• Plant-based diets rich in whole grains, nuts, coffee, and veggies are linked to lower risk of diabetes.
• Nutrients called polyphenols help explain why some plant foods are so healthy, new research suggests.

There’s even more evidence that a plant-based diet has major health benefits, especially when it comes to a healthy metabolism and stable blood sugar.

A plant-based diet rich in specific nutrients called polyphenols may help stave off type 2 diabetes, according to a study published April 8 in Diabetologia, the journal of the European Association for the Study of Diabetes.

Researchers from the Harvard T.H. Chan School of Public Health looked at data from 10,684 participants, mostly white, middle-aged healthcare professionals. The data researchers focused on was metabolites, chemical compounds that are created as the human body breaks down the food for energy, which can vary based on the type of diet a person eats. By comparing metabolites and health outcomes during the study, researchers were able to see which eating habits were associated with lower risk of developing diabetes.

Specifically, people who ate a diet high in plant-based foods like whole grains, veggies, nuts, coffee, and legumes were less likely to be diagnosed with diabetes than their peers who ate more animal-based foods or processed foods.

The findings are supported by a wealth of previous evidence suggesting vegan and vegetarian diets are good for us, according to Dr. Frank Hu, senior author of the study and chair of the nutrition department at Harvard T.H. Chan School of Public Health.

“The results are not surprising given that the health benefits of healthy plant-based foods have been well-documented,” Hu told Insider.

Understanding the link between specific compounds and plant foods could help better inform which diets are healthiest for preventing certain illnesses like diabetes, he said.

Foods like grains, beans, veggies, nuts, and coffee are rich in beneficial nutrients called polyphenols

Not all plant-based diets in the study were equally beneficial. Diets high in more processed plant-based foods like refined grains, fruit juice, potatoes, and sweets weren’t linked to lower risk of diabetes, researchers found.

Based on data from metabolites, the findings suggest that specific nutrients in whole plant foods called polyphenols may account for the health benefits of certain plant-based diets.

Foods associated with the healthy plant-based diet in the study include whole grains, vegetables, nuts, and legumes, as well as coffee, all of which are rich sources of polyphenols.

Coffee, for instance, is high in trigonelline, a compound linked to better insulin sensitivity in some research. Another compound linked to consumption of coffee, as well as whole grains and fruit, is called hippurate, and it’s been linked to more stable blood sugar.

Eventually, closer study of metabolites like hippurate and trigonelline could help experts understand how different plant-based diets influence disease risk, and how certain diets may help prevent diabetes, according to Hu. For now, the evidence suggests your best bet for health is to eat plenty of unprocessed plants and cut back on processed foods and added sugars, even if they are technically plant-based.

“When adopting a plant-based diet, we recommend consumers to choose healthy plant foods, such as whole grains, fruits, vegetables, legumes, and nuts,” he said. “Limit the consumption of unhealthy plant foods, such as refined grains like white bread and pizza and high glycemic foods like sweets and sugar-sweetened beverages.”