Green Tea Extract Supplementation Modifies Circulating Lipids in Postmenopausal Women: A Randomized, Placebo‐Controlled Clinical Trial

Abstract

BackgroundGreen tea has been suggested to improve cardiovascular risk factors including circulating lipid parameters predominantly based on small and short randomized controlled trials. Data from long‐term intervention studies with relatively large sample size are lacking.ObjectiveTo determine the effects of daily green tea extract (GTE) supplementation high in epigallocatechin gallate (EGCG) for 12 months on blood lipids in healthy postmenopausal women in U.S.Methods and designThis was an ancillary study carried out as part of a phase II randomized, double‐blind, placebo‐controlled trial to investigate the effects of GTE supplementation containing 843 mg EGCG on breast cancer risk biomarkers. Subjects were randomized to either the GTE (n= 538) or placebo (n= 537) group, and 936 women completed the one‐year intervention. Participants were healthy postmenopausal women (mean age of 59.8 ± 5.0 years), mainly non‐Hispanic white (97%), who did not regularly consume tea (<1 cup/week) or currently smoked cigarettes (31% former smokers), and had mean body mass index (BMI) of 25.1 ± 3.7 kg/m2. Each woman took 2 capsules of GTE or placebo twice daily for one year. Total cholesterol (TC), high‐density lipoprotein cholesterol (HDL‐C) and triglycerides (TG) were measured using spectrophotometry in fasting serum samples at baseline, month 6 and month 12. Levels of low‐density lipoprotein cholesterol (LDL‐C), non‐HDL cholesterol and the ratio of TC to HDL‐C were calculated. Participants provided information on demographic characteristics, lifestyle factors, and diet history at baseline. The repeated measures ANCOVA adjusted for age and BMI at baseline was used for calculating the mean change of circulating lipids for placebo and GTE treatment groups and testing for the differences between two groups.ResultsOne‐year supplementation with GTE capsules resulted in significant reduction of circulating TC (by 2.1%), LDL‐C (by 4.1%) and non‐HDL‐C (by 3.1%) (all Ps <0.001). The maximum reductions were observed in month 6. There was no change in HDL‐C concentration, but TG levels increased by 3.6% in GTE group compared with placebo group (P = 0.01). A significant reduction in TC was only observed among women with high (i.e. ≥200 mg/dL) baseline TC levels (P for interaction= 0.01), and those who did not use the cholesterol‐lowering drug statin. The effect of GTE on the increase in TG was confined to obese women (P for interaction = 0.06), and those with low baseline TG (i.e. <150 mg/dL).ConclusionsAmong healthy postmenopausal women, supplementation with GTE significantly reduced circulating TC and LDL‐C levels, especially in those with elevated baseline TC levels without use of lipid lowering drug statin. These novel findings suggest that GTE can be developed as a potential cholesterol lowering agent, especially for those who are intolerant to statin.Support or Funding InformationThis work was funded by the National Institute of Health (R01 CA127236) and the Department of Defense (W81XWH‐11‐1‐0013).