Braun Michelle, Martin Berdine R, Kern Mark, McCabe George P, Peacock Munro, Jiang Zhen, Weaver Connie M
Purdue University, West Lafayette, IN, USA.
Am J Clin Nutr. 2006 Aug;84(2):414-8. doi: 10.1093/ajcn/84.1.414.
National calcium requirements in the United States for boys are based on data from girls. On average, boys develop larger skeletons than do girls, yet it is unknown whether the additional skeletal accretion in boys requires additional dietary calcium intake.
The objective was to determine calcium retention in adolescent boys in response to a range of controlled intakes and to compare the intake needed for maximal retention in boys with that needed in adolescent girls studied under the same conditions.
Thirty-one boys aged 12-15 y participated in 3-wk metabolic balance studies testing a range (700-2100 mg/d) of calcium intakes in a crossover study design with a 2-wk washout period. Calcium intake was varied by using a beverage fortified with calcium citrate malate. After a 1-wk equilibration period, calcium retention was calculated as dietary calcium intake minus the calcium excreted in the feces and urine over the following 2 wk. The dietary intake at which maximal calcium retention occurred was determined by using a nonlinear regression model. The results in boys were compared with those obtained in 35 adolescent girls previously studied under the same protocol.
Maximal calcium retention in boys was achieved at an intake of 1140 mg/d. Calcium retention was higher (by 171 +/- 38 mg/d) in boys than in girls at all calcium intakes studied.
The higher calcium retention in boys than in girls was attained through higher net calcium absorption and lower urinary excretion than in girls.
美国男孩的国家钙需求量是基于女孩的数据制定的。平均而言，男孩的骨骼比女孩的更大，但尚不清楚男孩额外的骨骼生长是否需要额外的膳食钙摄入量。
目的是确定青少年男孩在一系列受控摄入量下的钙潴留情况，并将男孩达到最大钙潴留所需的摄入量与在相同条件下研究的青少年女孩所需的摄入量进行比较。
31名12 - 15岁的男孩参与了为期3周的代谢平衡研究，采用交叉研究设计，测试一系列（700 - 2100毫克/天）的钙摄入量，有2周的洗脱期。通过使用添加了苹果酸钙的饮料来改变钙摄入量。经过1周的平衡期后，钙潴留量计算为膳食钙摄入量减去接下来2周粪便和尿液中排出的钙量。通过非线性回归模型确定出现最大钙潴留时的膳食摄入量。将男孩的结果与之前按照相同方案研究的35名青少年女孩的结果进行比较。
男孩在摄入量为1140毫克/天时达到最大钙潴留。在所有研究的钙摄入量下，男孩的钙潴留量均高于女孩（高出171±38毫克/天）。
与女孩相比，男孩较高的钙潴留是通过比女孩更高的净钙吸收和更低的尿钙排泄实现的。
