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One Major Effect of Eating Blueberries, New Study Says

They may help your body manage glucose levels.
FACT CHECKED BY Cheyenne Buckingham

There are so many reasons to incorporate blueberries into your diet. Not only are they delicious, but they're also healthy for both your heart and brain health. Now, an increasing body of research is looking at how blueberries may even help manage your blood sugar.

After you eat a meal or snack, your digestive system breaks carbohydrates down into sugar (glucose), and a hormone called insulin works to regulate the glucose in your blood. "Insulin allows for glucose to enter into cells where it can be utilized for energy," explains Dr. Deena Adimoolam, MD, an endocrinologist, and member of our medical review board.

In a healthy person, blood glucose levels usually rise right after eating. Then, insulin starts working and glucose levels typically go back down to normal two hours after eating. Type 2 diabetes occurs when your body isn't able to use insulin properly or can't make enough of it.

"People with type 2 diabetes struggle with insulin resistance," says Dr. Adimoolam. "What this means is that people with type 2 diabetes make insulin, but their body is resistant to the effects of insulin which leads to high blood glucose levels."

A new study published in the journal Nutrients found that eating blueberries may help your body manage blood sugar in a few different ways.

In the study, researchers collected participants' blood samples shortly after they'd eaten fresh blueberries with a slice of white bread. These participants also ate 150 grams (5.3oz) of blueberries a day for six days and their blood samples were taken on the seventh day, directly after they ate a slice of bread without blueberries. A control group's blood samples were also taken.

Just 15 minutes after eating, the participants who ate blueberries with their slice of white bread had lower glucose spikes than the control group. This indicates that eating blueberries can help your body manage glucose levels after you eat simple carbohydrates, like white bread. Researchers think this might be because of specific processes that occur in your digestive tract after you eat blueberries.

They also found that those who'd eaten blueberries for six days didn't have significant differences in glucose levels from the control group. However, the participants who'd eaten blueberries for the previous six days did have lower insulin levels two hours after eating the bread than the control group. These results suggest that eating blueberries daily improves your body's sensitivity to insulin. The study's authors suggest that this is because blueberries have antioxidant and anti-inflammatory effects.

It's important to note that the subjects of the study were all sedentary, which means they performed little to no exercise. "Exercise makes your muscles more sensitive to insulin which leads to a possible improvement in blood glucose values," says Dr. Adimoolam.

This new research follows a study from last year, which specifically looked at blueberry consumption in men with type 2 diabetes, and found that eating freeze-dried blueberries improved health parameters like their glucose and insulin management, blood pressure, and even cholesterol.

Blueberries contain polyphenols, which are micronutrients, and specific polyphenols called anthocyanins, which are speculated to reduce inflammation. "Some believe that there may be a component of inflammation in type 2 diabetes leading to worsening insulin resistance," says Dr. Adimoolam. "Anthocyanins may improve inflammation in type 2 diabetes which could theoretically improve blood glucose values. However, we do not have extensive data to support this finding."

If you have type 2 diabetes, there may actually be a downside to eating blueberries, though. While anthocyanins may play some role in helping your body manage blood glucose, "fruits like blueberries have fructose, which also has the opposite effect and raise your blood sugar levels," says Dr. Adimoolam.

"The best treatment for type 2 diabetes in [the] majority of cases is lifestyle changes (such as diet, exercise, stress reduction, and sleep) and use of medications if needed," explains Dr. Adimoolam.

For more, be sure to check out 4 Biggest Food Studies About Diabetes You Should Know.

Urvija Banerji
Urvija Banerji has written about food for publications like Atlas Obscura, Eater, and The Swaddle. Read more
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