A meta-analysis of the effects of green tea combined with physical activity on blood lipids in humans

Introduction: Most studies of green tea extract (GTE) combined with physical activity have reported a preven-tative effect for cardiovascular disease; however, the findings regarding the effects on serum lipids are controversial. Objective: This meta-analysis aimed to examine the evidence of the effects of GTE combined with physical activity on the serum lipid content in humans. Methods: In June 2017, we conducted electronic searches of PubMed, Web of Science, and Cochrane Library to identify pertinent studies: those with an experiment period exceeding two weeks, human randomized controlled trials (RCTs), and those that only assessed GTE with physical activity were included. A random effects model meta-analysis was used in this review. Results: A total of 271 citations were retrieved in our search of the electronic literature, and 7 RCTs, which included 608 individuals, were identified. Overall, there was no significant decrease in low-density lipoprotein cholesterol (LDL-C) (SMD:-0.169; 95% confidence interval [CI]:-0.414 to 0.076; I²=22.7%; p=0.177) or total cholesterol (TC) levels between the GTE and placebo combined with the physical activity group. Similar results were also observed for high density-lipoprotein cholesterol (HDL-C) and triglycerides (TG). In the subgroup and sensitivity analyses of the five studies, the TC levels of the subjects who received a lower dose of epigallocatechin gallate (EGCG) together with performing physical activity were significantly decreased. Conclusion: Current evidence suggests that green tea combined with physical activity does not improve the lipid and lipoprotein levels in humans. Level of evidence I; Systematic review.