Expression of Concern: Calcium plus vitamin D supplementation influences biomarkers of inflammation and oxidative stress in overweight and vitamin D‐deficient women with polycystic ovary syndrome: a randomized double‐blind placebo‐controlled clinical trial

Summary Objective This study was conducted to determine the effects of calcium plus vitamin D supplementation on inflammatory factors and biomarkers of oxidative stress among overweight vitamin D‐deficient women with polycystic ovary syndrome ( PCOS ). Design, Patients and Measurements This randomized double‐blind placebo‐controlled clinical trial was performed among 104 overweight vitamin D‐deficient women diagnosed with PCOS aged 18–40 years. Participants were randomly divided into four groups. Group A received 1000 mg calcium daily and vitamin D placebo weekly ( N = 26), group B 50000 IU vitamin D weekly and calcium placebo daily ( N = 26), group C 1000 mg calcium daily plus 50000 IU vitamin D weekly ( N = 26) and group D calcium placebo daily plus vitamin D placebo weekly ( N = 26) for 8 weeks. Fasting blood samples were taken at baseline and 8 weeks after intervention to measure inflammatory factors and biomarkers of oxidative stress. Results After 8 weeks, individuals taking calcium plus vitamin D supplements had greater decreases in homoeostatic model assessment beta‐cell function ( HOMA ‐B) score (−11·1 vs −8·6, −3·4 and 13·7, respectively, P = 0·03), serum high‐sensitivity C‐reactive protein (hs‐ CRP ) (−948·3 vs 802·3, −383·8 and 618·2 ng/ml, respectively, P = 0·04) and plasma malondialdehyde ( MDA ) concentrations (−0·6 vs −0·5, −0·1 and 0·6 μmol/l, respectively, P = 0·009), and significant increases in plasma total antioxidant capacity ( TAC ) (35·2 vs 21·1, 22·5 and −153·8 mmol/l, respectively, P = 0·006) and glutathione ( GSH ) levels (216·0 vs 3·9, −47·5 and −160·8 μmol/l, respectively, P = 0·001) compared with calcium alone, vitamin D alone and placebo groups. Calcium plus vitamin D cosupplementation did not influence plasma NO and catalase levels. Conclusions We found that calcium plus vitamin D cosupplementation for 8 weeks among overweight and vitamin D‐deficient women with PCOS had beneficial effects on inflammatory factor and biomarkers of oxidative stress.