Comprehensive Effects of Melatonin Supplementation on Cardiometabolic Risk Factors: A Systematic Review and Dose-Response Meta-Analysis
Abstract
Background/Objectives: There is no definitive consensus regarding the effects of melatonin on cardiometabolic risk factors (CMRFs). This systematic review and dose-response meta-analysis of randomized controlled trials (RCTs) evaluated the impacts of melatonin supplementation on CMRFs, including anthropometric, lipid, glycemic, inflammatory, oxidative, and liver function parameters. Methods: A systematic search across multiple databases retrieved 63 eligible RCTs published up to October 2025. Results: This random-effects meta-analysis indicated that melatonin supplementation significantly reduced hip circumference (weighted mean difference (WMD): -1.18 cm, 95% confidence interval (CI): -2.28, -0.08), systolic blood pressure (WMD: -2.34 mmHg, 95% CI: -4.13, -0.55), fasting blood glucose (WMD: -11.63 mg/dL, 95% CI: -19.16, -4.10), low-density lipoprotein cholesterol (WMD: -6.28 mg/dL, 95% CI: -10.53, -2.03), total cholesterol (WMD: -6.97 mg/dL, 95% CI: -12.20, -1.74), C-reactive protein (WMD: -0.59 mg/L, 95% CI: -0.94, -0.23), malondialdehyde (WMD: -1.54 μmol/L, 95% CI: -2.07, -1.01), tumor necrosis factor-alpha (WMD: -1.61 pg/mL, 95% CI: -2.31, -0.90), interleukin-6 (WMD: -6.43 pg/mL, 95% CI: -10.72, -2.15), and alanine aminotransferase (WMD: -2.61 IU/L, 95% CI: -4.87, -0.34). Supplementation with melatonin substantially increased serum total antioxidant capacity (WMD: 0.15 mmol/L, 95% CI: 0.08, 0.22) and high-density lipoprotein cholesterol (WMD: 2.04 mg/dL, 95% CI: 0.50,…
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