The interaction effect and mechanism between tea polyphenols and intestinal microbiota: Role in human health

Tea polyphenols (TP) have shown various biological activities. However, for the low bioavailability, only small parts of TP are directly absorbed by the small intestine, the majority are thought to remain in the intestinal tract. The unabsorbed parts are metabolized to a variety of derivative products of different structures by intestinal flora, which may accumulate to exert physiological effects. Meanwhile, recent studies have demonstrated that TP may modulate intestinal bacterial diversity and richness, contributing to the improvements of host health. In this review, current information about the microbial degradation metabolites obtained from TP and their formation pathways were assembled. Additionally, in order to understand the two-way phenolic-microbiota interaction, the modulation of gut microbiota by TP was also discussed. In particular, the health benefits of TP may be attributed to their bioactive metabolites and the modulatory effect of human intestinal microbiota. Practical applications The human gut has been viewed as a bioreactor, which is the main place for the interaction of TP and gut microbiota. TP and their bacterial metabolites may accumulate to exert significant effects on intestinal microenvironment by modulating intestinal bacterial in addition to their direct beneficial effect. The health effects of TP between different people have been shown as the result of individual variability in intestinal microbial ecology. Furthermore, a better understanding of TP and intestinal microbiota will allow us to better evaluate the contribution of the microbial metabolites of TP to the improvements of host health.