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

Iris Trefflich,Stefan Dietrich,Annett Braune,Cornelia Weikert,Klaus Abraham

doi:10.3390/nu13061808

Abstract

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 n = 36; omnivores n = 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 (p = 0.005) and ammonia concentration (p = 0.01) were significantly lower in vegans than in omnivores, while fiber intake was higher (p < 0.0001). Shannon diversity was higher in omnivores compared to vegans on species level (p = 0.04) only. In vegans, a cluster of Faecalibacterium prausnitzii, Prevotella copri, Dialister spp., and Eubacterium spp. was predictive for SCFA and BCFA concentrations. In omnivores, Bacteroides spp., Clostridium spp., Ruminococcus spp., and Prevotella copri 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.

Highlights

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The community of all living microorganisms across the human body is termed as the “microbiota”, with most microorganisms living in the gut system [1]
The study population was sex- and agematched. Lifestyle factors, such as physical activity or smoking, body mass index (BMI), and educational level did not differ significantly between vegans and omnivores, which may be attributed to the small study size

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The community of all living microorganisms across the human body is termed as the “microbiota”, with most microorganisms living in the gut system [1]. The intestinal microbiota, an ecosystem itself, consists mostly of bacteria alongside viruses, fungi, or protozoans with a commensal relationship with the host [2]. Analyses of stool samples of healthy subjects revealed a gene catalogue of approximately 3 million different microbial genes and more than 1000 different bacterial species [3]

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