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Closely following a planet-friendly diet of mostly fruits, vegetables and whole grains reduces the risk of premature death by nearly one-third in people, while also dramatically cutting the release of greenhouse gases devastating the planet, a new study found.
“Eating more whole plant foods, less animal foods, and less highly processed foods is better for people and planet alike,” said Dr. David Katz, a specialist in preventive and lifestyle medicine who was not involved in the study.
“In this paper, we see that same message amplified: adhering to a dietary pattern conducive to the health of the planet and sustainability is associated with meaningful reductions in all-cause mortality,” he said in an email. Katz is the founder of the nonprofit True Health Initiative, a global coalition of experts dedicated to evidence-based lifestyle medicine
Food production plays a major role in the climate crisis. Raising livestock for human consumption, for example, uses an enormous amount of agricultural land and contributes to deforestation, biodiversity loss and water pollution, experts say.
Animals that chew their cud can emit noxious gases with an astounding impact on the environment. Burps and poo from cattle, sheep and goats generate methane, a greenhouse gas 80 times more powerful than carbon dioxide in warming the planet in the span of 20 years, according to the UN Environment Programme.
One adult cow, for example, can belch or fart up to 500 liters of methane a day. Add them up, and they can generate nearly 15% of total global greenhouse gas emissions, experts say.
Eating a planet-healthy diet, however, cut land use by 51%, greenhouse gas emissions by 29% and fertilizer use by 21%, while also extending the lives of people, according to the study.
“Changing how we eat can help slow climate change, and fortunately what’s healthiest for the planet is also best for us,” said corresponding author Walter Willett, professor of epidemiology and nutrition at the Harvard T.H. Chan School of Public Health in Boston.
“For every major cause of death we looked at, there was a lower risk in people with better adherence to the planetary health diet,” Willett said.
A diet for people and the planet
In 2019, the EAT-Lancet Commission, composed of 37 leading scientists from 16 countries, created a diet with dual goals — maximizing human health while reducing the environmental impact of feeding billions of people.
The resulting meal plan stressed a higher consumption of a rainbow of fruits and vegetables, whole grains, legumes and other plant-based proteins while reducing meat and dairy to small portions.
The study, published Monday in The American Journal of Clinical Nutrition, analyzed dietary data gathered from more than 200,000 women and men to see how it matched up against the Eat-Lancet dietary guidelines.
All the people were enrolled in long-term government studies — the Nurses’ Health Study I and II and the Health Professionals Follow-Up Study — and had no major diseases when the research began. Every four years for 34 years, study participants filled out dietary questionnaires, providing researchers with an enormous amount of data.
Researchers then scored the diets based on the intake of 15 food groups. Foods that are good for the planet take fewer overall resources to grow and include whole grains, tubers, vegetables, whole fruits, legumes, soybean foods and unsaturated plant oils, such as olive oil.
Foods that require a large use of land, such as cattle, and to a lesser extent sheep, goats, pigs and poultry, were also measured, as was intake of added sugar, which has many known health risks.
While other studies have looked at the impact of the planetary health diet, none has matched the scope of this study, Willett said. “This is a substantially larger and much longer study which has repeated assessments of diet over more than three decades, which allows more statistical precision,” he said.
The top 10% of people who followed the Eat-Lancet planetary diet were 30% less likely to die prematurely from any cause than those in the bottom 10%, the study found.
In addition, those who most closely followed the planetary diet had a 28% lower risk of neurodegenerative mortality, a 14% lower risk of dying from cardiovascular disease, a 10% lower risk of dying from cancer and a 47% lower risk of dying from a respiratory disease, which applied to nonsmokers as well, Willett said.
“The findings show just how linked human and planetary health are. Eating healthfully boosts environmental sustainability — which in turn is essential for the health and well-being of every person on Earth,” he added.
