Correlates of vitamin D deficiency in a multiracial United States adolescent population: The National Health and Nutrition Examination Survey III

BACKGROUND Vitamin D deficiency has been linked to many chronic diseases. There is a lack of consensus as to optimal vitamin D status. Currently, vitamin D deficiency is defined as a serum 25(OH)D level below 11 ng/ml. Over 300 experts collectively proposed that minimum serum levels be 20 ng/ml. OBJECTIVE 1) Determine the prevalence of vitamin D deficiency in adolescents using the current and recommended cutoffs. 2) Examine the implications of the new recommendation after adjustment for various factors. METHODS Data were obtained from NHANES III, 1988-94, which is a cross-sectional survey administered to a nationally representative sample aged 2 months and older. Analyses included 2,955 participants aged 12-19 with serum 25(OH)D levels. Relationships between vitamin D deficiency and selected variables were evaluated. RESULTS Changing the definition of vitamin D deficiency to <20 ng/ml from <11 ng/ml resulted in an increase in prevalence from 2% to 14%. After adjustment for all covariates, Non-Hispanic Blacks had a 20.3 times increased odds of serum 25(OH)D < 20ng/ml than Non-Hispanic Whites (95% CI 11.7-35.3). Females had a 2.7 times increased odds of vitamin D deficiency compared to males (95% CI 1.9-3.9). Overweight adolescents had almost twice the odds of vitamin D deficiency compared to normal weight adolescents (95% CI 1.3-3.1). CONCLUSIONS Vitamin D deficiency disproportionately affects Non-Hispanic Black adolescents. Routine supplementation and monitoring of serum levels should be considered. There is an inverse relationship between obesity and vitamin D deficiency. The consequences of chronic vitamin D deficiency in adolescents should be explored prospectively.