Looking for a diet that’s good not only for you but also for the planet? If so, go heavy on plant foods and easy on meat, two recent studies advise.
In one, published in the Journal of Health Services Research & Policy, researchers computed the “carbon footprints” of winter and summer menus at a hospital in Spain; the menus reflect the typical Spanish (Mediterranean-style) diet. They compared these numbers to carbon footprint calculations previously made by other researchers for food consumption in the U.S. and U.K. (where diets are more meat-based). Carbon footprints express the amount of greenhouse gas (GHG) emissions as carbon dioxide equivalents. Such gases contribute to climate change, with global agriculture and food production accounting for 25 to 30 percent of the emissions.
Calorie for calorie, the Spanish diet was found to have a significantly lower carbon footprint than the diets of the U.S. and U.K., with the differences largely attributed to the smaller amount of meat eaten in Spain. That’s not surprising, since beef production is known to emit far more GHGs (notably methane, produced in the rumen of cows as foods ferment) than the growing of vegetables and other plant foods.
“The consumption of meat, or specifically red meat, is the greatest contributor of GHG emissions from food consumption, and the U.S. is among the top countries in the world in terms of red meat consumption per capita,” the researchers said. In contrast, the Mediterranean diet is characterized by abundant plant foods and little red meat. The diet also comes closer to the eating pattern recommended by the World Health Organization.
In another paper, published in Nature, researchers reviewed more than 200 articles and 50 years of data from 100 countries to determine the global impact that recent dietary changes have had (and are projected to have) on both human health and the environment. As noted in the paper, not only has rising wealth and urbanization led to worldwide increases in consumption of processed foods, meats, and other unhealthy fare that contribute to chronic diseases, but these factors are also accelerating climate change. On the other hand, it’s not too late, the researchers said, to reverse or at least slow the damage by returning to diets that are more plant-based.
More specifically, they calculated that eating a Mediterranean, vegetarian, or pescetarian (with fish but no meat) diet significantly decreases the risk of diabetes and cancer, as well as deaths from heart disease—compared to a typical American omnivorous (animal and plant) diet. Moreover, if more people adopted these plant-based diets, food-related GHG emissions would be reduced by up to 55 percent, compared to an 80 percent higher level projected for 2050 if present global trends continue.
Particularly damaging is beef and lamb production, the researchers noted, which emits about 250 times more GHGs per gram of protein than the growing of legumes. Poultry, pork, fish, and dairy have lower emissions than beef and lamb. And meat that is sustainably produced (such as on land not suited for crops) has much less environmental impact than industrialized meat production and can even have benefits (as when manure is recycled back into the soil).
Bottom line: The health and environmental consequences of what we eat are complex and nuanced. While a plant-based diet is best overall for health and the environment, moderate amounts of animal foods can still be part of a healthy and eco-friendly diet, depending on how they are produced.
Keep in mind that your carbon footprint is based on other variables besides your food consumption, such as how you heat your home, how much electricity and gasoline you use, how often you fly, and how you handle your garbage. To see how big your carbon footprint is, check out the online calculator from UC Berkeley. Other good calculators are available from the EPA, the Nature Conservancy, and Carbon Independent.