title: Vitamin D deficiency in Crohn's disease and healthy controls: a prospective case-control study in the Netherlands.
abstract: OBJECTIVE
  Vitamin D deficiency has been observed in a wide range of medical conditions including Crohn's disease (CD). We aimed to assess whether CD patients have lower vitamin D levels than healthy controls, and to determine risk factors for vitamin D deficiency.
  
  
  METHODS
  25(OH)D was measured by chemiluminescent immunoassay in serum obtained from 101 CD patients and 41 controls. Demographics, sunlight exposure, dietary vitamin D intake, comorbidities and medication were recorded using validated questionnaires. In CD patients the Harvey-Bradshaw index, Montreal classification and surgical resections were also evaluated. 25(OH)D levels of > 75 nmol/L, between 50 and 75 nmol/L and < 50 nmol/L were considered as normal, suboptimal and deficient, respectively.
  
  
  RESULTS
  Vitamin D levels were rather low but comparable among CD patients and controls (mean 25(OH)D 51.6 nmol/L(± 26.6) in CD, and 60.8 nmol/L(± 27.6) in controls. Multivariate regression analysis revealed BMI, sun protection behaviour, non-Caucasian ethnicity, no use of tanning beds, and no holidays in the last year as significantly associated with serum 25(OH)D levels in CD patients (R=0.62). In the control group no statistically significant factors were identified that had an impact on 25(OH)D serum levels.
  
  
  CONCLUSIONS
  Vitamin D deficiency is common in CD patients, but also in healthy controls. Appropriate vitamin D screening should be advised in patients with CD. Moreover, the positive effect of sunlight on the vitamin D status should be discussed with CD patients, but this should be balanced against the potential risk of developing melanomas, especially in patients using thiopurines.
authors.affiliation: Dept. of Gastroenterology and Hepatology, Academic Medical Center (AMC) Amsterdam, The Netherlands.
authors.forename: Jessica R
authors.initials: JR
authors.lastname: de Bruyn
authors.affiliation: Dept. of Gastroenterology and Hepatology, Academic Medical Center (AMC) Amsterdam, The Netherlands.
authors.forename: Rosanne
authors.initials: R
authors.lastname: van Heeckeren
authors.affiliation: Dept. of Gastroenterology and Hepatology, Academic Medical Center (AMC) Amsterdam, The Netherlands.
authors.forename: Cyriel Y
authors.initials: CY
authors.lastname: Ponsioen
authors.affiliation: Dept. of Gastroenterology and Hepatology, Academic Medical Center (AMC) Amsterdam, The Netherlands.
authors.forename: Gijs R
authors.initials: GR
authors.lastname: van den Brink
authors.affiliation: Dept. of Gastroenterology and Hepatology, Academic Medical Center (AMC) Amsterdam, The Netherlands.
authors.forename: Mark
authors.initials: M
authors.lastname: Löwenberg
authors.affiliation: Dept. of Gastroenterology and Hepatology, Academic Medical Center (AMC) Amsterdam, The Netherlands.
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Bredenoord
authors.affiliation: Dept. of Occupational Health, Safety and Environment, Academic Medical Center (AMC) Amsterdam, The Netherlands.
authors.forename: Gerard
authors.initials: G
authors.lastname: Frijstein
authors.affiliation: Dept. of Gastroenterology and Hepatology, Academic Medical Center (AMC) Amsterdam, The Netherlands. Electronic address: g.dhaens@amc.uva.nl.
authors.forename: Geert R
authors.initials: GR
authors.lastname: D'Haens
mesh_terms: D000328:Adult; D015992:Body Mass Index; D016022:Case-Control Studies; D003424:Crohn Disease / Q000097:blood* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011446:Prospective Studies; D012307:Risk Factors; D013472:Sunlight; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000453:epidemiology / Q000208:ethnology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: 25(OH)D; Crohn's disease; Inflammatory bowel disease; Vitamin D