Effects of green tea catechin extract on serum lipids in postmenopausal women: a randomized, placebo-controlled clinical trial.

The American journal of clinical nutrition

Nov 2016

DOI: 10.3945/AJCN.116.137075

Citations:98

Influential Citations:3

Interventional (Human) Studies

Enhanced Details

Methods

Design: Double-blind, randomized, placebo-controlled, parallel-arm trial; ancillary substudy of the Minnesota Green Tea Trial. Participants: postmenopausal women aged 50–70 with dense breast tissue at high risk for breast cancer; COMT genotype stratified; Randomized to GTE (n=463) or placebo (n=473); 936 completed the substudy; lipid panels measured at baseline, 6 and 12 months; intention-to-treat analysis.

Intervention

Green Tea Extract Catechin Complex (GTE); approximately 1315 mg catechins per day (including 843 mg EGCG); decaffeinated capsules; 4 capsules daily (2 in the morning after breakfast and 2 in the evening after dinner); duration: 12 months.

Results

One-year GTE supplementation significantly reduced total cholesterol, LDL cholesterol, and non-HDL cholesterol versus placebo; HDL cholesterol unchanged; triglycerides increased modestly in the GTE group. Reductions were greatest among participants with baseline total cholesterol ≥200 mg/dL; triglyceride increases were greater among obese participants and statin users. No significant interaction with COMT genotype; GTE did not enhance statin lipid effects. Per-protocol results were consistent with ITT findings. Conclusion: high-dose GTE lowers TC and LDL-cholesterol, particularly in those with elevated baseline TC, suggesting potential for cholesterol management in this population.

Limitations

Population predominantly non-Hispanic white and educated; lipid measurements based on a single baseline and endpoint; long-term storage of serum samples (1–3 years) may affect results; underpowered to detect COMT genotype interactions; relatively few statin users; generalizability limited to postmenopausal women at high breast cancer risk.

Abstract

BACKGROUND Green tea has been suggested to improve cardiovascular disease risk factors, including circulating lipid variables. However, current evidence is predominantly based on small, short-term randomized controlled trials conducted in diverse populations. OBJECTIVE The aim of this study was to examine the efficacy and impact of green tea extract (GTE) supplementation high in epigallocatechin gallate (EGCG) on blood lipids in healthy postmenopausal women. DESIGN This was an ancillary study of a double-blind, randomized, placebo-controlled, parallel-arm trial investigating the effects of a GTE supplement containing 1315 mg catechins (843 mg EGCG) on biomarkers of breast cancer risk. Participants were randomly assigned to receive GTE (n = 538) or placebo (n = 537) and were stratified by catechol-O-methyltransferase (COMT) genotype activity (high COMT compared with low or intermediate COMT genotype activity). They consumed either 4 GTE or identical placebo capsules daily for 12 mo. A total of 936 women completed this substudy. Circulating lipid panels including total cholesterol (TC), HDL cholesterol, and triglycerides were measured at baseline and at months 6 and 12. RESULTS Compared with placebo, 1-y supplementation with GTE capsules resulted in a significant reduction in circulating TC (-2.1% compared with 0.7%; P = 0.0004), LDL cholesterol (-4.1% compared with 0.9%; P < 0.0001) and non-HDL cholesterol (-3.1% compared with 0.4%; P = 0.0032). There was no change in HDL-cholesterol concentration, but triglyceride concentrations increased by 3.6% in the GTE group, whereas they decreased by 2.5% in the placebo group (P = 0.046). A significant reduction in TC was observed only among women with high (i.e., ≥200 mg/dL) baseline TC concentrations (P-interaction = 0.01) who consumed GTE capsules. The effect of GTE on the increase in triglycerides was mainly observed among obese women and statin users (P-interaction = 0.06). CONCLUSION Supplementation with GTE significantly reduced circulating TC and LDL-cholesterol concentrations, especially in those with elevated baseline TC concentrations. This trial was registered at clinicaltrials.gov as NCT00917735. show less