Winter 2019

Eating for the Earth

Are the Dietary Guidelines for Americans sustainable?

Nicole Tichenor Blackstone, N12, NG16, who recently joined the Friedman School as an assistant professor, wanted to find out if the Dietary Guidelines for Americans were sustainable. So she analyzed the environmental impacts of the three diets the guidelines recommend: healthy U.S.-style, which includes meat; Mediterranean, which has the same amount of meat, plus twice as much seafood; and vegetarian, which calls for less protein overall, all of it from eggs and plants. Her results, published in The Lancet Planetary Health, showed that red meat was the top cause of climate change in the U.S.-style diet, driving 69 percent of its protein-related CO2 emissions. The Mediterranean diet was the biggest contributor to water pollution because it calls for more fish. And the clear overall winner for the environment? The vegetarian diet, which had a lower impact on almost everything, from CO2 emissions to water pollution.

In this chart, adapted from Blackstone’s paper, see how the three diets compare on six metrics. (Larger bars indicate more substantial impact.)

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