A Systematic Review and Meta-Analysis of the Effect of Curcuminoids on Adiponectin Levels

Introduction: Curcuminoids are known anti-inflammatory molecules with multiple mechanisms of action while adiponectin is an anti-inflammatory molecule secreted by the adipocytes. Curcuminoids may upregulate the expression of adiponectin and thus modulate their levels in serum. A meta-analysis was performed to identify randomized controlled trials evaluating the effect of curcuminoids on adiponectin concentrations. Materials and methods: The search included PubMed-Medline, Scopus, ISI Web of Science and Google Scholar databases (from inception to October 20, 2018) and the quality of studies was assessed according to Cochrane criteria. Quantitative data synthesis was conducted using a random-effects model and sensitivity analysis by the leave-one out method. Additional analysis was performed to assess the impact of potential confounders on adiponectin levels. Results: The meta-analysis of five randomized clinical trials (n = 686) showed a significant elevation of plasma adiponectin concentrations following supplementation with curcuminoids (WMD: 6.47 ng/mL, 95% CI: 1.85, 11.10, p = 0.010; I2 = 94.85%). The effect size was robust in the leave-one-out sensitivity analysis and the effect size was not driven by a single study in the meta-analysis. Conclusion: This meta-analysis showed a significant increase in plasma levels of adiponectin following curcuminoids therapy, which may be one of the mechanisms of anti-inflammatory activity of curcumin.