A new study led by Kristina Petersen associate professor of nutritional sciences at Penn State found that eating pistachios at night can influence gut bacteria in adults with prediabetes. While the full therapeutic impact is still uncertain Petersen noted the results could be meaningful for those aiming to improve metabolic health.

Published in Current Developments in Nutrition the study suggests that swapping a typical carbohydrate-rich bedtime snack with pistachios may alter the gut microbiome. Earlier research by the same team showed that pistachios have a comparable effect on blood glucose levels as consuming 15 to 30 grams of carbohydrates.

Terrence Riley lead author and postdoctoral fellow at LSU explained that people with prediabetes are often advised to eat 15–30 grams of carbohydrates at night  like one or two slices of whole grain bread to manage blood sugar.

Researchers found higher levels of beneficial bacteria such as Roseburia and members of the Lachnospiraceae family in the pistachio group. These bacteria are known to produce butyrate a short-chain fatty acid with several health benefits. Kristina Petersen noted that butyrate fuels colon cells supports gut barrier integrity and has anti-inflammatory effects. The results highlight pistachios' potential to positively influence metabolic health through the gut microbiome.

Pistachios appear to significantly alter the gut microbiome in adults with prediabetes particularly when eaten as a nighttime snack said Petersen. These changes may offer long-term health benefits potentially slowing the progression to Type 2 diabetes or reducing systemic inflammation areas we plan to study further.

Petersen noted that pistachio consumption led to a decrease in certain bacteria linked to poorer metabolic health. Levels of Blautia hydrogenotrophica associated with harmful compounds that can affect kidney and heart health were reduced. Similarly Eubacterium flavonifractor which breaks down helpful antioxidants from foods like pistachios also declined. 

Petersen highlighted the strength of the study’s design a randomized crossover clinical trial which allowed all participants to receive both the pistachio and standard care interventions in a randomized order. This approach provided a clearer understanding of how specific foods like pistachios can impact the gut microbiome.

Although the study showed noticeable changes in gut bacteria Petersen emphasized that it's still uncertain whether these microbial shifts directly lead to measurable health improvements a question future research will need to address.

Source: https://www.psu.edu/news/health-and-human-development/story/nighttime-pistachio-snacking-may-reshape-gut-microbiome