A recent clinical trial has examined how eating a specific nighttime snack affects the gut microbiome in adults with prediabetes.
The study, published in The American Journal of Clinical Nutrition, included about 50 adults with prediabetes, a condition where blood sugar levels are elevated but not yet in the diabetes range.
For 12 weeks, participants ate about two ounces of pistachios as their bedtime snack, roughly two small handfuls. In another 12-week phase, the same participants swapped the pistachios for 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, participants’ gut microbiomes looked noticeably different from when they had eaten carb-based snacks. The pistachio phase increased levels of beneficial bacteria like Roseburia and Lachnospiraceae, which are known for producing butyrate. Butyrate is a short-chain fatty acid that lowers 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. While researchers did not see major changes in fasting glucose or insulin resistance over 12 weeks, the microbiome changes hint that improvements could emerge with longer-term habits.
Pistachios are rich in fiber, plant-based protein, healthy fats, and a blend of polyphenols and antioxidants that help reduce inflammation. Unlike many nighttime snacks that spike blood sugar, pistachios have a low glycemic impact, meaning they help stabilize energy and prevent overnight glucose dips that can disrupt sleep.
Swapping a usual late-night snack for pistachios is a simple move that could help gut bacteria thrive and metabolism stay balanced, particularly for those looking to support healthy blood sugar levels.
