title: Higher predicted vitamin D status is associated with reduced risk of Crohn's disease.
abstract: OBJECTIVE
  Vitamin D influences innate immunity, which is believed to be involved in the pathogenesis of Crohn's disease (CD) and ulcerative colitis (UC). However, data examining vitamin D status in relation to risk of CD and UC are lacking.
  
  
  METHODS
  We conducted a prospective cohort study of 72,719 women (age, 40-73 y) enrolled in the Nurses' Health Study. In 1986, women completed an assessment of diet and lifestyle, from which a 25-hydroxy vitamin D [25(OH)D] prediction score was developed and validated against directly measured levels of plasma 25(OH)D. Through 2008, we confirmed reported diagnoses of incident CD or UC through medical record review. We used Cox proportional hazards modeling to examine the hazard ratio (HR) for incident CD or UC after adjusting for potential confounders.
  
  
  RESULTS
  During 1,492,811 person-years of follow-up evaluation, we documented 122 incident cases of CD and 123 cases of UC. The median predicted 25(OH)D level was 22.3 ng/mL in the lowest and 32.2 ng/mL in the highest quartiles. Compared with the lowest quartile, the multivariate-adjusted HR associated with the highest quartile of vitamin D was 0.54 (95% confidence interval [CI], 0.30-.99) for CD (P(trend) = .02) and 0.65 (95% CI, 0.34-1.25) for UC (P(trend) = .17). Compared with women with a predicted 25(OH)D level less than 20 ng/mL, the multivariate-adjusted HR was 0.38 (95% CI, 0.15-0.97) for CD and 0.57 (95% CI, 0.19-1.70) for UC for women with a predicted 25(OH)D level greater than 30 ng/mL. There was a significant inverse association between dietary and supplemental vitamin D and UC, and a nonsignificant reduction in CD risk.
  
  
  CONCLUSIONS
  Higher predicted plasma levels of 25(OH)D significantly reduce the risk for incident CD and nonsignificantly reduce the risk for UC in women.
authors.affiliation: Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02214, USA.
authors.forename: Ashwin N
authors.initials: AN
authors.lastname: Ananthakrishnan
authors.forename: Hamed
authors.initials: H
authors.lastname: Khalili
authors.forename: Leslie M
authors.initials: LM
authors.lastname: Higuchi
authors.forename: Ying
authors.initials: Y
authors.lastname: Bao
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Korzenik
authors.forename: Edward L
authors.initials: EL
authors.lastname: Giovannucci
authors.forename: James M
authors.initials: JM
authors.lastname: Richter
authors.forename: Charles S
authors.initials: CS
authors.lastname: Fuchs
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Chan
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D003093:Colitis, Ulcerative / Q000097:blood / Q000453:epidemiology* / Q000276:immunology; D003424:Crohn Disease / Q000097:blood / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control; D005260:Female; D006306:Health Surveys; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013997:Time Factors; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology* / Q000276:immunology
chemical_list: D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D