Scientific Study

Background: Prior research has demonstrated that pistachio intake influences gut microbiota composition; however, there has been limited investigation of pistachio-related gut microbial modulation in populations with impaired glycemia. Objectives: The aim was to examine the effect of nighttime pistachio intake for 12 wk on the stool microbiota of adults with prediabetes [fasting plasma glucose (FPG) ≥100 mg/dL and ≤125 mg/dL]. Methods: A secondary analysis of data from a single-blind, 2-period, randomized crossover trial was conducted. Participants were provided with 57 g/d of dry roasted unsalted pistachios to consume as a nighttime snack or provided education to consume 1-2 carbohydrate (CHO; 15-30 g) exchanges (usual care) as a nighttime snack for 12 wk. Stool samples were collected at the beginning and the end of each condition and analyzed with 16S ribosomal ribonucleic acid gene sequencing. Taxonomic diversity was tested with linear mixed models (LMMs) and permutational analysis of variance of Bray-Curtis and weighted Unifrac dissimilarity indices. Taxonomic abundance by condition was tested using LMMs with Benjamini-Hochberg multiple testing correction. Results: The analytical sample included 51 participants (37% female, 49 ± 10 y, 31.5 ± 4 kg/m2, FPG 102 ± 10 mg/dL) who completed the trial (of 66 randomly assigned). β-diversity analysis showed community dissimilarity between the pistachio and usual care conditions postcondition (P = 0.001). Compared with the usual care condition, nighttime pistachio consumption modified several microbial taxa. Conclusions: In adults with prediabetes, intake of 57 g/d of pistachios as a nighttime snack altered stool microbial community diversity and composition compared with a CHO-rich snack, providing evidence of stool microbial effects with pistachio consumption.

https://doi.org/10.1016/j.cdnut.2025.107481