A planetary health diet lowers the risk of total mortality

A recent study in the American Journal of Clinical Nutrition evaluating the associations between planetary health diet index (PHDI) and mortality rates found that a higher PHDI, which is better for environmental health, reduces the risk of total and cause-specific mortality. Results from this study indicate that a transition toward a planetary health diet could improve human and environmental health.

A planetary health diet is very similar to the Mediterranean diet and is characterized by a high consumption of minimally processed plant foods and modest or minimal consumption of meat and dairy.

“Climate change has our planet on track for ecological disaster, and our food system plays a major role,” said corresponding author Walter Willett, MD, DrPH, professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health, in a press release. “Shifting how we eat can help slow the process of climate change. And what’s healthiest for the planet is also healthiest for humans.”

The researchers used data from the Nurses’ Health Study I and II to gather information on 66,692 and 92,438 females, respectively, and data from the Health Professionals Follow-up Study on 47,274 males. The study excluded individuals with cancer, diabetes, or major cardiovascular disease and calculated a PHDI every four years based on responses to a semiquantitative food frequency questionnaire.

The study identified 31,330 female deaths and 23,206 male deaths, evaluating how PHDI impacted mortality rates. A higher PHDI indicated greater adherence to the planetary health diet, while a lower score indicated the inverse.

According to the study, the risk of all-cause mortality was 23% lower in the group with the highest PHDI than those with the lowest PHDI. Additionally, a closer look at cause-specific mortality revealed a 14% lower risk of cardiovascular disease-related mortality and a 10% reduction in cancer-related mortality. Other insights found that a high PHDI was linked to a 47% lower risk of respiratory disease death and a 28% lower risk of neurodegenerative disease death.

Beyond that, a higher PHDI index in women was also linked to a 38% lower risk of death from infectious diseases.

“Our study is noteworthy given that the United States 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 US Dietary Guidelines,” added Willett. “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.”