title: Higher vitamin D intake is needed to achieve serum 25(OH)D levels greater than 50 nmol/l in Québec youth at high risk of obesity.
abstract: OBJECTIVE
  Vitamin D levels are often observed to be low in Canadian youth, despite the mandatory fortification of fluid milk. We identified modifiable correlates of plasma vitamin D concentrations to inform public health efforts to remediate low-vitamin D status.
  
  
  METHODS
  We recruited 159 children aged 8-11 years, who were at at high risk of obesity, non-systematically during different seasons. Vitamin D status was assessed by measuring plasma 25-hydroxyvitamin D (25(OH)D) using a radioimmunoassay. Dietary intake, including vitamin supplements, was measured using three dietitian-administered 24 h diet recalls. Fat mass was measured by dual energy X-ray absorptiometry. Accelerometers were worn for 7 days to estimate physical activity. Independent correlates of plasma 25(OH)D concentrations were identified using multiple regression in an analysis controlling for season of measurement.
  
  
  RESULTS
  Approximately, 7% of youth had hypovitaminosis D (25(OH)D ≤37.5 nmol/l) during winter and spring when vitamin D levels are at their nadir. Only 55% of participants had vitamin D levels, which the Institute of Medicine considers optimal (25(OH)D >50 nmol/l). The mean dietary vitamin D intake, 6.6 mcg, was well below current recommendations set at 15 mcg. A serving increase in milk consumption and a s.d. increase in physical activity were associated with only a 2.9 and 2.1 nmol/l increase in plasma 25(OH)D, respectively. There was no association between 25(OH)D and adiposity.
  
  
  CONCLUSIONS
  Our results indicate the challenges of obtaining adequate vitamin D intake from the current food supply to support a level of 25(OD)D >50 nmol/l.
authors.affiliation: School of Dietetics and Human Nutrition, McGill University, Montreal, Quebec, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Mark
authors.forename: M
authors.initials: M
authors.lastname: Lambert
authors.forename: E E
authors.initials: EE
authors.lastname: Delvin
authors.forename: J
authors.initials: J
authors.lastname: O'Loughlin
authors.forename: A
authors.initials: A
authors.lastname: Tremblay
authors.forename: K
authors.initials: K
authors.lastname: Gray-Donald
mesh_terms: D015502:Absorptiometry, Photon; D050154:Adiposity / Q000187:drug effects; D002648:Child; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D009751:Nutritional Requirements; D009765:Obesity / Q000453:epidemiology*; D015995:Prevalence; D011792:Quebec / Q000453:epidemiology; D012279:Rickets / Q000453:epidemiology / Q000517:prevention & control; D012307:Risk Factors; D012621:Seasons; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000517:prevention & control
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D