About one in three people in the US has prediabetes, and most of them are at risk of developing type 2 diabetes.

Although doctors often recommend lifestyle changes, there are still not many proven dietary strategies for preventing the disease.

Researchers in Pennsylvania have found that eating pistachios at night may improve gut health in people with prediabetes, which may be important for managing blood sugar and reducing inflammation.

The study, led by Christina Petersen, associate professor of nutritional sciences, examined 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 associated with diabetes. The results were published in the journal Current Developments in Nutrition.

The researchers asked 51 adults with prediabetes to eat one nighttime snack every day for 12 weeks. Some of them consumed a typical carbohydrate-based snack such as whole grain bread, while others consumed about 56 grams of pistachios.

After a break, the groups switched so that everyone tried both snacks. Stool samples were taken and examined to analyze changes in gut bacteria.

The results show that eating pistachios leads to noticeable changes in the gut microbiome. Bacteria known to be beneficial to health, such as Roseburia and members of the Lachnospiraceae family, are more common. These bacteria produce a substance called butyrate, which supports gut health and reduces inflammation in the body.

Dr. Petersen explained that butyrate is important because it provides energy to colon cells, strengthens the intestinal barrier, and helps control inflammation. This suggests that eating pistachios at night may be a simple way to maintain better metabolic health.

The study also found that some less beneficial bacteria, such as Blautia hydrogenotrophica and Eubacterium flavonifractor, decreased after pistachio consumption. These bacteria are associated with poorer health outcomes, so reducing them may be another positive effect of pistachio consumption.

Lead author Terence Riley, a former doctoral student at the University of Pennsylvania and current postdoctoral fellow at Louisiana State University, said that people with prediabetes are often told to eat 15 to 30 grams of carbohydrates in the evening to help with blood sugar.

This study shows that pistachios, which have the same effect on blood glucose, may be a better option because they also support gut health.

The study was carefully planned using a crossover method, which means that all participants tried both pistachios and carbohydrate-based snacks in different sequences. This design helps to rule out other factors and strengthens the results. | BGNES