About one in three people in the United States has prediabetes, and most of them are at risk of developing Type 2 diabetes.
While doctors often recommend lifestyle changes, there are still not many proven food-based strategies to help prevent the disease.
Now, researchers at Penn State have found that eating pistachios at night might improve gut health in people with prediabetes, which could be important for managing blood sugar and reducing inflammation.
The study, led by Kristina Petersen, an associate professor of nutritional sciences, looked at how pistachios affect the gut microbiome—the community of bacteria living in the digestive system.
These bacteria play a key role in how the body handles sugar and inflammation, two factors tied to diabetes. The findings were published in the journal Current Developments in Nutrition.
The researchers asked 51 adults with prediabetes to eat a nighttime snack every day for 12 weeks. Some ate a typical carbohydrate-based snack like whole grain bread, while others ate about two ounces of pistachios.
After a break, they switched groups, so everyone tried both snacks. Stool samples were collected and tested to analyze changes in gut bacteria.
The results showed that eating pistachios led to noticeable changes in the gut microbiome. Bacteria that are known to be good for health, such as Roseburia and members of the Lachnospiraceae family, became more common. These bacteria produce a substance called butyrate, which helps support gut health and reduce inflammation in the body.
Dr. Petersen explained that butyrate is important because it gives energy to colon cells, strengthens the gut barrier, and helps control inflammation. This suggests that eating pistachios at night could be a simple way to support better metabolic health.
The study also found that some less helpful bacteria, like Blautia hydrogenotrophica and Eubacterium flavonifractor, decreased after pistachio consumption. These bacteria are linked to poorer health outcomes, so their reduction could be another positive effect of eating pistachios.
Lead author Terrence Riley, a former Penn State doctoral student and current postdoctoral researcher at Louisiana State University, said that people with prediabetes are often told to eat 15 to 30 grams of carbohydrates at night to help with blood sugar.
This study shows that pistachios, which offer the same effect on blood glucose, could be a better option because they also support gut health.
The study was carefully designed using a randomized crossover method, meaning all participants tried both the pistachio and carb-based snacks in different orders. This design helps rule out other factors and strengthens the findings.
While these early results are promising, the researchers say more studies are needed to find out whether the changes in gut bacteria lead to better long-term health outcomes. They hope future research will explore whether pistachios can help slow or prevent the development of Type 2 diabetes.
The study received funding from the American Pistachio Growers and several research organizations, including the National Institutes of Health and the U.S. National Science Foundation.
If you care about gut health, please read studies about how probiotics can protect gut health ,and Mycoprotein in diet may reduce risk of bowel cancer and improve gut health.
For more health information, please see recent studies about how food additives could affect gut health, and the best foods for gut health.
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