Abstract
Vitamin D deficiency has been related to the pathogenesis and clinical course of multiple sclerosis (MS), especially with relapse frequency. Hence, a prospective cohort study explored the relationship between serum vitamin D level and MS relapses in 120 patients in a two-year follow-up. Baseline and follow-up serum 25-hydroxyvitamin D were measured and relapse events registered and examined. The result indicated a strong negative correlation between the frequency of relapse and vitamin D (p < 0.01), such that patients with low levels of vitamin (<20 ng/mL) had higher frequencies of relapse.