Prevalence and predictors of low vitamin D concentrations in urban Canadian toddlers

Abstract

To determine the prevalence of low vitamin D concentrations in a cohort of healthy two-year-old children living in a large Canadian city, and to explore whether body mass index (BMI) and cow's milk intake are associated with low vitamin D concentrations. A cross-sectional study was performed on healthy two-year-old children attending a well-child visit in Toronto, Ontario (latitude 43.4°N). Dietary exposures were measured by questionnaire. The primary outcome was the prevalence of low vitamin D concentrations (25-hydroxyvitamin D concentration of lower than 50 nmol/L or lower than 75 nmol/L). A total of 91 healthy children 24 to 30 months of age were recruited between November 2007 and May 2008. The prevalence of low vitamin D concentrations (lower than 50 nmol/L) was 32% (29 of 92, 95% CI 22% to 42%) and the prevalence of vitamin D concentrations of lower than 75 nmol/L was 82% (75 of 91, 95% CI 73% to 89%). Using multivariable logistic regression, the odds of vitamin D concentrations being lower than 50 nmol/L decreased by 0.44 (95% CI 0.2 to 0.96) for each additional cup of cow's milk intake per day and increased by 1.2 to 2.6 per unit BMI depending on BMI level (P=0.07). A total of 30% to 80% of toddlers in the present study's urban Canadian setting demonstrated low vitamin D concentrations - the highest prevalence of low vitamin D in toddlers outside of Alaska. Modifiable factors associated with low vitamin D were lower cow's milk intake and higher BMI. The vitamin D status of toddlers in urban Canada may require specific attention.