Curcuminoids Lower Plasma Leptin Concentrations: A Meta-analysis.

Curcumin is a naturally occurring polyphenol that has been suggested to improve several metabolic diseases. Leptin is an adipokine involved in metabolic status and appetite, with marked crosstalk with other systems. Available data suggest that curcumin may affect leptin levels; therefore, this meta-analysis was performed to evaluate this. A systematic review and meta-analysis were undertaken on all randomized controlled trials of curcumin studies that included the measurement of leptin. The search included PubMed-Medline, Scopus, ISI Web of Knowledge, and Google Scholar databases. Quantitative data synthesis was performed by using a random-effects model, with standardized mean difference and 95% confidence interval as summary statistics. A funnel plot, Begg's rank correlation, and Egger's weighted regression tests assessed the presence of publication bias. Four eligible articles comprising five treatment arms were selected for the meta-analysis. Meta-analysis showed a significant decrease in plasma leptin concentrations following curcumin treatment (standardized mean difference: -0.69, 95% confidence interval: -1.16, -0.23, p = 0.003; I2  = 76.53%). There was no evidence of publication bias. This meta-analysis showed that curcumin supplementation is associated with a decrease in leptin levels that may be regarded as a potential mechanism for the metabolic effects of curcumin. Copyright © 2017 John Wiley & Sons, Ltd.