Systematic review and meta-analysis of randomised, controlled trials on the effects of garlic supplementation on serum adiponectin and leptin levels

Abstract

BACKGROUND: Our aim in this meta-analysis was to determine the effect of garlic supplementation on adiponectin and leptin serum levels. METHOD: A systematic search was conducted using PubMed, Scopus, ISI Web of Science and Cochrane Library for eligible trials up to November 2020. A fixed-effects model was used to pool calculated effect sizes. RESULTS: Five trials were included in the overall analysis. Our analysis showed that garlic supplementation did not significantly affect adiponectin (Hedges's: 0.20; 95 CI: -0.06, 0.47; P-values = .12) and leptin (Hedges's: 0.08; 95 CI: -0.26, 0.41; P-values = .65) concentrations in comparison with placebo. However, in the subgroup analysis, significantly increased serum adiponectin level was seen following garlic supplementation in trials with a mean age of participants ˂30 years (Hedges's: 0.44; 95 CI: 0.01, 0.87; P-values = .04), the doses ˂1.5 g/d (Hedges's: 0.38; 95 CI: 0.02, 0.71; P-values = .04) and trials with duration ≥8 weeks (Hedges's: 0.48; 95 CI: 0.08, 0.89; P-values = .02). CONCLUSION: Overall, garlic supplementation could not change the circulatory adiponectin and leptin levels. Subgroup analyses showed a significant reduction in adiponectin levels in younger participants, longer duration and lower intervention dose. However, further studies are needed to confirm the present results.