Peanut Intake Enriches Butyrate Producing Bacteria and Expression of a Gene Associated With Butyrate Production in Adults With Elevated Fasting Glucose: An RCT

Abstract

ObjectivesTo assess the effect of consuming 28 g/d of peanuts for 6-weeks, compared to an isocaloric lower fat, higher carbohydrate (LFHC) snack, on gut microbiota composition in adults with elevated fasting glucose. Further, to identify functional and compositional differences in responders using metatranscriptomics. MethodsIn a randomized, crossover trial, 50 adults (52% male; 42 ± 15 y; BMI 28.3 ± 5.6 kg/m2; glucose 100 ± 8 mg/dL) consumed 28g/d of dry roasted, unsalted, peanuts (160 kcal) or a LFHC snack for 6-wk with a 4-wk washout period. Fecal samples were collected at the baseline and endpoint of each period. Gut microbiota composition was measured using 16 rRNA sequencing and QIIME2 for amplicon sequence variant assignment. Metatranscriptomic sequencing was conducted on baseline and endpoint samples from subjects with the greatest reduction in glucose following the peanut condition (n = 24), to measure gene expression related to microbial metabolic pathways. The NUGEN library preparation method was used to generate cDNA. MetaPhlan2 and HUMAnN2 were used for taxonomic and functional gene annotation, and iPATH3 and Pathview were used for mapping to functional gene pathways. ResultsNo between-condition difference in α or β microbiota diversity was observed. Following peanut intake, roseburia and ruminococcaceae were significantly enriched (LDA > 2; P < 0.05). Metatranscriptomics showed enrichment of the K03518 (aerobic carbon-monoxide dehydrogenase small subunit) gene following peanut intake (P < 0.05). ConclusionsEnrichment of roseburia was observed following consumption of 28 g/d of peanuts in adults with elevated fasting glucose. Metatranscriptomics revealed enrichment of the K03518 gene, which is associated with short chain fatty acid production and degradation of β-mannans. These results suggest peanut intake enriches a known butyrate producer and the increased expression of a gene implicated in butyrate production adds further support for peanut-induced gut microbiome modulation. Funding SourcesThe Peanut Institute and the National Center for Advancing Translational Sciences, National Institutes of Health (1UL1TR002014-01).