Our dietary choices may have environmental impacts, as certain foods require more water, can lead to more deforestation, and can have a higher output of greenhouse gas emissions. A recent study finds that making the decision to eat in more planet-friendly ways may also be better for our own personal health.

Researchers at Harvard T.H. Chan School of Public Health recently investigated mortality rates in people who adhere to a sustainable diet proposed by the EAT-Lancet Commission in 2019. Dubbed the Planetary Health Diet, it focuses on reducing food waste, improving agricultural practices, and stresses the consumption of a wide variety of minimally processed plant-based foods with smaller allowance for dairy and meat.

The researchers say there have been past studies on the health impacts of environmentally-friendly diets, but they were focused on outcomes at one point in time, rather than long term, which is what their study – published in The American Journal of Clinical Nutrition – investigated. The findings showed that overall adherence to this Planetary Health Diet was good for the planet, but it was also linked with lower all-cause mortality and lower rates of death from common diseases.

Walter Willett, study co-author and professor of epidemiology and nutrition at Harvard, says, “Climate change has our planet on track for ecological disaster, and our food system plays a major role. Shifting how we eat can help slow the process of climate change. And what’s healthiest for the planet is also healthiest for humans.”

To investigate the health impacts of the Planetary Health Diet, Willett and his team looked at data from nearly 160,000 women enrolled in two iterations of the Nurses’ Health Study and more than 47,000 men from the Health Professionals Follow-Up Study. At the time of enrollment, all were free from cancer, diabetes, and cardiovascular diseases.

These participants were followed for up to 34 years, and they completed dietary questionnaires every four years. Consumption of 15 food groups was studied, including whole grains, tubers, vegetables, fruits, red and processed meat, poultry, soy, non-soy legumes, and nuts.

The research showed that there was lower all-cause mortality in those with the highest adherence to the Planetary Health Diet, compared with the lowest adherence. Among the top 10%, the risk of premature death was 30% lower, compared with the lowest 10%. There was also a lower risk of death from cardiovascular diseases, cancer, respiratory diseases, and neurodegenerative diseases. In women, there was a lower risk of death from infectious diseases, as well.

The environmental impact of the diet was also shown, with the highest adherence linked with 29% lower greenhouse gas emissions, 21% lower fertilizer needs, and 51% lower cropland use. The researchers say their findings indicate that the Planetary Health Diet is linked with better health outcomes and a lower impact to the environment.

Willett says, “Our study is noteworthy given that the U.S. Department of Agriculture has refused to consider the environmental impacts of dietary choices, and any reference to the environmental effects of diet will not be allowed in the upcoming revision of the U.S. Dietary Guidelines. 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 wellbeing of every person on earth.”

If you’d like to read more about the diet, click here.