25-Hydroxyvitamin D, Calcium Intake, and Bone Mineral Content in Adolescents and Young Adults: Analysis of the Fourth and Fifth Korea National Health and Nutrition Examination Survey (KNHANES IV-2, 3, 2008-2009 and V-1, 2010)

Context: The amount of calcium and vitamin D needed to support bone development is still uncertain. Objective: We examined the association of 25-hydroxyvitamin D [25(OH)D] and calcium intake with bone mineral content (BMC). Design: A total of 2918 subjects (1345 males and 1573 females) aged 10 to 29 years from the 2008-2010 Korea National Health and Nutrition Examination Survey were stratified into 3 age groups: early adolescents, late adolescents, and young adults. Outcome Measures: BMC of femoral neck, total hip, and lumbar spine were evaluated in each group according to quartiles of serum 25(OH)D concentration and calcium intake. Results: Mean serum 25(OH)D for all males and females were 43.4 and 39.2 nmol/L, and calcium intakes were 524.4 and 437.2 mg/d, respectively. Early adolescent and young adult males had strong and significant associations of serum 25(OH)D with BMC at each skeletal site. The association was not linear, and a step up was observed at a 25(OH)D concentration of 53.0 nmol/L. Although the impact of calcium intake on BMC was not evident, the top quartile of both serum 25(OH)D and calcium intake had a higher BMC than those in the top quartile of either nutrient alone in these subjects. In late adolescent males and in females, 25(OH)D and BMC associations were inconsistent. Conclusions: This cross-sectional study indicates a significant association of serum 25(OH)D concentration with BMC and a supportive role of calcium on bone mass for early adolescents and young adult males. We believe that a large proportion of young Koreans would attain greater BMC if they increased their 25(OH)D concentrations and calcium intake. (J Clin Endocrinol Metab 98: 3627-3636, 2013)