Traditional rice beer depletes butyric acid-producing gut bacteria and along with fecal butyrate levels in the ethnic groups of Northeast India.

Ethnicity, geography, and dietary habits are known to have dominant roles in modulating the gut microbiota. Two major ethnic groups and in the north-east of India consume traditionally prepared rice beer which contains various microbes and substances that promote the growth of such microbes, known as prebiotics. This study aimed to understand the effect of traditionally prepared rice beer on gut microbiota. A total of 134 (67 from each group) volunteers including non-drinkers and drinkers from three locations were recruited. Fecal and blood samples were collected to study fecal bacterial and metabolite profiles and biochemical markers, respectively. Amplicon 16S rRNA gene sequencing (region V3-V4) by next-generation sequencing showed similar alpha and beta diversities in both the ethnic groups. However, with rice beer consumption the abundance of Firmicutes, Bacteroidetes, Fusobacteria phyla was higher in the drinkers ( < 0.05) of whereas only Firmicutes were higher in ethnic group. At the genus level, the bacterial abundance of and were lower in the drinkers ( < 0.05) of both communities. Gas chromatography-mass spectrometry for the detection of fecal metabolites also revealed lower butyric acid in the feces of drinkers ( < 0.05). This study showed the effects of traditionally prepared rice beer on human gut microbiota and fecal metabolites. Further research is required to understand their effect on health.