title: Vitamin D levels and associated factors: a population-based study in Switzerland.
abstract: OBJECTIVE
  To update the prevalence of vitamin D insufficiency and to identify factors associated with vitamin D status in the Swiss adult population.
  
  
  METHODS
  Data from the 2010-2011 Swiss Study on Salt intake, a population-based study in the Swiss population, was used. Vitamin D concentration in serum was measured by liquid chromatography- tandem mass spectrometry. Major factors that influence vitamin D levels were taken into account. Survey statistical procedures were used to estimate means and prevalences of vitamin D levels and status. Monthly-specific tertiles of vitamin D and ordinal logistic regression were used to determine the associations of covariates of interest with vitamin D status.
  
  
  RESULTS
  The prevalences of vitamin D insufficiency (serum 25-hydroxyvitamin D: 20-29.9 ng/ml) and deficiency (<20 ng/ml) were the highest in the January-March period; 26.4% (95%CI: 21.6-31.7) and 61.6% (95%CI: 56.0-67.0), respectively. In the same period, more than 9 of ten men were vitamin D insufficient or deficient. Each unit increase of Body Mass Index was associated with an 8% decreased likelihood of being in a higher vitamin D tertiles. Oral contraceptive, altitude, urinary excretion of calcium, use of vitamin D supplement or treatment, high wine consumption, physical activity were associated with vitamin D tertiles. Compared to the French-speaking region, the Italian-speaking region was independently associated with a higher likelihood of being in higher vitamin D tertiles (OR: 1.66, 95%CI: 1.14-2.43).
  
  
  CONCLUSIONS
  Low levels of vitamin D are common among Swiss adults, in particular during winter months and outside the Italian-speaking region.
authors.affiliation: Community Prevention Unit, Institute of Social and Preventive Medicine (IUMSP), Lausanne University Hospital, Lausanne, Switzerland. idris.guessous@chuv.ch
authors.forename: I
authors.initials: I
authors.lastname: Guessous
authors.forename: V
authors.initials: V
authors.lastname: Dudler
authors.forename: N
authors.initials: N
authors.lastname: Glatz
authors.forename: J M
authors.initials: JM
authors.lastname: Theler
authors.forename: O
authors.initials: O
authors.lastname: Zoller
authors.forename: F
authors.initials: F
authors.lastname: Paccaud
authors.forename: M
authors.initials: M
authors.lastname: Burnier
authors.forename: M
authors.initials: M
authors.lastname: Bochud
mesh_terms: D000293:Adolescent; D000328:Adult; D000531:Altitude; D015992:Body Mass Index; D002118:Calcium / Q000652:urine; D003276:Contraceptives, Oral; D019587:Dietary Supplements; D005260:Female; D006306:Health Surveys; D006801:Humans; D007802:Language; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D015999:Multivariate Analysis; D015995:Prevalence; D012621:Seasons; D013557:Switzerland / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000627:therapeutic use; D014808:Vitamin D Deficiency / Q000097:blood* / Q000453:epidemiology*; D014920:Wine; D055815:Young Adult
chemical_list: D003276:Contraceptives, Oral; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D002118:Calcium