The role of melatonin supplement in metabolic syndrome: A randomized double blind clinical trial

Purpose Metabolic syndrome contains metabolic disorders that have association with other chronic diseases. Melatonin is a bioactive compound which is found in plants and also produced in the body. The purpose of this paper is to assess the effect of melatonin supplement on metabolic syndrome components, also leptin and adiponectin blood concentrations in patients with metabolic syndrome. Design/methodology/approach A double blind, placebo-controlled, randomized clinical trial was conducted on 70 subjects with metabolic syndrome. Participants received 6 mg/day melatonin or placebo before bedtime for 12 weeks. At the beginning and end of treatment period, blood samples were collected and biochemical parameters were measured. In addition, blood pressure and anthropometric indices were examined before and after the supplementation. Independent sample t-test was used to compare changes in metabolic syndrome components between the two study groups. Findings Results showed a significant reduction in waist circumference (−1.54 vs −0.04 cm; p = 0.036), systolic blood pressure (−3.52 vs 0.79 mmHg; p = 0.020), diastolic blood pressure (−1.50 vs 1.73 mmHg; p = 0.014), serum leptin concentration (−2.54 vs 0.27ng/ml; p = 0.041) and an elevation in high-density lipoprotein cholesterol (2.19 vs −0.79 mg/dl; p = 0.038) in the melatonin group compared to the placebo. Research limitations/implications If insulin concentration had been measured, it might have revealed better interpretation of melatonin effect on fasting blood glucose. Originality/value This study showed that melatonin as a nutritional supplement improved most metabolic syndrome components and concentration of leptin in the melatonin group compared to the placebo.