Short- and Branched-Chain Fatty Acids as Fecal Markers for Microbiota Activity in Vegans and Omnivores

• Main Authors: Iris Trefflich, Stefan Dietrich, Annett Braune, Klaus Abraham, Cornelia Weikert
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Nutrients
• Subjects: vegan diet; short-chain fatty acids; branched-chain fatty acids; fecal pH; intestinal microbiota
• Online Access: https://www.mdpi.com/2072-6643/13/6/1808

A vegan diet could impact microbiota composition and bacterial metabolites like short-chain (SCFA) and branched-chain fatty acids (BCFA). The aim of this study was to compare the concentrations of SCFA, BCFA, ammonia, and fecal pH between vegans and omnivores. In this cross-sectional study (vegans <i>n</i> = 36; omnivores <i>n</i> = 36), microbiota composition, fecal SCFA, BCFA, and ammonia concentrations and pH were analyzed in complete stool samples. A random forest regression (RFR) was used to identify bacteria predicting SCFA/BCFA concentrations in vegans and omnivores. No significant differences in SCFA and BCFA concentrations were observed between vegans and omnivores. Fecal pH (<i>p</i> = 0.005) and ammonia concentration (<i>p</i> = 0.01) were significantly lower in vegans than in omnivores, while fiber intake was higher (<i>p</i> < 0.0001). Shannon diversity was higher in omnivores compared to vegans on species level (<i>p</i> = 0.04) only. In vegans, a cluster of <i>Faecalibacterium prausnitzii</i>, <i>Prevotella copri</i>, <i>Dialister</i> spp., and <i>Eubacterium</i> spp. was predictive for SCFA and BCFA concentrations. In omnivores, <i>Bacteroides</i> spp., <i>Clostridium</i> spp., <i>Ruminococcus</i> spp., and <i>Prevotella copri</i> were predictive. Though SCFA and BCFA did not differ between vegans and omnivores, the results of the RFR suggest that bacterial functionality may be adapted to varying nutrient availability in these diets.