Potential Benefits of Green Tea in Preventing Breast Cancer
Researchers conducted a double-blind, randomized, placebo-controlled intervention study to investigate the effects of green tea on circulating hormone levels, an established breast cancer risk factor. The effect of the main green tea catechin, epigallocatechin gallate (EGCG), taken in a green tea extract, polyphenon E (PPE) was studied. Postmenopausal women (n = 103) were randomized into 3 arms: placebo, 400-mg EGCG as PPE, or 800-mg EGCG as PPE, for 2 months. Urinary tea catechin and serum estrogen, androgen, lipid, glucose-related markers, adiponectin, and growth factor levels were measured at baseline and at the end of months 1 and 2 of intervention. Low-density lipoprotein (LDL)-cholesterol decreased significantly in both PPE groups but was unchanged in the placebo group; the change in LDL-cholesterol differed between the placebo and PPE groups. Glucose and insulin levels decreased nonsignificantly in the PPE groups but increased in the placebo group; statistically signif icant differences in changes in glucose and insulin were found. Findings suggest that green tea (400- and 800-mg EGCG as PPE; ~5-10 cups) supplementation for 2 months may have beneficial effects on LDL-cholesterol concentrations and glucose-related markers.