The Effects of Melatonin Intake on Biomarkers of Inflammation and Oxidative Stress in Subjects with Breast Cancer: A Randomized, Double-Blind, Placebo-Controlled Trial

Abstract Background: To our knowledge, data on the effects of melatonin supplementation on biomarkers of inflammation and oxidative stress in subjects with breast cancer are scarce. This research was done to assess the effects of melatonin supplementation on biomarkers of inflammation and oxidative stress in subjects with breast cancer. Methods: This randomized double-blind, placebo-controlled trial was conducted on 40 subjects diagnosed with breast cancer aged >25 years old. Subjects were randomly assigned into two groups to take either melatonin (n=20) or placebo (n=20) for 24 weeks. Inflammation and oxidative stress biomarkers were quantified at baseline and after the 24-week intervention. Results: After the 24-week intervention, compared with the placebo, melatonin supplementation significantly increased plasma total antioxidant capacity (TAC) (+21.3±26.2 vs. -6.3±34.5 mmol/L, P=0.007), and decreased plasma malondialdehyde (MDA) concentrations (-0.2±0.3 vs. +0.1±0.2 µmol/L, P=0.002). We did not observe any significant effect of melatonin supplementation on other biomarkers of oxidative stress. Conclusions: Overall, melatonin intake for 24 weeks in patients with breast cancer had beneficial effects on TAC and MDA levels, but did not affect other biomarkers of oxidative stress.