Effects of garlic supplementation and its derivatives on body weight and composition in adults: an updated systematic review and meta-analysis

Purpose Garlic supplementation may be inversely contributed to body weight and composition; however, previous results have been inconsistent. This study aims to evaluate the effect of garlic supplementation on body weight and composition using a systematic review and meta-analysis. Design/methodology/approach Online databases of PubMed, ISI Web of Science, Scopus and Google Scholar were searched up to January 2020. The random-effects model was used to calculate the effect sizes of the included studies. The risk of bias of included studies was assessed using the Cochrane collaboration’s tool. Besides, the NutriGrade scoring system was applied to judge the credibility of the evidence. Findings In total, 18 studies (with 1,250 participants) were included in the meta-analysis. The pooled analysis revealed that garlic supplementation has a significant increase in body weight [weighted mean difference (WMD) = 0.31 Kg, 95% CI: 0.09, 0.53 Kg, P = 0.005, n = 12 effect sizes]. Waist circumference (WC) does remarkably reduce [WMD = −1.28 cm, 95% CI: −2.08, −0.47 cm, P = 0.002, n = 4 effect size]. However, body mass index, body fat percent and fat-free mass do not dramatically change (P > 0.05). Notably, the pooled analyses on body weight and WC were sensitive to two included studies. NutriGrade’s score was rated low for this meta-analysis. Originality/value Although garlic supplementation could slightly increase weight and simultaneously might decrease WC, these associations were not strong enough to corroborate the findings. Also, other anthropometric indices do not significantly change. Further well-designed randomized clinical trial studies are needed to confirm the results.