title: Higher levels of 25-hydroxyvitamin D are associated with a lower incidence of multiple sclerosis only in women.
abstract: BACKGROUND
  Multiple sclerosis (MS) is a chronic inflammatory disease with an as yet not fully understood etiological background. The geographical distribution of MS is striking with a prevalence that increases with latitude. For this reason, vitamin D deficiency is considered a possible pathogenic co-factor in MS.
  
  
  METHODS
  To study the role of the vitamin D metabolism in MS, blood samples were taken twice (summer and winter) from 103 patients with MS and 110 healthy controls. Serum concentrations of 25-hydroxyvitamin D (25(OH) D) and 1,25-dihydroxyvitamin D (1,25(OH)(2)D) were measured, and detailed information on disease characteristics and environmental factors that might influence the vitamin D metabolite levels was collected.
  
  
  RESULTS
  Mean serum 25(OH)D and 1,25(OH)(2)D concentrations were significantly higher in summer compared to winter in both patients and controls. Using logistic regression methods, we found that in women for every 10 nmol/L increase of serum 25(OH)D level the odds of MS was reduced by 19% (odds ratio 0.81; 95% confidence interval: 0.69-0.95), suggesting a "protective" effect of higher 25(OH)D serum levels. In addition, also restricted to women, a negative correlation was found between Expanded Disability Status Scale and 25(OH)D levels (r = -0.29, P = 0.020).
  
  
  CONCLUSIONS
  Our data suggest that higher circulating levels of 25(OH)D are associated with a lower incidence of MS and MS-related disability in women. This may imply clues to the pathogenesis of the sex difference in risk and to the nature of the environmental factors involved in MS.
authors.affiliation: Department of Neurology, VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Jj
authors.initials: J
authors.lastname: Kragt
authors.forename: Bm
authors.initials: B
authors.lastname: van Amerongen
authors.forename: J
authors.initials: J
authors.lastname: Killestein
authors.forename: Cd
authors.initials: C
authors.lastname: Dijkstra
authors.forename: Bmj
authors.initials: B
authors.lastname: Uitdehaag
authors.forename: Ch
authors.initials: Ch
authors.lastname: Polman
authors.forename: P
authors.initials: P
authors.lastname: Lips
mesh_terms: D000328:Adult; D004777:Environment; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000097:blood* / Q000453:epidemiology*; D015995:Prevalence; D012307:Risk Factors; D040242:Risk Reduction Behavior; D012621:Seasons; D017678:Sex Distribution; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D