The effects of green tea extract supplementation on body composition, obesity-related hormones, and oxidative stress markers: A grade-assessed systematic review and dose-response meta-analysis of randomized controlled trials.

Research indicates that green tea extract (GTE) supplementation is beneficial for a range of conditions, including several forms of cancer, cardiovascular, and liver diseases; nevertheless, the existing evidence addressing its effects on body composition, oxidative stress, and obesity-related hormones is inconclusive. This systematic review and meta-analysis aimed to investigate the effects of GTE supplementation on body composition (body mass [BM], body fat percentage [BFP], fat mass [FM], body mass index [BMI], waist circumference [WC]), obesity-related hormones (leptin, adiponectin, and ghrelin) and oxidative stress (malondialdehyde [MDA], and total antioxidant capacity [TAC]) markers. We searched proper databases, including PubMed/Medline, Scopus, and Web of Science, up to July 2022 to recognize published randomized controlled trials (RCTs) that investigated the effects of GTE supplementation on the markers mentioned above. A random-effects model was used to carry out a meta-analysis. The heterogeneity among the studies was assessed using the I 2 index. Among the initial 11286 studies identified from an electronic database search, 59 studies involving 3802 participants were eligible to be included in this meta-analysis. Pooled effect sizes indicated that BM, BFP, BMI, and MDA significantly reduced following GTE supplementation. In addition, GTE supplementation increased adiponectin and TAC, with no effects on FM, leptin, and ghrelin. Certainty of evidence across outcomes ranged from low to high. Our results suggest that GTE supplementation can attenuate oxidative stress, BM, BMI, and BFP, which are thought to negatively affect human health. Moreover, GTE as a nutraceutical dietary supplement can increase TAC and adiponectin.