Abstract
ABSTRACT Introduction: Most studies of green tea extract (GTE) combined with physical activity have reported a preventative 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.
Highlights
Most studies of green tea extract (GTE) combined with physical activity have reported a preventative effect for cardiovascular disease; the findings regarding the effects on serum lipids are controversial
Three electronic databases(PubMed, Web of Science, and the Cochrane Library) were searched for articles written in English and published before June 2017, using the following combinations of text and medical subjects heading[MeSH] terms:“green tea extract” or“catechin”or“tea polyphenols”or“epigallocatechin gallate (EGCG)”or“Camelliasinesis”and“physical activity”or“exercise”or“walking”or“training”or“strength training”or“aerobic exercise”or“isometric exercises”; and“serum lipids”(“lipoproteins”or“high density lipoprotein cholesterol”or“high density-lipoprotein cholesterol (HDL-C)”or“low density lipoprotein cholesterol”or“low-density lipoprotein cholesterol (LDL-C) ”or“total cholesterol”or“TC”or“triglyceride”or“TG”)
We included randomized controlled trials (RCTs) investigating the effect of physical activity combined with GTE on the lipid profiles parameters (HDL-C, LDL-C, TG, and TC) in participants of both sexes
Summary
Most studies of green tea extract (GTE) combined with physical activity have reported a preventative effect for cardiovascular disease; the findings regarding the effects on serum lipids are controversial. One of the main mechanisms is the antioxidant effects, which prevent oxidative modification to LDL-C, which is an important step in the progression of atherosclerosis.[7] A meta-analysis reported that the intake of GTE improved the lipid profile in humans, especially for LDL-C and TC.[8] Cardiovascular disease (CVD) alone accounts for 48% of Non-communicable diseases, which leading cause of death worldwide, and is expected to affect more than 23.6 million people by 2030.9 CVD harms individuals and places a heavy economic burden on governments around the world.[10] The major risk factors for CVD include smoking, overall alcohol consumption, dietary cholesterol, hypertension, and diabetes mellitus.[11] controlling the risk factors for CVD is important for reducing its incidence. Lower levels of HDL-C, and higher levels of TC and TG have been associated with an increased risk of CVD.[12]
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