Influence of Tea Catechins on Lipid Metabolism

Tea catechins reduce serum cholesterol concentration and suppress postprandial hypertriacylglycerolemia in experimental animals and humans. These effects are mainly ascribed to gallate esters of catechins, (-)-epicatechin gallate (ECG) and (-)-epigallocatechin gallate (EGCG). During heat treatment for pasteurization, tea catechins are epimerized to so-called heat-treated tea catechins such as (-)-catechin gallate (CG) and (-)-gallocatechin gallate (GCG). We showed that both tea catechins and heat-treated tea catechins with galloyl moiety lower intestinal absorption of cholesterol by inhibiting micellar solubility of cholesterol. Since they inhibited pancreatic lipase in vitro and slowed down lymphatic absorption of triacylglycerol, we think that delayed intestinal absorption of triacylglycerol in the feeding of the catechin preparations causes suppression of postprandial hyper-triacylglycerolemia. It has been reported that tea catechins and heat-treated tea catechins with galloyl moiety suppress deposition of visceral fat in experimental animals and humans. Some studies suggested that stimulation of hepatic β-oxidation might be a cause of reduced deposition of visceral fat. However, our study did not show any acceleration of β-oxidation in rat liver. Although there are some controversial observations, results obtained suggest a possibility that tea catechins and heat-treated tea catechins with galloyl moiety improve lipid metabolism and contribute to prevention of life-style related diseases