title: Vitamin D deficiency in school-age children is associated with sociodemographic and lifestyle factors.
abstract: BACKGROUND
  There is concern about a reemergence of vitamin D deficiency in children in developed countries.
  
  
  OBJECTIVE
  The aims of this study were to describe vitamin D status in the Generation R study, a large multiethnic cohort of 6-y-old children in The Netherlands, and to examine sociodemographic, lifestyle, and dietary determinants of vitamin D deficiency.
  
  
  METHODS
  We measured serum 25-hydroxyvitamin D [25(OH)D] concentrations in 4167 children aged 6 y and defined deficiency following recommended cutoffs. We examined the associations between subject characteristics and vitamin D deficiency with the use of multivariable logistic regression analyses.
  
  
  RESULTS
  Serum 25(OH)D concentrations ranged from 4 to 211 nmol/L (median: 64 nmol/L), with 6.2% of the children having severely deficient (<25 nmol/L), 23.6% deficient (25 to <50 nmol/L), 36.5% sufficient (50 to <75 nmol/L), and 33.7% optimal (≥75 nmol/L) 25(OH)D concentrations. The prevalence of vitamin D deficiency [25(OH)D <50 nmol/L] was higher in winter (51.3%) than in summer (10.3%); and higher in African, Asian, Turkish, and Moroccan children (54.5%) than in those with a Dutch or other Western ethnic background (17.6%). In multivariable models, several factors were associated with vitamin D deficiency, including household income (OR: 1.74; 95% CI: 1.34, 2.27 for low vs. high income), child age (OR: 1.39; 95% CI: 1.20, 1.62 per year), child television watching (OR: 1.32; 95% CI: 1.06, 1.64 for ≥2 vs. <2 h/d), and playing outside (OR: 0.71; 95% CI: 0.57, 0.89 for ≥1 vs. <1 h/d). In a subgroup with dietary data (n = 1915), vitamin D deficiency was associated with a lower diet quality, but not with vitamin D intake or supplement use in early childhood.
  
  
  CONCLUSIONS
  Suboptimal vitamin D status is common among 6-y-old children in The Netherlands, especially among non-Western children and in winter and spring. Important modifiable factors associated with vitamin D deficiency were overall diet quality, sedentary behavior, and playing outside.
authors.affiliation: Departments of Epidemiology and The Generation R Study Group, Erasmus MC, University Medical Center, Rotterdam, The Netherlands; and trudy.voortman@erasmusmc.nl.
authors.forename: Trudy
authors.initials: T
authors.lastname: Voortman
authors.affiliation: Departments of Epidemiology and.
authors.forename: Edith H
authors.initials: EH
authors.lastname: van den Hooven
authors.affiliation: Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Annemieke C
authors.initials: AC
authors.lastname: Heijboer
authors.affiliation: Departments of Epidemiology and.
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.affiliation: Departments of Epidemiology and Pediatrics, and The Generation R Study Group, Erasmus MC, University Medical Center, Rotterdam, The Netherlands; and.
authors.forename: Vincent Wv
authors.initials: VW
authors.lastname: Jaddoe
authors.affiliation: Departments of Epidemiology and.
authors.forename: Oscar H
authors.initials: OH
authors.lastname: Franco
mesh_terms: D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008019:Life Style; D016015:Logistic Models; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D015596:Nutrition Assessment; D009752:Nutritional Status; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012621:Seasons; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000188:drug therapy / Q000453:epidemiology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: 25-hydroxyvitamin D; children; cohort; determinants; predictors; vitamin D deficiency