Vitamin D deficiency is associated with disability and disease progression in multiple sclerosis patients independently of oxidative and nitrosative stress

The aim of this study was to assess vitamin D status in patients with multiple sclerosis (MS) and to evaluate whether it was associated with oxidative and nitrosative stress (O&NS) markers and disability. This study included 137 patients with MS and 218 healthy controls. The markers evaluated were serum levels of 25-hydroxyvitamin D, lipid hydroperoxides, advanced oxidation protein products (AOPP), nitric oxide metabolites (NOx), and total radical-trapping antioxidant parameter TRAP/UA. Patients with 25(OH)D < 20 ng/mL showed higher EDSS (p = 0.016), MSSS (p = 0.005) and lower AOPP (p = 0.046) than those with 25(OH)D ≥ 20 ng/mL. After the binary logistic regression analyses, EDSS and MSSS remained significantly associated with vitamin D deficiency. We showed that lower levels of 25(OH)D were associated with higher EDSS and MSSS independently of variables such as O&NS, age, sex, body mass index, ethnicity, MS therapy, use of interferon beta, and clinical forms of MS (odds ratio: 1.380, 95% confidence interval 1.030-1.843, p = 0.031). Moreover, the study showed an association between serum levels of 25(OH)D and EDSS (r2 = 0.115, p = 0.002), demonstrating that 25(OH)D may contribute with 11.5% of increase in EDSS. Our results suggest that vitamin D deficiency may be considered one of the predictors of the disability in MS patients, independently of their redox status and influence the progression of disability in MS.