Watan-A U.S. study has revealed that eating pistachios at night may positively influence the composition of gut bacteria in adults with prediabetes—an effect that could benefit metabolic health and help slow the progression to type 2 diabetes.
Researchers from Penn State University highlighted pistachios as a smart alternative to carbohydrate-based nighttime snacks for people with prediabetes, while maintaining a similar impact on blood glucose regulation. The findings were published Monday in Current Developments in Nutrition.
What is Prediabetes?
Prediabetes is a condition where blood sugar levels are higher than normal but not high enough to be classified as type 2 diabetes. It’s considered a “warning stage,” indicating an increased risk of diabetes and heart disease unless lifestyle changes are made—such as improving diet, increasing physical activity, and losing weight.
Roughly one-third of the U.S. population has prediabetes, with most at risk of developing type 2 diabetes. Yet, effective early nutritional interventions remain limited. Although pistachios have been shown to improve overall diet quality, their effect on the gut microbiome—an essential factor in glucose regulation and inflammation—had not been fully understood.
The Study Design
The clinical trial involved 51 adults with prediabetes, conducted over two 12-week periods, with a washout phase in between to avoid result overlap. All participants followed both dietary protocols:
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First diet: A traditional nighttime snack containing 15–30 grams of carbohydrates (e.g., one or two slices of whole grain bread).
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Second diet: 56 grams of pistachios eaten at night instead of the carbohydrate snack.
Fecal samples were collected from participants and analyzed using advanced microbiome profiling techniques.
Eating pistachios at night led to an increase in beneficial gut bacteria—especially those that produce butyrate, a short-chain fatty acid that serves as a vital energy source for colon cells, supports gut barrier integrity, enhances immune function, and reduces chronic inflammation.
Conversely, there was a reduction in potentially harmful bacteria that produce compounds negatively affecting heart and kidney health, and in bacteria that break down antioxidant-rich plant foods.
These microbial shifts suggest pistachio consumption fosters a more balanced and gut-friendly microbiome environment, the researchers said.
The findings underscore pistachios as more than just nutrient-dense nuts—they hold the potential to reshape gut microbiota in ways that may significantly benefit metabolic health. This is especially important considering the strong link between gut bacteria and conditions like diabetes, obesity, and inflammation.
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