Green tea extract inhibits the lymphatic absorption of cholesterol and α-tocopherol in ovariectomized rats

Abstract

Evidence indicates that green tea consumption lowers the serum level of cholesterol (CH). This study was conducted to determine whether green tea lowers the intestinal absorption of CH and other lipids in ovariectomized (OX) rats. OX rats with lymph duct cannulae were infused at 3.0 mL/h for 8 h via an intraduodenal catheter with a lipid emulsion containing 14C-cholesterol (14C-CH) and α-tocopherol (αTP) without (GT0) or with green tea extract standardized to 42.9 mg (GT1) or 120.5 mg (GT2) of total catechins in PBS (pH 6.5). Green tea extracts dose-dependently reduced (P < 0.05) the lymphatic absorption of 14C-CH. The cumulative absorptions of 14C-CH in rats infused with GT0, GT1 and GT2 were 36.3 ± 1.1, 20.7 ± 4.3 and 4.8 ± 4.1% dose, respectively. The percentage distribution of esterified CH did not differ between rats infused with GT0 and GT1 (80.2 ± 2.3% vs. 79.0 ± 1.7%), but was significantly lower in those given GT2 (69.1 ± 6.8%). The absorption of αTP also was significantly reduced by GT1 (736.5 ± 204.9 nmol, 20.8 ± 5.8% dose) and GT2 (281.0 ± 190.8 nmol, 7.9 ± 5.4% dose) compared with GT0 (1048.8 ± 174.9 nmol, 29.6 ± 4.9% dose). The absorption of fat was significantly increased by GT1 (862.6 ± 151.1 μmol) but lowered by GT2 (557.9 ± 252.2 μmol) relative to GT0 (717.7 ± 39.1 μmol). The findings provide direct evidence that green tea has a profound inhibitory effect on the intestinal absorption of CH and αTP in OX rats. Whether the inhibitory effect of green tea extract is attributable to a specific catechin(s) and other components in green tea remains to be determined.