Vitamin D status is associated with bone mineral density in adolescents: based on Korea National Health and Nutrition Examination Survey

ABSTRACT Vitamin D is a factor that regulates calcium and bone metabolism. However, the clinical effect of vitamin D on bone mineral density (BMD) remains controversial. We hypothesized that sufficient vitamin D level is required to maintain optimal BMD in adolescents. Based on Korea National Health and Nutritional Examination Survey, data of 1,063 adolescents aged 12-18 years were analyzed. The association of vitamin D status and other variables, such as body mass index (BMI), calcium intake, physical activity, lean mass, and fat mass, with BMD Z-scores in the lumbar spine, whole body, total femur, and femur neck were examined. We defined vitamin D deficiency as 20 ng/mL according to the 25-hydroxyvitamin D (25-OHD) level. The mean 25-OHD level of subjects was below normal, at 16.28 ng/mL. Subjects with vitamin D deficiency, insufficiency, and sufficiency comprised 20.5%, 58.6%, and 20.9% of all subjects, respectively. The vitamin D sufficient group had higher BMD Z-scores compared to the insufficient group, and the insufficient group had higher BMD Z-scores compared to the deficient group. In linear regression analysis, 25-OHD level, BMI, calcium intake, physical activity, lean mass, and fat mass were positively associated with BMD Z-scores. 25-OHD level was positively associated with BMD Z-scores, even after adjusting for other factors. This study suggests that vitamin D level is positively associated with BMD in adolescents; therefore, maintaining sufficient vitamin D levels during adolescence is crucial to prevent low BMD.