Hypovitaminosis D in healthy schoolchildren

Background. Vitamin D is essential for skeletal growth, but there are curre ntly no guidelines for vitamin D supplementation after infancy. This study investigates vitamin D insufficiency in healthy children. Methods. Children ages 10 to 16 years from 3 private schools in Beirut, Leb anon, with differing socioeconomic status (SES) were studied: 169 in the sp ring of 1999 and 177 in the following fall; 83 students participated in bot h study phases. They had a physical examination, answered a dietary questio nnaire, and blood was drawn for calciotropic hormones and indices of bone t urnover. Results. Overall, 52% of the students were vitamin D-insufficient; the prop ortion of insufficiency was 65% in the winter and 40% at the end of the sum mer. During both seasons, girls had lower vitamin D levels than did boys; t hose who followed the dress code of covered head, arms, and legs had the lo west levels. Students in the mid-SES school had lower 25-hydroxyvitamin D ( 25-OHD) levels than did the ones from the high-SES school. After adjusting for confounders, gender, SES, and body mass index remained the significant predictors of vitamin D levels in both seasons (R-2 = 0.53, for spring and 0.28 for fall). There was a significant inverse correlation between 25-OHD levels and parathyroid hormone levels that was best fitted by a curvilinear model (R-2 = 0.19). Conclusion. Even in a sunny country, hypovitaminosis D is common in schoolc hildren, more so in the winter. Girls, especially those with a lower SES, a re at particular risk. The inverse changes in parathyroid hormone suggest t hat insufficient vitamin D levels may deleteriously affect skeletal metabol ism in healthy adolescents. Vitamin D insufficiency may be prevalent in man y other countries where supplementation of milk with vitamin D is not manda tory. Our results call to a reconsideration of vitamin D supplementation in high-risk adolescents to further optimize skeletal health.