The modulatory effect of polyphenols from green tea, oolong tea and black tea on human intestinal microbiota in vitro.

In the present study, polyphenols from green tea (GTP), oolong tea (OTP) and black tea (BTP) were prepared by extraction with hot water and polyamide column chromatography. In antioxidant assay in vitro, each tea polyphenols exhibited potential activity; the intestinal absorption of GTP, OTP and BTP was investigated individually by Caco-2 transwell system, and each sample was poorly transported, illustrating a low transport rate for tea polyphenols through cell monolayers. The effects of GTP, OTP and BTP on human intestinal microbiota were also evaluated, and each sample induced the proliferation of certain beneficial bacteria and inhibited Bacteroides - Prevotella and Clostridium histolyticum . Moreover, the short-chain fatty acids (SCFA) produced in cultures with tea polyphenols were relatively higher. Together, these results suggested GTP, OTP and BTP may modulate the intestinal flora and generate SCFA, and contribute to the improvements of human health.