Zhu Kun, Greenfield Heather, Zhang Qian, Du Xueqin, Ma Guansheng, Foo Leng Huat, Cowell Chris T, Fraser David R
Faculty of Veterinary Science, University of Sydney, Sydney, Australia.
J Bone Miner Res. 2008 Feb;23(2):167-72. doi: 10.1359/jbmr.071006.
There are few longitudinal data on bone development during puberty in children with low calcium intake. This 5-yr longitudinal study showed that, in Chinese girls, the mean apparent calcium retention efficiency during puberty was 40.9%, PHV occurred at 3-0 yr before menarche, and peak bone mineral accretion occurred 1 yr later than PHV. Chinese girls have high calcium retention efficiency during puberty.
There are few longitudinal data on bone development during puberty in children with low dietary calcium intake. The aim of this study was to examine the rate of growth and bone mineral accretion and study the predictors of total body BMC during puberty in a 5-yr longitudinal study with Chinese girls.
Ninety-two girls, 9.5-10.5 yr of age at baseline, from the unsupplemented control group of a school milk intervention trial were included in this analysis. Data on anthropometric measurements, total body BMC as assessed by DXA, and calcium intake as assessed by a 3-day food record were obtained at baseline and 1, 2, 4, and 5 yr.
The mean age of menarche was 12.1 +/- 1.0 yr. The mean annual rate of bone mineral accretion was 197.4 g/yr during the follow-up period, representing a calcium accretion rate of 162.3 mg/d. This calcium retention rate and the average dietary calcium intake of 444.1 mg/d gave an apparent calcium retention efficiency of 40.9%. Peak height velocity (PHV) occurred at 3-0 yr before menarche. Peak bone mineral accretion occurred 1 yr later than PHV. There was a decrease in size-corrected BMD in the year before menarche. In the linear mixed-effects model analysis containing body size and lifestyle factors, we found that height, body weight, and calcium intake were significant independent predictors of total body BMC.
Chinese girls with low habitual dietary calcium intake have high calcium retention efficiency during puberty. Because calcium intake is a significant predictor of total body BMC, increasing dietary calcium intake may have beneficial effects on bone mineral accretion in these girls.
关于钙摄入量低的儿童青春期骨骼发育的纵向数据较少。这项为期5年的纵向研究表明，中国女孩在青春期的平均表观钙保留效率为40.9%，身高突增高峰（PHV）发生在初潮前3.0年，峰值骨量增加发生在PHV后1年。中国女孩在青春期有较高的钙保留效率。
关于饮食钙摄入量低的儿童青春期骨骼发育的纵向数据较少。本研究的目的是在一项针对中国女孩的为期5年的纵向研究中，检查生长速率和骨量增加情况，并研究青春期全身骨量（BMC）的预测因素。
本分析纳入了一项学校牛奶干预试验未补充组中92名基线年龄为9.5 - 10.5岁的女孩。在基线、第1、2、4和5年获取了人体测量数据、通过双能X线吸收法（DXA）评估的全身BMC以及通过3天食物记录评估的钙摄入量。
初潮的平均年龄为12.1±1.0岁。随访期间骨量增加的平均年速率为197.4 g/年，相当于钙增加速率为162.3 mg/天。该钙保留率和平均每日饮食钙摄入量444.1 mg/天得出表观钙保留效率为40.9%。身高突增高峰（PHV）发生在初潮前3.0年。峰值骨量增加发生在PHV后1年。初潮前一年经大小校正的骨密度（BMD）有所下降。在包含身体大小和生活方式因素的线性混合效应模型分析中，我们发现身高、体重和钙摄入量是全身BMC的显著独立预测因素。
习惯性饮食钙摄入量低的中国女孩在青春期有较高的钙保留效率。由于钙摄入量是全身BMC的显著预测因素，增加饮食钙摄入量可能对这些女孩的骨量增加有有益影响。
