Dietary saponins from four popular herbal tea exert prebiotic-like effects on gut microbiota in C57BL/6 mice

Herbal saponins have raised considerable interest for their health-promoting effects, but have not been examined for their role as prebiotics. This study aimed to investigate the impact of saponins on gut microbiota in mice. Saponins from four herbal tea were chosen, i.e. saponins of ginseng (GS), red ginseng (RGS), notoginseng (NGS), and Gynostemma pentaphyllum (GpS). PLS-DA plots of the faecal DNA fingerprints revealed that microbiota from the saponins-treated and untreated mice clustered separately. Real time qPCR showed that some known beneficial bacteria, Bacteroides, Lactobacillus and Bifidobacterium, were enhanced in the treatment groups. GpS and NGS significantly increased the Bacteroidetes/Firmicutes ratio. Additionally, Faecalibacterium prausnitzii, a bacterium associated with human intestinal health, was stimulated by GpS treatment in a time-dependent manner. This study, for the first time, demonstrated that the health-promoting effects of dietary saponins might be, in part, through the manipulation of the gut microbiota to the benefit of the host.