Effects of green tea on lipid metabolism in overweight or obese people: A meta-analysis of randomized controlled trials

Scope: The effects of green tea on lipid metabolism were inconsistent. The objective of this meta-analysis was to evaluate the effects of green tea on lipid metabolism in overweight or obese people. Methods and results: We searched randomized controlled trials (RCTs) comparing green tea with a control on lipid metabolism on PUBMED and WEB OF SCIENCE (January 1990 to September 2016), COCHRANE and EMBASE (updated to October 2016), and the Chinese databases CNKI, WanFang and CBMD. Twenty-one articles studying 1704 overweight or obese subjects were selected for this meta-analysis. The pooled results demonstrated that green tea significantly decreased plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL) levels in overweight or obese people. The weighted mean difference was -3.38mg/dl for TC (95% CI: -6.42, -0.33mg/dL) and -5.29mg/dL for LDL (95% CI: -7.92, -2.6 6mg/dL), respectively. Green tea intake, however, showed no effect on plasma triglyceride (TG) and high-density lipoprotein cholesterol(HDL) levels in overweight or obese people with a relatively high heterogeneity. Conclusion: The meta-analysis shows that drinking green tea can lower plasma TC and LDL levels significantly. Nevertheless, green tea's effect on plasma TG and HDL must be further evaluated by additional high-quality and large-scale RCTs.