmental benefits with limited leakage.

Exploring various designs of greenhouse gas (GHG) taxation in food systems is crucial for understanding possible global implications. Here we investigate cross-product substitution and cross-country reallocations derived from food-consumption-based GHG taxes, together with their mitigation and health effects. We vary the tax scenarios according to the social cost of carbon (SCC) used to calculate the country-specific tax rate, the international diffusion of the tax, and the use of within-country tax revenue recycling to subsidize fruit and vegetables. We find that, despite minor leakage risks, a uniform-SCC approach offers the highest global mitigation potential but could harm health in some countries. SCC scenarios reflecting common but differentiated responsibility lower mitigation but lessen the negative health effects, and subsidies can improve health but lower mitigation. Our findings support an ambitious GHG tax for improving mitigation and health, provided it does not substantially reduce purchasing power.