title: Sun exposure, vitamin D and age at disease onset in relapsing multiple sclerosis.
abstract: BACKGROUND
  Current evidence suggests that sun exposure and vitamin D intake, during childhood and adolescence, are associated with a reduced risk of multiple sclerosis (MS). However, the role of these environmental agents in the timing of disease symptom onset remains to be investigated.
  
  
  METHODS
  Using a cross-sectional study design, we recruited participants from the Veterans Health Administration-Multiple Sclerosis Surveillance Registry. Self-reported histories of residential locations, sun exposure and intake of vitamin D were used to estimate vitamin-D-related exposures. Multivariable linear regression analysis was used to examine the associations between these variables and age at MS onset.
  
  
  RESULTS
  Among veterans with relapsing MS who resided in low-to-medium solar radiation areas (n = 540), low sun exposure in the fall/winter during the ages of 6-15 years was significantly associated with earlier symptom onset by 2.1 years (p = 0.02). Intake of cod liver oil during the same age period was associated with later onset of MS symptoms by 4 years (p = 0.02).
  
  
  CONCLUSIONS
  The current study provides evidence for an association between vitamin-D-related exposures during childhood and early adolescence and the timing of MS symptom onset, and supports vitamin D as a potential modulator of the clinical course of this disease.
authors.affiliation: MS Center of Excellence-East, Baltimore VAMC, Baltimore, MD 21210, USA. tycmcdowell@hotmail.com
authors.forename: Tzu-Yun
authors.initials: TY
authors.lastname: McDowell
authors.forename: Sania
authors.initials: S
authors.lastname: Amr
authors.forename: William J
authors.initials: WJ
authors.lastname: Culpepper
authors.forename: Patricia
authors.initials: P
authors.lastname: Langenberg
authors.forename: Walter
authors.initials: W
authors.lastname: Royal
authors.forename: Christopher
authors.initials: C
authors.lastname: Bever
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Bradham
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D003060:Cod Liver Oil; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000453:epidemiology* / Q000209:etiology*; D012042:Registries; D012737:Sex Factors; D013472:Sunlight; D011795:Surveys and Questionnaires; D014807:Vitamin D
chemical_list: D014807:Vitamin D; D003060:Cod Liver Oil