title: Association between headache and serum 25-hydroxyvitamin D: the Tromsø Study: Tromsø 6.
abstract: BACKGROUND
  High prevalence of headache has been associated with high latitude, thus suggesting a relation with vitamin D. However, there are so far no reports on the association between serum 25-hydroxyvitamin D (25[OH]D) and headache.
  
  
  OBJECTIVE
  To investigate the association between headache and serum 25(OH)D in a general population.
  
  
  METHODS
  Cross-sectional study based on questionnaires from 11,614 persons who participated in the sixth survey of the Tromsø Study (Tromsø 6) carried out in 2007-2008. The data were stratified according to smoking status and analyzed with regard to migraine and non-migraine headache. Adjustments were done for age, body mass index (BMI), gender, season, chronic diseases, education, physical exercise, and alcohol consumption.
  
  
  RESULTS
  Headache of non-migraine type was associated with low levels of serum 25(OH)D with an odds ratio (OR) of 1.20 (1.04-1.39) in the lowest quartile as compared to the highest serum 25(OH)D quartile. No significant association was found between migraine and serum 25(OH)D.
  
  
  CONCLUSIONS
  Non-migraine headache was associated with low levels of serum 25(OH)D. Although adjustment were done for possible confounders, this finding may still reflect lifestyle rather than causality, and further studies are needed to investigate this. No association was found between serum 25(OH)D and migraine.
authors.affiliation: Division of Internal Medicine, University Hospital of North Norway, Tromsø, Norway. marie.kjaergaard@unn.no
authors.forename: Marie
authors.initials: M
authors.lastname: Kjaergaard
authors.forename: Anne Elise
authors.initials: AE
authors.lastname: Eggen
authors.forename: Ellisiv B
authors.initials: EB
authors.lastname: Mathiesen
authors.forename: Rolf
authors.initials: R
authors.lastname: Jorde
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D005260:Female; D006261:Headache / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D