Modulation of Intestinal Cholesterol Absorption by Dietary Tea Polyphenols

Tea is a very popular beverage and mainly categorized as green, oolong, or black tea. The typical polyphenols in green and black teas are catechins and theaflavins. Observational studies have demonstrated that the consumption of green tea or green tea catechins decrease serum cholesterol concentration. The results of animal studies suggest that these polyphenols inhibit intestinal cholesterol absorption and thereby, reduce serum cholesterol concentrations. These polyphenols inhibit the micellar solubilization of cholesterol (Ikeda I, Imasato Y, Sasaki E, Nakayama M, Nagao H, Takeo T, et al. Tea catechins decrease micellar solubility and intestinal absorption of cholesterol in rats. Biochim Biophys Acta 1992;. 1127(2):141. -146; Ikeda I, Kobayashi M, Hamada T, Tsuda T, Goto H, Imaizumi K, et al. Heat-epimerized tea catechins rich in gallocatechin gallate and catechin gallate are more effective to inhibit cholesterol absorption than tea catechins rich in epigallocatechin gallate and epicatechin gallate. J Agric Food Chem 2003;. 51(25):7303. -7307; Ikeda I, Yamahira T, Kato M, Ishikawa A. Black-tea polyphenols decrease micellar solubility of cholesterol in vitro and intestinal absorption of cholesterol in rats. J Agric Food Chem 2010;. 58(15):8591. -8595). The limited solubility of cholesterol by these polyphenols may be a major cause of the inhibition of cholesterol absorption. However, there is no information on the effects of these polyphenols on cholesterol transporters in enterocytes. Detailed studies are necessary to clarify how these polyphenols inhibit cholesterol absorption in the intestinal lumen and enterocytes.