Background: A number of studies have investigated the relationship between 25-hydroxyvitamin D (25-OH-D) and bone mineral density (BMD) during childhood. However, there is considerable variation in study subjects, geographic location, season in which the study is conducted, and confounding factors considered. Consequently, reported relationships between 25-OH-D and BMD have been somewhat inconsistent. There remains a substantial shortage of information concerning the Japanese child population. In the present study, we investigated the relationship between serum 25-OH-D concentration and whole body BMD among Japanese children.
Methods: The source population was all fifth-grade students (521 children) attending two public elementary schools in Hamamatsu, Japan. Among these, we obtained cross-sectional data from 401 children (mean age, 11.2 years) in November and December. Whole body bone mineral content (BMC) and whole body BMD were measured using a single dual-energy X-ray absorptiometry scanner. In addition, a non-fasting blood specimen was collected from each subject. Serum 25-OH-D concentration was measured by a radioimmunoassay. This study was approved by the Ethics Committee of our university.
Results: Boys showed positive relationships between serum 25-OH-D concentration and whole body BMD and BMC after adjusting for confounding factors, such as height, weight, and pubic hair appearance (BMD, β=0.20; BMC, β=0.09; P < 0.05 for each value). Girls showed a positive relationship between serum 25-OH-D concentration and whole body BMD after adjusting for confounding factors (β=0.13, P < 0.05).
Conclusion: A high serum vitamin D concentration was associated with good bone health in a population of Japanese school children.
Disclosure: The authors declared no competing interests. This work was supported by Grants-in-Aid for Scientific Research (#21657068 and #22370092) from the Japan Society for the Promotion of Science.