A recent clinical study suggests that swapping late-night snacks for pistachios may support gut and metabolic health, particularly in adults with prediabetes.
The study, published in The American Journal of Clinical Nutrition, included about 50 adults with prediabetes. These individuals have blood sugar levels that are higher than normal but not yet in the diabetes range.
For 12 weeks, participants ate roughly two ounces of pistachios as their bedtime snack, which is about two small handfuls. In another 12-week phase, the same participants replaced the pistachios with a typical carb-based snack, such as crackers or toast.
Researchers analyzed stool samples taken before and after each phase to see how the two snack options influenced the gut microbiome.
After 12 weeks of nightly pistachio snacking, the participants’ gut microbiomes showed noticeable differences compared to when they ate carb-based snacks. The pistachio phase increased levels of beneficial bacteria like Roseburia and Lachnospiraceae. These bacteria are known for producing butyrate, a short-chain fatty acid that helps lower inflammation, strengthens the gut lining, and supports metabolic balance.
At the same time, bacteria linked to poorer metabolic health, toxin buildup, and gut barrier dysfunction, such as Flavonifractor and Eubacterium, decreased.
These microbial shifts suggest that pistachios may help create a gut environment that is more resilient and metabolically healthy, especially in people with blood sugar challenges. The researchers did not see major changes in fasting glucose or insulin resistance over 12 weeks, but the microbiome changes indicate that improvements could appear with longer-term habits.
Pistachios are rich in fiber, which feeds gut bacteria, as well as plant-based protein, healthy fats, and a blend of polyphenols and antioxidants that help reduce inflammation. Unlike many nighttime snacks that can spike blood sugar, pistachios have a low glycemic impact. This means they help stabilize energy and may prevent overnight glucose dips that can disrupt sleep.
The findings indicate that swapping a typical late-night snack for pistachios is a simple, evidence-based choice that could help gut bacteria thrive and support metabolic balance, particularly for those looking to manage healthy blood sugar levels.
