Dietitians recommend a light carbohydrate snack to prediabetics before bed, but new research shows pistachios may be a better option. Scientists at Penn State University found snacking on pistachios before bedtime positively impacts gut health and improves metabolic health for those with prediabetes.

Prediabetes is an elevated blood sugar condition that can lead to type 2 diabetes unless dietary changes are made. It is estimated as much as a third of the adults in the country have prediabetes and most will eventually have diabetes.

The change in gut microbiome composition is important because it can affect glucose regulation and inflammation.

"A common dietary recommendation for individuals with prediabetes is to consume a nighttime snack consisting of 15 to 30 grams of carbohydrates to help regulate overnight and morning blood glucose levels," said researcher Terrence Riley. "As an example, you could eat one or two slices of whole grain bread."

Through other research Penn State it was determined that snacking on a handful of pistachios was equivalent to between 15 and 30 grams of carbohydrates in terms of blood sugar impact.

Scientists in the study found two ounces of pistachios each night for 12 weeks resulted in significantly different microbial profile in stool samples compared to those who consumed the recommended 15-30 grams of a carbohydrate snack. The biggest changes were seen in the Roseburia bacterial group, as well as members of the Lachnospiraceae family. They were found in more abundance in the pistachio snacking group.

Those are considered to be "good" bacteria as they are known to produce beneficial short-chain fatty acids like butyrate, which is a primary energy source for colon cells and helps maintain a healthy gut barrier. It also helps support anti-inflammatory processes.

"Pistachios seem to be able to meaningfully shift the gut microbial landscape in adults with prediabetes especially when consumed as a nighttime snack," Petersen said. "These microbiome changes may offer other long-term health benefits—potentially helping to slow the development of Type 2 diabetes or to reduce systemic inflammation—which we hope to explore in future research."

The study consisted of 51 people with prediabetes. They participated in what is called a randomized crossover clinical trial, which is considered one of the best forms since all participants receive both treatments in a randomized order.

Click here to read more in the journal Current Developments in Nutrition.