Effect of 2-month controlled green tea intervention on lipoprotein cholesterol, glucose, and hormone levels in healthy postmenopausal women

Abstract

There have been no controlled intervention studies to investigate the effects of green tea on circulating hormone levels, an established breast cancer risk factor. We conducted a double-blind, randomized, placebo-controlled intervention study to investigate the effect of the main green tea catechin, epigallocatechin gallate (EGCG), taken in a green tea extract, polyphenon E (PPE). Postmenopausal women (n = 103) were randomized into three arms: placebo, 400-mg EGCG as PPE, or 800-mg EGCG as PPE as capsules per day 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. On the basis of urinary tea catechin concentrations, compliance was excellent. Supplementation with PPE did not produce consistent patterns of changes in estradiol (E2), estrone (E1), or testosterone (T) levels. 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 (P = 0.02). Glucose and insulin levels decreased nonsignificantly in the PPE groups but increased in the placebo group; statistically significant differences in changes in glucose (P = 0.008) and insulin (P = 0.01) were found. In summary, green tea (400- and 800-mg EGCG as PPE; ∼5-10 cups) supplementation for 2 months had suggestive beneficial effects on LDL-cholesterol concentrations and glucose-related markers.