Department of Foods and Nutrition, Purdue University, West Lafayette, IN, USA.
J Bone Miner Res. 2010 Aug;25(8):1842-9. doi: 10.1002/jbmr.76.
Calcium requirements of North American adolescents were set at 1300 mg/day based on data from white girls. Calcium requirements for Asian-American adolescents have not been studied. Using metabolic balance protocols and a range in calcium intakes, skeletal calcium retention was determined in Chinese-American adolescents. A sample of 29 adolescents, 15 boys aged 12 to 15 years and 14 girls aged 11 to 15 years, was studied twice on paired calcium intakes ranging between 629 to 1835 mg/day using a randomized-order crossover design. Calcium absorption and bone turnover rates using double-stable calcium isotope kinetic analysis on two calcium intakes per subject were measured and compared in boys and girls. Girls and boys had low habitual mean calcium intakes of 648 and 666 mg/day, respectively, and low mean serum 25-hydroxyvitamin D concentrations of 19.1 and 22.2 ng/mL, respectively. True fractional calcium absorption varied inversely with calcium load. Boys had significantly higher bone turnover rate than girls at the same calcium intake. Calcium retention increased with calcium intake; calcium intakes to achieve maximal calcium retention were 1100 mg/day in boys and 970 mg/day in girls. Recommendations for calcium requirements should be lowered for Chinese-American adolescents.
基于白人女孩的数据，北美青少年的钙需求量被设定为 1300 毫克/天。尚未研究亚裔美国青少年的钙需求量。本研究使用代谢平衡方案和一系列钙摄入量，在华裔美国青少年中确定了骨骼钙保留率。研究了 29 名青少年，其中 15 名男孩年龄在 12 至 15 岁之间，14 名女孩年龄在 11 至 15 岁之间，采用随机交叉设计，两次分别在 629 至 1835 毫克/天的范围内进行配对钙摄入量。通过对每个受试者的两种钙摄入量进行双稳定钙同位素动力学分析，测量并比较了男孩和女孩的钙吸收和骨转换率。女孩和男孩的习惯性平均钙摄入量分别为 648 和 666 毫克/天，平均血清 25-羟维生素 D 浓度分别为 19.1 和 22.2 纳克/毫升。真正的钙吸收分数与钙负荷呈反比变化。在相同的钙摄入量下，男孩的骨转换率明显高于女孩。钙保留随着钙摄入量的增加而增加；达到最大钙保留的钙摄入量分别为男孩 1100 毫克/天和女孩 970 毫克/天。应降低华裔美国青少年的钙需求量建议。
