Prevalence of vitamin D insufficiency and associated factors among Canadian Cree: a cross-sectional study.
Aboriginal peoples affected by a nutrition transition and living at high latitudes are among the ethnic groups most at risk of vitamin D deficiency. The objectives of this study were to determine the prevalence of meeting predefined cut-off concentrations of vitamin D and to examine associated factors among James Bay Cree aged ≥ 15 years. A cross-sectional study was conducted between the months of May and September from 2005 to 2009. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were determined by radioimmunoassay. Anthropometrics were measured and additional information on socio-demographic characteristics, lifestyle and dietary habits was obtained using questionnaires. A logistic regression model predicting vitamin D insufficiency (<50 nmol/L) included known covariates. Data were obtained from 944 Cree (406 men (43%); mean age 37.4 years), with an effective participation rate of 49% among women and 41% among men. Mean serum 25(OH)D concentrations (nmol/L) by gender were 52.9 (95% CI 51.4-54.5) in men and 47.5 (95% CI 46.2-48.9) in women, and by age group were 46.0 (95% CI 44.9-48.9) in those 15-39 years and 59.6 (95% CI 57.9-61.4) in those ≥ 40 years of age. Overall, 5.8%, 42.6%, 40.0%, and 11.7% of the participants had 25(OH)D concentrations <30, 30-49.9, 50-74.9 and ≥ 75 nmol/L, respectively. Female gender, obesity, younger age, spring, low fish and milk intake, and low vigorous physical activity predicted vitamin D insufficiency (all p<0.05). The vitamin D status in Eastern James Bay Cree is suboptimal with nearly half of the population having insufficient concentrations for optimum bone health.