Search for promotion factors of ultrasound bone measurement in Japanese males and pre/post-menarcheal females aged 8-14 years.

There is little evidence regarding the associations between bone growth and environmental factors among growing children, especially in Asians. The aim of this cross-sectional study was to search for the promotion factors of bone growth in Japanese children during growth. The study subjects were male (n=333) and pre/post-menarcheal female (n=179/n=68) school children aged 8-14 y. Bone status at the calcaneus was evaluated by quantitative ultrasound (Benus III), and the bone area ratio (BAR) was used as an evaluation index. Dietary intakes were assessed via brief self-administered diet history questionnaires. The participants were asked to record all of their activities for 3 d (2 weekdays and 1 holiday). They were also required to provide the most recent anthropometric measurement records at their schools and answer questions about the frequency of fractures and, for females, the length of time since menarche. Multiple regression analysis with dummy variables demonstrated that age, magnesium (more than the RDA), vitamin B(1) (more than the RDA), mean physical activity intensity per day (more than 1.7 METs), vitamin C (more than the RDA) and calcium (more than the RDA) were significantly positive influential factors of BAR for males. For premenarcheal females, age, vitamin A (more than the RDA), BMI, and mean physical activity intensity per day (more than 1.7 METs) were significantly positive influential factors of BAR, and for postmenarcheal females, only BMI and age were significantly positive influential factors of BAR. The results suggest that several manageable factors correlate with the bone mass, and the associations differ depending on gender and menarcheal status.