Fruits, Veggies, and Whole Grains Reduce Risk of Type 2 Diabetes by Almost 30%

Higher consumption of fruit, vegetables, and whole grain foods may help reduce your risk of developing type 2 diabetes, according to two studies published in the British Medical Journal on July 8. 

Diabetes affects approximately 10% of the U.S. population, and 1.5 million Americans are diagnosed with this condition every day. While previous research has suggested certain dietary patterns can reduce the risk of developing type 2 diabetes, these new studies corroborate this notion.

Fruits and Vegetables

The first study, which focused on fruits and vegetables, used plasma vitamin C and carotenoids (plant pigments) found in blood samples as indicators of fruit and vegetable intake. The researchers chose to use blood samples instead of the more traditional food frequency questionnaire to assess dietary intake to avoid measurement error and recall bias.

Because vitamin C and carotenoids are found in many fruits and vegetables, they serve an objective markers of fruit and vegetable intake. People who do not eat a diet rich in fruits and vegetables are likely not taking in as much vitamin C and carotenoids, and this would be reflected in their plasma levels.

After evaluating data from 9,754 participants with new-onset type 2 diabetes and 13,662 people without diabetes, researchers determined the higher the plasma levels of vitamin C and certain carotenoids, the lower the incidence of diabetes.

This data “suggest that diets rich in even modestly higher fruit and vegetable consumption could help to prevent development of type 2 diabetes," the study authors wrote. "It should be noted that these findings and other available evidence suggest that fruit and vegetable intake, rather than vitamin supplements, is potentially beneficial for the prevention of type 2 diabetes."

In other words, supplements are not a substitute for a poor diet. But dietitians know hitting the recommended 2 cups of fruit and 2.5 cups of veggies per day can be a challenge from whole foods alone.

“Many people are motivated to avoid type 2 diabetes and know they should be eating more fruits and vegetables, Casey Seiden, RD, CDE, a registered dietitian, tells Verywell. "But when they are currently eating one to two servings per day and are told the recommendation is to consume five, it can feel overwhelming and cause many well-intentioned individuals to abandon their efforts."

She explains that the newly-published data regarding fruits and vegetables is encouraging because it shows that even a slight increase of 66 grams per day—equivalent to about a 1/2 cup of chopped red bell pepper—can decrease the risk of type 2 diabetes by 25%.

Whole Grain

In the second study, researchers focused on the relationship between whole grain intake and type 2 diabetes risk. Whole grains are foods that are rich in fiber, antioxidants, and B-vitamins, and include foods like quinoa, popcorn, whole grain bread, and brown rice.

Using data from 158,259 women and 36,525 men who did not have type 2 diabetes, cardiovascular disease, or cancer when the study began, researchers evaluated the relationship between whole grain intake and type 2 diabetes incidence over the course of four years.

Participants who consumed the most whole grain (one or more servings per day) had a 29% lower rate of type 2 diabetes compared with those in the lowest intake group (less than one serving per month). Certain whole grains offered different rates of risk reduction. For example, whole grain cold breakfast cereal and dark bread don't offer much type 2 diabetes risk reduction after 0.5 servings a day. And while popcorn can offer a protective effect, it may actually increase type 2 diabetes risk if more than one serving is consumed per day.

Because associations did not vary significantly after controlling for physical activity, family history of diabetes, or smoking status, the authors concluded that higher consumption of whole grain is associated with a lower risk of type 2 diabetes. The specific foods that they mentioned include:

• Whole grain breakfast cereal
• Oatmeal
• Dark bread
• Brown rice
• Added bran
• Wheat germ

Why This Matters

The findings from both of these studies highlight how eating a generally healthy diet rich in fruits, vegetables, and whole grains can reduce the risk of developing type 2 diabetes.

"These studies confirm what we already know: that diet plays a critical role in preventing the risk of diabetes," Shahzadi Devje, RD, CDE, MSc, registered dietitian and owner of Desi~licious RD, tells Verywell. “In an era of keto-craze and clean eating, it's important to remind ourselves that healthy eating is not complicated for chronic disease prevention. Basic nourishing foods—whole grains, vegetables and fruits—are accessible across cultures and can be enjoyed daily.”