Gender-Dependent Skeletal Effects of Vitamin D Deficiency in a Younger Generation

Context: The major health threats caused by vitamin D deficiency in the young generation have not been fully elucidated. Objective: The aim of this study was to investigate skeletal and nonskeletal effects of vitamin D deficiency and to study the optimal level of serum 25-hydroxyvitamin D [25(OH)D] in young people. Design and Setting: The Fourth Korea National Health and Nutrition Examination Surveys (KNHANES IV) was conducted in 2008–2009. Participants: A total of 4276 people (1926 men and 2350 women) aged 10–40 yr were selected from 16 administrative districts of South Korea. Main Outcome Measures: We measured age-specific changes in bone mineral density (BMD) according to serum 25(OH)D. Results: Serum 25(OH)D was less than 25 nmol/liter in 18.8% of participants, 25 to less than 50 nmol/liter in 50.0%, 50 to less than 75 nmol/liter in 27.0%, and 75 nmol/liter or greater in 4.2%. Vitamin D deficiency was more frequent in women than in men. There were gender differences in the skeletal effects of vitamin D deficiency. In men between 10 and 22 yr old, BMD was significantly higher in the vitamin D-sufficient group, and in men between 23 and 40 yr old, a positive correlation between serum 25(OH)D and BMD was observed. However, in women, we could not find significant differences in BMD according to vitamin D status. Vitamin D deficiency in younger generations had no remarkable effects on most nonskeletal parameters or on the prevalence of concomitant diseases except for rheumatoid arthritis. Conclusions: Vitamin D plays an essential role in skeletal health of young people. Moreover, the presence of gender-dependent skeletal effects was an important observation of this study. Reassurance of serum 25(OH)D up to 20–30 ng/ml or higher is necessary, especially during the modeling phase in men.