title: A systematic review of randomized, double-blind, placebo-controlled trials examining the clinical efficacy of vitamin D in multiple sclerosis.
abstract: BACKGROUND
  An association between multiple sclerosis (MS) prevalence as well as MS mortality and vitamin D nutrition has led to the hypothesis that high levels of vitamin D could be beneficial for MS. The purpose of this systematic review is to establish whether there is evidence for or against vitamin D in the treatment of MS.
  
  
  METHODS
  Systematic literature searches were performed to locate randomized, placebo-controlled, double-blind trials measuring the clinical effect of vitamin D on MS in human participants. Data were extracted in a standardized manner, and methodological quality was assessed by the Jadad score.
  
  
  RESULTS
  Five trials were located that met the selection criteria. Of the 5 trials, 4 showed no effect of vitamin D on any outcome, and 1 showed a significant effect, namely by a reduction in the number of T1 enhancing lesions on brain magnetic resonance imaging. Three studies commented on adverse effects of vitamin D, with gastrointestinal adverse effects being the most frequently reported. The literature is limited by small study sizes (ranging from 23 to 68 patients), heterogeneity of dosing, form of vitamin D tested (vitamin D3 in 4 trials and vitamin D2 in 1) and clinical outcome measures. Therefore, a meta-analysis was not performed.
  
  
  CONCLUSIONS
  The evidence for vitamin D as a treatment for MS is inconclusive. Larger studies are warranted to assess the effect of vitamin D on clinical outcomes in patients with MS. We further encourage researchers to also test the effect of vitamin D on the health-related quality of life experienced by patients and their families.
authors.affiliation: Department of Neurology, University Hospital 12 de Octubre, Madrid, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Pozuelo-Moyano
authors.forename: Julián
authors.initials: J
authors.lastname: Benito-León
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Mitchell
authors.forename: Jesús
authors.initials: J
authors.lastname: Hernández-Gallego
mesh_terms: D000818:Animals; D004311:Double-Blind Method; D006801:Humans; D009103:Multiple Sclerosis / Q000097:blood / Q000188:drug therapy* / Q000453:epidemiology; D016032:Randomized Controlled Trials as Topic / Q000379:methods; D016896:Treatment Outcome; D014807:Vitamin D / Q000097:blood / Q000627:therapeutic use*
chemical_list: D014807:Vitamin D