The Effects of Nigella sativa and curcumin supplementation on oxidative stress biomarkers in postmenopausal women with primary osteoporosis or osteopenia: A triple-blind factorial randomized controlled trial

Background: Herbal products with potential antioxidant effects can be used in the management of chronic disorders such as osteoporosis. Objectives: The aim of this study was to evaluate the effects of Nigella sativa (NS) and curcumin (CUR) supplementation on oxidative stress biomarkers in postmenopausal women with primary osteoporosis or osteopenia. Methods: In this randomized controlled trial, conducted from August 2018 to April 2019 using a triple-blind factorial design, 120 postmenopausal women with primary osteoporosis (n = 74) or osteopenia (n = 46) were randomly allocated to 430 person groups, namely the NS, CUR, NS + CUR, and placebo groups. Participants in these groups daily received one 1000 mg NS oil capsule and one CUR placebo capsule, one 80 mg nanomicelle CUR and one NS placebo capsule, one 1000 mg NS oil capsule and one 80 mg nanomicelle CUR capsule, and two placebo capsules, respectively. The intervention lasted 6 months. The serum levels of the superoxide dismutase (SOD), total antioxidant capacity (TAC), and malondialdehyde (MDA) oxidative stress biomarkers were assessed before and after the intervention. Results: SOD serum level significantly increased in the NS and the NS + CUR groups and its posttest value in the NS + CUR group was significantly more than the placebo group (mean differences = 100.4, 95% confidence interval = 21.9–178.9; P = 0.013). TAC serum level significantly increased in the NS + CUR group and its posttest value in this group was significantly more than the placebo group (mean difference = 0.23; 95% confidence interval = 0.05–0.41; P = 0.011). No significant change was observed in MDA serum level in any of the study groups (P > 0.05). Conclusion: CUR is probably ineffective in significantly reducing oxidative stress, while NS can relatively alleviate oxidative stress and NS + CUR can considerably alleviate oxidative stress in postmenopausal women with primary osteoporosis or osteopenia.