Vitamin D deficiency among healthy adolescents in Al Ain, United Arab Emirates

Background: Although vitamin D deficiency has been studied in various adult populations, there are few data on the prevalence of this nutritional deficiency among healthy adolescents in the United Arab Emirates (UAE). This study was conducted to determine the prevalence of vitamin D deficiency and to examine its correlates in adolescents aged 15 to 18 years. Methods: This was a cross-sectional study in urban schools. Healthy adolescents (N=315) from a sample of 8 schools were randomly selected from the 142 schools in Al Ain, Abu Dhabi Emirate. Outcomes measured included serum concentrations of 25-hydroxy vitamin D (25OHD), plasma lipids, blood sugar, blood pressure and anthropometric data, nutrition and lifestyle variables. Results: Fourty-one participants (19.7%) were vitamin D deficient (serum 25OHD level <= 15 ng/mL [<= 37.5 nmol/L]. Using a cutoff level of 25(OH) D of <= 20 ng/ml [<= 50 nmol/l] 143 participants (45.4%) were vitamin D insufficient. Overall 65.1% of study participants were either vitamin D deficient or insufficient. The prevalence of vitamin D deficiency varied between boys (10%) and girls (28%). In a final multivariate model, serum 25(OH) D concentrations were inversely correlated with female gender, consumption of fast food per week, and body mass index and positively correlated with physical activity scores after adjustment for age. Conclusions: Vitamin D deficiency and insufficiency were highly prevalent in adolescents, and more common in girls.