Association of dietary type with fecal microbiota and short chain fatty acids in vegans and omnivores

Abstract

Diet plays an essential role in modulating the bacterial composition within the gut. Data on the effect of vegan diets on the faecal microbiota and the production of short chain fatty acids are few. The present study compared the faecal microbiota of vegans and omnivores in Germany. Faecal samples were obtained from ten vegan and ten omnivore subjects with a similar social background. Macronutrient intake and anthropometric data were collected. The faecal microbiota of interest was quantified by real-time PCR with SYBR green using primers for the main bacterial phyla and genera. In addition, the production of the short chain fatty acids acetate, propionate, butyrate, valerate and the branched chain fatty acids iso-valerate and iso-butyrate were measured by gas chromatography. The faecal microbiota of the vegan group was enriched for the phyla Verrucomicrobia while it was diminished for the phylum Proteobacteria and lactic acid bacteria. The relative faecal concentrations of short-chain fatty acids did not differ between the groups. However, in the vegan group a lower amount of brain-chain fatty-acids, acetate and propionate, could be observed. Maintaining a vegan diet results in a shift in the microbiota and the production of short chain fatty acids. It remains to be determined how these shifts affect the host metabolism and disease risk.