Emma Bryce in Anthropocene Magazine: People who follow a diet rich in plants cut their mortality risk by almost a third, while simultaneously slashing the climate impact of their food by a similar amount. These results come from the largest study ever to analyze the health and environmental impacts of the widely-publicized EAT-Lancet Planetary Health Diet.
Launched in 2019, the EAT-Lancet Commission brought together reams of research to determine what would be the best way for us to eat on a global scale, to limit the environmental impacts of farming and food. The Commission came up with a diet rich in fruits, vegetables, whole grain and plant-sourced proteins, and lower in—but crucially not excluding—animal-sourced products like meat and dairy milk. That became known as the Planetary Health Diet. Until now, however, the benefits of this diet have been explored mainly on a small scale. The new study takes it up a notch. “This is by far the longest term, large study in actual people to look at both the human and planetary health benefits of the Planetary Health Diet,” says Walter Willett, the Fredrick John Stare professor of epidemiology and nutrition at the Harvard School of Public Health, and lead author on the research.
His new paper, published in The American Journal of Clinical Nutrition, relied on three pre-existing datasets that drew dietary information from over 200,000 American nurses over a 34-year period between 1986 to 2019. All participants were disease-free when the surveying started, and were required to complete a questionnaire every four years on the makeup of their diets.
To evaluate this vast trove of data, Willett and colleagues first selected 15 indicator foods that captured the span of dietary impacts, including whole fruits, vegetables, and nuts on the lower-impact end; and red meat, processed meat, and dairy on the higher-impact end. Then, they used these foods to develop an index that allowed them to score the nurses’ dietary surveys by how closely they aligned with the EAT-Lancet suggested Planetary Health Diet. Using a lifecycle-analysis, they estimated the environmental impacts of each reported diet according to those 15 indicator foods.
Because the study also recorded a varied set of health outcomes for the participants—everything ranging from cancer to diabetes, heart disease, lung disease, and neurodegenerative problems—this allowed Willett and team to correlate participants’ dietary trends with their health over the 34-year period.
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