Environmental Impact of Diets

Not only do today’s most popular diets have differences in their nutrition ethos, but they also have notable differences in their environmental impact. The research, published in The American Journal of Clinical Nutrition, compiled data from more than 16,000 adult diets collected by the CDC’s National Health and Nutrition Examination Survey.

A team from Tulane University compared popular diets on both nutritional quality and environmental impact and found that vegan and vegetarian diets produced the least amount of carbon dioxide. More meat-centric keto and paleo diets—as typically eaten by American adults—ranked lowest in terms of sustainability and overall diet quality. The keto diet, which prioritizes consuming high amounts of fat and low amounts of carbs, was estimated to have the biggest carbon influence generating almost 3 kilograms of carbon dioxide for every 1,000 calories consumed.

On the other end of the spectrum, a vegan diet was found to be the least impactful on climate, generating .7 kg of carbon dioxide per 1,000 calories consumed. The pescatarian diet, where more of the animal-based protein comes from fish, scored highest for nutritional quality of the diets analyzed, with vegetarian and vegan diets following behind. The omnivore diet—the most common diet, represented by 86% of survey participants—sat squarely in the middle of the pack of both quality and sustainability. When those on the standard American omnivorous diet opted for the plant-forward Mediterranean or DASH diets, both carbon footprints and nutritional quality scores improved.

See also: Reducing Our Food-Related Carbon Footprint