A Human and Animal Based Study Reveals That a Traditionally Fermented Rice Beverage Alters Gut Microbiota and Fecal Metabolites for Better Gut Health

Abstract

Fermented rice beverages are consumed globally, especially in Southeast Asia. In India, such beverages are consumed by a substantial population of ethnic communities. In this study, the gut bacterial diversity of rice beverage drinkers from Assam, India (n = 27) was compared with that of nondrinkers (n = 21) with the next-generation sequencing (NGS) of fecal metagenomic 16S rDNA, which indicated changes in 20 bacterial genera. Further, mice (n = 6, per treatment group) were gavaged daily for 30 days with different fractions of the beverage, which included rice beverage (RB), soluble (SF), and insoluble fractions (IF) to determine the effects of different components of the beverage. A comparison of gut bacteria at two time points, 0 and 30 days of treatments, suggested changes in 48 bacterial genera across the different treatment groups in mice. Major bacterial changes were suggestive of functional components associated with gut health, as observed in both humans and mice. Next, the Gas Chromatography–Mass Spectrometry (GC–MS) of mice stool after 30 days of treatments showed a total of 68 metabolites, of which hexadecanoic acid, a flavor component of this beverage, was present in the feces of all mouse treatment groups except controls. These metabolites showed treatmentwise clustering in groups in a partial least-squares discriminant analysis (PLS–DA) plot. Blood endotoxin levels were lower in all treatment groups in the mice compared to those of the controls. The findings of the study are suggestive of the gut modulatory effects of the beverage on the basis of the observed features of the bacterial changes.

Keywords

• fermented foods
• gut microbiota
• histology
• metabolites
• rice beverage
• next-generation sequencing