If you don’t want to do it for the planet, at least do it for yourself! Scientists at the Harvard HT Chan School of Public Health found that people in the United States who ate a more environmentally sustainable diet were 25% less likely to die over a 30-year period.
The new study builds on previous research that identified foods that benefit health and the environment, and foods that may harm both. The findings show how eating a more planet-friendly diet can help reduce the risk of death from a range of causes, including respiratory disease, heart disease and cancer.
The Planetary Health Diet is a concept coined by the EAT-Lancet Commission in a 2019 report. It’s a healthy, sustainable diet that focuses mainly on fruits, nuts, unsaturated oils, and non-starchy vegetables like tomatoes and broccoli. This contrasts with foods like red and processed meat and eggs, which have a greater impact on the environment — and often to your health.
To highlight these issues, the researchers propose a new metric.
“We proposed a new diet score that incorporates the best scientific evidence on the effects of diet on health and the environment,” study author Lin Bui of Harvard said in a media release. “The results confirmed our hypothesis that a higher Planetary Health diet score is associated with a lower risk of mortality.”
A healthy and sustainable diet
In 2019, the EAT-LanceT Commission developed the world’s first scientific goals for healthy and sustainable food systems, including the Planetary Health Diet – created to meet nutritional needs and promote health while staying within planetary boundaries. Adopting this would require doubling the average intake of fruits, vegetables, and nuts.
For their study, researchers surveyed 100,000 participants in the US. The data set includes 47,000 deaths over a 30-year follow-up period from 1986-2018. Overall, the findings, presented at the American Society for Nutrition conference, showed that participants with a good Planetary Health diet had a lower risk of death.
“As a millennial, I have always cared about mitigating human impacts on the environment,” Bui said in a media statement. “A sustainable diet must not only be healthy, but also sustainable within planetary boundaries for greenhouse gas emissions and other environmental parameters.”
Using the data collected, researchers created the Planetary Health Diet Index (PHDI) and ranked participants based on the healthiness and sustainability of their diets. They used this to assess the relationship between the scores and participants’ health outcomes. Those with the highest PhDI scores had a 25% lower risk of death compared to those with the lowest scores.
Researchers then looked a little closer to more specific causes of death. Those with high PhDI scores were associated with a 15% lower risk of death from cancer or cardiovascular disease, a 20% lower risk from neurogenerative diseases, and a 50% lower risk from respiratory diseases. Overall, eating a healthy and sustainable diet pays off.
Looking to the future, they hope their index can be used by policymakers and public health practitioners as a tool to improve human health while addressing climate change. However, they acknowledge that the PHDI does not take into account the challenges people may face in following a sustainable diet, such as the socioeconomic availability of food.