People who eat a healthy, sustainable diet can significantly reduce their risk of premature death, in addition to their impact on the environment, according to a new study led by the Harvard TH Chan School of Public Health. It is the first major study to directly evaluate the impact of adhering to the recommendations from the groundbreaking 2019 EAT-Lancet report. The researchers used the dietary pattern outlined in the report – which emphasizes a variety of minimally processed plant-based diet, but allows modest consumption of meat and dairy products – called the Planetary Health Diet (PHD).
The research will be published online on June 10 The American Journal of Clinical Nutrition.
“Climate change is putting our planet on a path toward ecological disaster, and our food system plays an important role,” said corresponding author Walter Willett, professor of epidemiology and nutrition. “Changing the way we eat can help slow the process of climate change. And what's healthiest for the planet is also healthiest for people.”
While other studies have found that diets that emphasize plant foods over animal foods can have benefits for the health of people and the planet, most have used one-time nutritional assessments, which yield weaker results than looking at diets over a long period of time. period of time.
The researchers used health data from more than 200,000 women and men who participated in the Nurses' Health Study I and II and the Health Professionals Follow-Up Study. The participants were free of serious chronic diseases at the start of the study and completed nutritional questionnaires every four years for up to 34 years. Participants' diets were assessed based on intake of 15 food groups – including whole grains, vegetables, poultry and nuts – to quantify adherence to the PHD.
The study found that the risk of premature death was 30% lower in the top 10% of participants who were most compliant with the PHD, compared to those in the bottom 10%. Every major cause of death, including cancer, heart disease and lung disease, was lower with greater adherence to this diet.
Additionally, the researchers found that those with the highest compliance with the PHD had significantly lower environmental impacts than those with the lowest compliance, including 29% lower greenhouse gas emissions, 21% lower fertilizer needs, and 51% lower cropland use.
The researchers noted that land use reduction is especially important as a facilitator of reforestation, which is seen as an effective way to further reduce the levels of greenhouse gases that cause climate change.
“Our study is notable given that the U.S. Department of Agriculture has refused to consider the environmental impacts of dietary choices, and any reference to the environmental impacts of diet will not be allowed in the upcoming revision of the U.S. Dietary Guidelines,” said Willett. “The findings show how connected human and planetary health are. Healthy eating increases environmental sustainability – which in turn is essential for the health and well-being of every person on earth.”
Other Harvard Chan School authors included Linh Bui, Fenglei Wang, Qi Sun, Frank Hu, Kyu Ha Lee, and Marta Guasch-Ferre.
The study was funded by National Institutes of Health (NIH) research grants UM1 CA186107, P01 CA87969, R01 HL034594, U01 CA176726, U01 CA167552, R01 HL035464, R01 DK120870, and R01 DK126698.
“Planetary Health Diet Index and Risk of Total and Specific Mortality in Three Prospective Cohorts”, Linh P. Bui, Tung T. Pham, Fenglei Wang, Boyang Chai, Qi Sun, Frank B. Hu, Kyu Ha Lee, Marta Guasch-Ferre , Walter C. Willett, The American Journal of Clinical Nutrition, June 10, 2024, doi: 10.1016/j.ajcnut.2024.03.019
