科学美国人60秒:Nutrition Guidelines Healthy for the Planet, Too

You know those nutrition guidelines the government issues every few years? It turns out that following them isn’t just good for your health. It’s good for the planet, too.

“What we found is that impacts vary across nations, but in the high-impact nations, in general, you can see that, if you follow a nationally recommended diet, despite the fact that these diets don’t mention explicitly—or most of them don’t explicitly mention—environmental impacts, that you are going to have lower environmental impacts due to that. So that’s sort of fairly clear across all the high-income nations.”

Paul Behrens, an environmental scientist at Leiden University in the Netherlands. The food we eat takes a big toll on the environment. A third of the ice-free land on Earth is used for agriculture, and according to some estimates, producing food accounts for roughly a fifth of all human-caused greenhouse gas emissions. Fertilizer runoff also leads to other problems, like the algae blooms in Lake Eerie and the Dead Zone in the Gulf of Mexico.

However, following dietary guidelines would reduce those impacts, especially in wealthy countries like the US. “Most of the reductions come from meat and dairy,” which have an outsized impact on land use and pollution, and are a major source of greenhouse gases. (That’s partly due to cow farts. Seriously.) Heeding recommendations would also mean eating fewer calories, since many people here eat more than they need.

Overall, in high-income countries, Behren’s team estimates that following the rules could result in as much as a 17 percent reduction in land use, a 21 percent reduction in nutrient pollution, and a 25 percent drop in agricultural greenhouse gas emissions. Cutting down on how much food we waste—which is roughly a third in the U.S.—could help even more. The results are in the Proceedings of the National Academy of Sciences. [Paul Behrens et al., Evaluating the environmental impacts of dietary recommendations]

Of course, people are notoriously bad at following diets. But: “These nationally recommended guidelines do actually have a knock-on effect to other areas of policy making. So if I’m developing a new healthy-eating-for-schools program then that’s going to be based off a lot of detail that I get from the nationally recommended guidelines. So while it might not necessarily be the case that people follow directly…they actually are quite influential on the preparation of other advice.”

Seems that a smaller environmental footprint and a healthier lifestyle could go hand in hand.

—Julia Rosen