A healthier US diet could reduce greenhouse gas emissions from both the food and health care systems

The standard US diet contributes to greenhouse gas emissions (GHGE) from both the food system, and from the health system through its contribution to non-communicable diseases. To estimate the potential for diet change to reduce GHGE and improve public health, we analyzed the effect of adopting healthier model diets in the USA on the risk of disease, health care costs, and GHGE. We found that adoption of healthier diets reduced the relative risk of coronary heart disease, colorectal cancer, and type 2 diabetes by 20-45%, US health care costs by US$B 77-93 per year, and direct GHGE by 222-826 kg CO(2)e capita(-1) year(-1) (69-84 kg from the health care system, 153-742 kg from the food system). Emission reductions were equivalent to 6-23% of the US Climate Action Plan's target of a 17% reduction in 2005 GHGE by 2020, and 24-134% of California's target of 1990 GHGE levels by 2020. However, there is potential for investment of health care savings to result in rebound up to and greater than 100%, which would increase net GHGE. Given the urgency of improving public health and of mitigating GHGE over the short term, the potential contribution of diet change, and the options for reducing rebound, deserve more research in support of policy.