Abstract
Vitamin D is an essential vitamin for normal bone growth and development in humans. The aims of this study were to determine the extent of vitamin D deficiency and insufficiency in Saudi Arabian boys and girls and to investigate the impact of low vitamin D status and poor lifestyle habits on the markers of bone health in this age group. The project involved 300 healthy school children aged 6-18 years, living in Jeddah. Vitamin D status, bone profile and markers was measured together with bone mineral density (BMD) and bone mineral content (BMC), were determined by using dual-energy x-ray absorptiometry (DXA). Calcaneal bone mass was measured by broadband ultrasound attenuation (BUA), Lifestyle factors including the duration of sunshine exposure, physical activity, dress style and onset of veiling for girls was assessed in relation to vitamin D status. Nutritional intake was assessed using a food frequency questionnaire. Results showed that vitamin D deficiency was significantly higher in girls than in boys. The overall prevalence of vitamin D deficiency was significantly higher in girls than in boys: ~ 71% of all groups had low levels of vitamin D (< 50 nmol/L), 42. 7% of boys and 93. 3% of girls had low levels. There was an inverse association between vitamin D and parathyroid hormone and girls. Individual habits strongly affected the levels of vitamin D in our study samples. A significant difference existed between boys and girls in terms of BMD, BMC and BUA; but no difference in the Z-score between boys and girls. Hypovitaminosis, lack of exposure to the sun, sedentary lifestyle are common in Saudi adolescents, which may confer an increased risk for early osteoporosis. There is an urgent need to develop population-based health strategies to the risks associated with Vitamin D deficiency.