The Effect of Garlic (Allium sativum L) Supplementation on Circulating Adiponectin: a Systematic Review and Meta-Analysis of Randomized Controlled Trials

Our aim was to conduct a systematic review and meta-analysis on randomized controlled trials (RCTs) evaluating the effect of garlic on serum adiponectin levels. We searched Scopus, Web of Science, PubMed, and Cochrane Library to databases up to January 2021. RCTs investigating the effects of garlic on serum adiponectin levels in adult participants were included. The change in serum adiponectin levels was estimated using weighted mean differences (WMD) and standard deviations (SD). The random effects model was used to provide a summary of mean estimates and their SDs. Out of 386 records, 6 trials with 8 arms treatment which enrolled 266 subjects were included. Garlic supplementation resulted in a non-significant increase in adiponectin concentrations when compared to placebo, according to the pooled data (WMD, 0.27 Hedges' g; 95% confidence interval [CI], −0.07, 0.62; p = 0.124). Greater effects on adiponectin were observed in trials with supplementation dose less than 1.5 gram per day (WMD, 0.71 Hedges' g; 95% CI, −0.01, 1.43; p = 0.600) and in trials with female subset (WMD, 0.62 Hedges' g; 95% CI, −0.96, 2.21; p = 0.441). Garlic boosts adiponectin levels in general. However, due to different target population, various units for reporting adiponectin level and few eligible studies in final analysis, more research is needed to get a firm conclusion about the influence of garlic on adiponectin levels.