Effects of Quercetin on Adiponectin-Mediated Insulin Sensitivity in Polycystic Ovary Syndrome: A Randomized Placebo-Controlled Double-Blind Clinical Trial

Abstract

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.

Effects of quercetin supplementation on glycemic control among patients with metabolic syndrome and related disorders: A systematic review and meta‐analysis of randomized controlled trials

“…In a study by Khorshidi et al (), the use of 1,000‐mg quercetin supplements in overweight or obese women with PCOS could significantly decrease FBG, insulin, and HOMA‐IR in the quercetin group, but no significant difference was seen between two groups. Furthermore, quercetin supplementation at a dosage of 1 g/day to women with PCOS for 12 weeks was effective in improving the adiponectin‐mediated insulin resistance, fasting glucose, and insulin levels (Rezvan et al, ). However, supplementation with a supra‐nutritional dose of 162‐mg/day quercetin in overweight‐to‐obese subjects with (pre‐)hypertension for 6 weeks did not affect fasting glucose, insulin, and HOMA‐IR (Brull et al, ).…”

“…Some randomized controlled trials (RCTs) have investigated the effects of quercetin on glucose homeostasis in patients with metabolic disorders, whereas the results are conflicted. In a study conducted by Rezvan, Moini, Gorgani‐Firuzjaee, & Hosseinzadeh‐Attar (), quercetin administration at a dosage of 1,000 mg/day for 12 weeks significantly reduced fasting plasma glucose (FPG), serum insulin levels, and insulin resistance in women with polycystic ovarian syndrome (PCOS). Brull et al () found that quercetin intake at a daily dosage of 162 mg after 12 weeks did not affect glucose level in people who were overweight and had hypertension.…”

Safety Aspects of the Use of Quercetin as a Dietary Supplement

“…At least the information that no adverse events were reported by the enrolled individuals is given after the repeated intake of 500 mg quercetin per day for 4–8 weeks ( n Q = 20–22), 730 mg for 4 weeks (n Q = 41) or 1000 mg for 5 d, for at least 2 weeks (no further information on duration of quercetin dosage) or for 12 weeks ( n Q = 11–42) . After intake of 1000 mg quercetin per day for 1 month conducted in patients with chronic pelvic pain syndrome ( n Q = 15), one patient developed headaches after the first few quercetin doses which resolved and one individual experienced mild tingling of the extremities after each quercetin dose …”

Assessment of the Relationship Between Serum High Molecular Weight Adiponectin Hormone Levels and Insulin Resistance in Patients with Polycystic Ovary Syndrome

“…Similarly, a more recent study has shown that quercetin supplementation reduced the HOMA-IR and insulin, and improved the hormonal profile in PCOS patients. The results of this study revealed that quercetin is able to increase total adiponectin and HMWA levels without changing BMI and WHR [29].…”