Climate change: we are what we eat.

• Position: Global Warming

You are what you eat, as the saying goes, and while good dietary choices boost your own health, they also could improve the health care system and even benefit the planet. Healthier people mean not only less disease, but reduced greenhouse gas emissions from health care. As it turns out, some relatively small diet tweaks could add up to significant inroads in addressing climate change, maintain researchers who analyzed the potential effects of healthier model diets for the U.S. The results appear in Climatic Change.

The food system contributes about 30% of total U.S. greenhouse gas emissions, with the largest proportion coming from animal-based food. In addition, the poor quality of the standard U.S. diet--including high levels of red and processed meat and low levels of fruits and vegetables--is a major factor in a number of preventable diseases. The U.S. spends three trillion dollars on health care every year--18% of the gross domestic product--much of it allocated to diseases associated with poor diets.

Geography researcher and study director David Cleveland and colleagues first used data from published meta-analyses that examined the effect of foods on diseases. Then, using life-cycle assessment data for the foods that changed in the healthier model diets, they analyzed the effects of the diets on greenhouse gas emissions for the food system.

For the health care system, they estimated the change in risk of diabetes, colorectal cancer, and coronary heart disease due to the healthier diets and the subsequent effect on both health care costs and greenhouse gas emissions.

To create healthier model diets, the researchers altered the standard 2,000-calorie-a-day U.S. diet, changing the sources of about half of those calories. The different model diets progressively reduced the amount of red and processed meats, with the most stringent diet eliminating them completely. Fruit and vegetable intake was doubled, and peas and beans increased to replace the meat...