Impact of green tea on obesity-related hormones in postmenopausal women: A systematic review and meta-analysis of randomized controlled trials

Abstract

Objective: Menopause leads to hormonal changes that increase visceral fat, raising risks for metabolic disorders and breast cancer due to altered adipocytokine levels. Green tea (Camellia sinensis L.), containing catechins like EGCG (epigallocatechin gallate), may improve metabolic health in postmenopausal women. In this review we assessing the effects of green tea consumption on key obesity related hormones in postmenopausal women. Materials and Methods: This study reviewed randomized controlled trials (RCTs) from PubMed, Science Direct, Cochrane Library, and Google Scholar up to March 2024, focusing on green tea's effects on leptin, adiponectin, ghrelin, and insulin. Eight RCTs with 632 participants were analyzed using standardized mean differences (SMDs) with 95% confidence intervals (CIs) in a random-effects model. Heterogeneity was measured with the I2 statistic, and publication bias was assessed via Egger's test and funnel plots. Results: Green tea significantly reduced ghrelin levels (SMD: -4.63, 95% CI: -8.44 to -0.82, p = 0.02, I2 = 98.98%), particularly at doses >1000 mg/day and durations >8 weeks. No significant effects were observed for leptin (SMD: -0.33, 95% CI: -0.89 to 0.22, p = 0.24), adiponectin (SMD: -0.53, 95% CI: -1.44 to 0.39, p = 0.26), or insulin (SMD: -0.87, 95% CI: -4.31 to 2.58, p = 0.62). Subgroup analyses revealed significant reductions in leptin at doses >1000 mg/day, durations ≤8 weeks, and BMI <29 kg/m2; adiponectin at 400-1000 mg/day and insulin at durations ≤8 weeks and BMI <29 kg/m2. High heterogeneity and some evidence of publication bias were noted. Conclusion: Green tea notably reduced ghrelin, with context-specific effects on leptin, adiponectin, and insulin based on dose, duration, and body mass index (BMI), suggesting tailored benefits for postmenopausal women's metabolic health.