Effects of quercetin on adiponectin-mediated insulin sensitivity in polycystic ovary syndrome : a randomized placebo-controlled double-blind clinical trial

Polycystic ovary syndrome (PCOS) is a heterogeneous, multi-causal, and genetically complex disorder, which is related to the failure in endocrine glands. Adiponectin has been reported to be low in PCOS, even in the absence of adiposity. Quercetin reduces serum glucose, insulin, triglycerides, and cholesterol levels and increases the expression and secretion of adiponectin. The aim of this study was to determine the effect of quercetin on the adiponectin-mediated insulin sensitivity in PCOS patients. Eighty-four women with PCOS were selected and randomly assigned to 2 groups of treatment and control. The treatment group received 1 g quercetin (two 500 mg capsules) daily for 12 weeks, and the control group received placebo. In addition to anthropometric assessments, fasting serum levels of total adiponectin, high-molecular-weight (HMW) adiponectin, glucose, insulin, testosterone, LH, and SHBG were also measured at the baseline and at the end of the trial. Quercetin could slightly increase the level of adiponectin by 5.56% as compared to placebo (adjusted p-value=0.001) and HMW adiponectin by 3.9% as compared to placebo (adjusted p-value=0.017), while it reduced the level of testosterone (0.71 ng/dl in quercetin vs. 0.77 ng/dl in placebo; p<0.001) and LH (8.42 IU/l in quercetin vs. 8.68 IU/l in placebo; p=0.009). HOMA-IR levels were also significantly (p<0.001) lower in quercetin (1.84) group compared to placebo group (2.21). Oral quercetin supplementation was effective in improving the adiponectin-mediated insulin resistance and hormonal profile of women with PCOS.