New diet score reveals foods that help you live longer

According to new research, eating more foods that are good for the environment may help you live a longer, healthier life. In a study with a follow-up of more than 30 years, researchers discovered that those who ate more sustainably were 25 per cent less likely to pass away than those who didn't.

The research expands on earlier studies that identified foods that are beneficial to both human health and the environment, such as whole grains, fruit, non-starchy vegetables, nuts, and unsaturated oils, as well as foods that may be detrimental to both, such as eggs and red and processed meats. According to the latest research, consuming more healthful meals may lower one's risk of dying from conditions including cancer, heart disease, respiratory illnesses, and neurological disorders.

“We proposed a new diet score that incorporates the best current scientific evidence of food effects on both health and the environment,” said Linh Bui, MD, a PhD candidate in the Department of Nutrition at Harvard T.H. Chan School of Public Health. “The results confirmed our hypothesis that a higher Planetary Health Diet score was associated with a lower risk of mortality.”

Bui will present the findings at NUTRITION 2023, the flagship annual meeting of the American Society for Nutrition held July 22–25 in Boston.

According to existing evidence, plant-based foods are associated with both a lower risk of chronic diseases such as heart disease, colorectal cancer, diabetes, and stroke, and reduced impacts on the environment in terms of factors like water use, land use, nutrient pollution, and greenhouse gas emissions.

With the new study, the researchers aimed to create a simple tool that policymakers and public health practitioners could use to develop strategies to improve public health and address the climate crisis.

“As a millennial, I have always been concerned about mitigating human impacts on the environment,” said Bui. “A sustainable dietary pattern should not only be healthy but also consistent within planetary boundaries for greenhouse gas emissions and other environmental parameters.”

To create their Planetary Health Diet Index (PHDI), researchers reviewed existing research on the relationships between various food groups and health outcomes based on the EAT-Lancet reference diet that accounts for the environmental impacts of food production practices. They then applied the index to analyze outcomes among over 100,000 participants in two large cohort studies conducted in the United States. The data set included over 47,000 deaths during a follow-up period spanning over three decades from 1986-2018.

Overall, they found that people in the highest quintile (the top one-fifth of participants) for PHDI had a 25 per cent lower risk of death from any cause compared to those in the lowest quintile.

Bui cautioned that the PHDI does not necessarily reflect all food items and their relationships with all major diseases in all countries. People with specific health conditions, religious restrictions, or different food accessibility due to socioeconomic status or food availability may face challenges with adhering to a more sustainable diet pattern. Further research could help to elucidate and address such barriers.

“We hope that researchers can adapt this index to specific food cultures and validate how it is associated with chronic diseases and environmental impacts such as carbon footprint, water footprint, and land use in other populations,” said Bui.