25-Hydroxyvitamin D in Canadian adults: biological, environmental, and behavioral correlates

Osteoporos Int. 2011 May;22(5):1389-99. doi: 10.1007/s00198-010-1362-7. Epub 2010 Aug 21.

Abstract

Summary: We assessed vitamin D status and its correlates in the population-based Canadian Multicentre Osteoporosis Study (CaMos). Results showed that serum 25-hydroxyvitamin D levels <75 nmol/L were common. Given Canada's high latitude, attention should be given to strategies for enhancing vitamin D status in the population.

Introduction: Inadequate vitamin D has been implicated as a risk factor for several clinical disorders. We assessed, in a Canadian cohort, vitamin D status and its correlates, based on serum 25-hydroxyvitamin D [25(OH)D], the best functional indicator of vitamin D status.

Methods: We studied 577 men and 1,335 women 35+ years from seven cities across Canada in the randomly selected, population-based Canadian Multicentre Osteoporosis Study (CaMos). Participants completed a comprehensive questionnaire. Serum 25(OH)D was measured by immunoassay. Multivariate linear regression modeling assessed the association between 25(OH)D and determinants of vitamin D status.

Results: Participants (2.3%) were deficient in 25(OH)D (<27.5 nmol/L); a further 18.1% exhibited 25(OH)D insufficiency (27.5-50 nmol/L). Levels <75 nmol/L were evident in 57.5% of men and 60.7% of women and rose to 73.5% in spring (men) and 77.5% in winter (women); 25(OH)D <50 nmol/L was ≤10% year round for those supplementing with ≥400 IU vitamin D/day but was 43.9% among those not supplementing in winter and spring. The strongest predictors of reduced 25(OH)D for both men and women were winter and spring season, BMI ≥30, non-white ethnicity, and lower vitamin D supplementation and its modification by fall and winter.

Conclusions: In this national Canadian cohort, vitamin D levels <75 nmol/L were common, particularly among non-white and obese individuals, and in winter and spring. Vitamin D intake through diet and supplementation and maintenance of normal weight are key modifiable factors for enhancing vitamin D status and thus potentially influencing susceptibility to common chronic diseases.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Distribution
  • Aged
  • Body Mass Index
  • Canada / epidemiology
  • Cross-Sectional Studies
  • Diet / statistics & numerical data
  • Dietary Supplements
  • Female
  • Humans
  • Male
  • Middle Aged
  • Obesity / complications
  • Obesity / epidemiology
  • Seasons
  • Sex Distribution
  • Skin Pigmentation / physiology
  • Sunlight
  • Vitamin D / administration & dosage
  • Vitamin D / analogs & derivatives*
  • Vitamin D / blood
  • Vitamin D Deficiency / blood
  • Vitamin D Deficiency / epidemiology*
  • Vitamin D Deficiency / etiology

Substances

  • Vitamin D
  • 25-hydroxyvitamin D