GARLIC SUPPLEMENTATION REDUCES C-REACTIVE PROTEIN, TUMOR NECROSIS FACTOR AND INTERLEUKIN 6 IN ADULTS: A SYSTEMATIC REVIEW AND META-ANALYSIS OF RANDOMIZED CONTROLLED TRIALS

Background and Aim: Conflicting findings have been obtained from Randomized clinical trials (RCT) on the effects of garlic supplementation on inflammatory biomarkers. No previous study has systematically summarized studies in this area. Therefore, the aim of this systematic review was to summarize findings for the effects of garlic supplementation on serum concentrations of inflammatory biomarkers in adults.Methods: Scopus, PubMed, Google Scholar and Cochrane library databases were searched for relevant papers published up to April 2018, using suitable keywords. RCTs that examined the effect of garlic supplementation on inflammatory cytokines in adults were included.Results: Sixteen RCTs were included. The garlic dose ranged from 12 to 3600 mg/d, and intervention duration varied from 2 to 52 wk. Garlic administration significantly reduced serum C-reactive protein(CRP)(n=13) [WMD: -0.61 mg/L, 95% CI: -1.12 to -0.10, P=0.018, I2=76.9%], interleukin-6 (IL-6) (n=5) (WMD: -0.73 ng/L, 95% CI: -1.06 to -0.40, P<0.001 , I2=0%) and tumor necrosis factor (TNF)(n=7) (WMD: -0.26 ng/L, 95% CI: -0.41, -0.11, P<0.001, I2=0.0%), as compared to control. However, the effect of garlic supplementation on serum adiponectin(n=3) (WMD: 0.18 µg/L, 95% CI: -0.21, 0.57, P = 0.35, I2=60.7%) and leptin(n=2) (WMD: -1.25 µg/L, 95% CI: -2.64, 0.14, P = 0.07, I2=0.0%) concentrations were not significant.Conclusion: Garlic supplementation reduced serum concentrations of CRP, TNF, IL-6, without changes in adiponectin and leptin concentrations. More RCTs are needed to shed light in this issue.

Keywords:

Garlic , Inflammation , Cytokine , Diet , Meta-analysis