Eating foods that promote good health — particularly nuts, fruits, vegetables and whole grains — benefits the environment, according to a study published in the Proceedings of the National Academy of Sciences (PNAS).
Eating foods that some experts believe are harmful to health — particularly processed and unprocessed red meat — damages the environment, the study also found.
The authors of the study, a team of researchers from the University of Minnesota and Oxford University, say their study offers the first comprehensive look at the effects of specific foods on both human health and the environment.
“This study shows that eating healthier also means eating more sustainably,” said David Tilman, the study’s senior author and a professor of ecology, evolution and behavior at the University of Minnesota, in a released statement.
“Normally, if a food product is good for one aspect of a person’s health, it’s better for the other health outcomes as well. The same holds for environmental outcomes,” he added.
For the study, Tilman and his colleagues explored the impact on human health and the environment of 15 foods commonly found in a Western diet: chicken, dairy, eggs, fish, fruits, legumes, nuts, olive oil, potatoes, processed red meat, refined grain cereals, sugar-sweetened beverages, unprocessed red meat, vegetables and whole-grain cereals.
Using data from previous research — 19 meta-analyses of the impact of different foods on health, as well as life-cycle analyses of the natural resources needed to grow those foods — the researchers calculated how eating one extra serving a day of each of the 15 foods to the average American diet would affect five different health outcomes (type 2 diabetes, stroke, heart disease, colorectal cancer and early death) and five aspects of environmental harm (the amount of water and land required, greenhouse gas emissions, and water and soil pollution).
They then looked to see how those two outcomes compared across all the foods.
They found that most foods linked to a lower risk of disease — primarily nuts, fruits, vegetables, legumes, whole grains and olive oil — had the lowest impact on the environment.
Similarly, most foods often linked to a higher risk of disease — primarily beef, pork and other unprocessed and processed red meat — were found to have the highest impact on the environment. In fact, the researchers estimated that the environmental impact of the production of a serving of unprocessed or processed red meat was 10 to 100 times larger than that of a serving of plant-source foods.
But not every food fit neatly into those patterns. Fish was one example. Although generally considered a healthful food, some methods of fish production (such as bottom-trawling fisheries) emit more greenhouse gases than other methods and thus have a moderate impact on the environment, the researchers explain.
On the other hand, sugar-sweetened beverages, which pose a significant risk to health, were found to have a relatively low environmental impact.
A call for change
To help reduce the devastating effects of climate change, the United Nations recommended earlier this year that populations around the world reduce their meat consumption and adopt plant-based diets.
By cutting back on meat, more land can be used to store the greenhouse gases emitted through human behaviors, the UN experts explained.
“It’s important that all of us think about the health impacts of the foods we eat,” said Jason Hill, one of the current study’s co-authors and a biosystems engineer at the University of Minnesota, in a released statement.
“We now know that making our nutrition a priority will pay dividends for the Earth, as well,” he added.
FMI: You’ll find the study on the PNAS website.