Calcium Metabolism in Mexican American Adolescents

描述(由申请者提供)：我们发现青少年在钙滞留和动力学方面存在显著的种族和性别差异。美国黑人女孩比白人女孩在目前推荐的钙摄入量下有更大的钙滞留(481 mg/d比282 mg/d)，这是因为更高的净骨形成率，更高的钙吸收和更低的尿钙排泄。我们还发现，在所有的钙摄入量中，白人男孩比女孩保留更多的钙。从这些平衡和动力学研究中，我们建立了钙摄入量和钙保留量之间的关系模型，可以用来估计青少年骨骼最大吸收所需的钙。我们目前正在研究华裔美国青少年中的这些关系。中国男孩和女孩在所有钙的摄入量上都比白人男孩和女孩有更大的钙储留量。在这份申请中，我们建议研究墨西哥裔美国少数民族的青少年男孩和女孩之间的这些关系，他们是拉美裔美国人中最大的群体，不久将占美国人口的四分之一。我们假设，与其他少数族裔群体一样，墨西哥裔美国人对钙摄入量的反应与白人青少年相比，在低钙摄入量时钙吸收效率更高。第一个目标是确定墨西哥裔美国女孩和男孩的钙需求量；第二个目标是确定钙摄入量和钙吸收分数之间的关系；第三个目标是确定墨西哥裔美国青少年中肠道、肾脏和骨骼对钙保持的相对贡献，并将这些结果与美国白人、黑人和亚洲青少年中已经确定的结果进行比较；第四个目标是建立一个模型，量化钙摄入量、种族/民族、性别和性成熟对钙保持的影响。正如我们在之前的研究中所做的那样，我们将使用稳定的钙同位素动力学结合代谢平衡研究作为夏季研究夏令营。优化美国多数和少数群体在青春期的钙滞留是建立美国老年人口骨量峰值和降低终身骨质疏松风险的关键营养策略。与公共健康相关：拉美裔很快将占美国人口的四分之一。该项目将确定饮食钙在墨西哥裔美国青少年骨骼钙滞留中的作用，并将这些结果与我们在其他种族群体中发现的结果进行比较，以确定导致种族差异的机制。这些研究将使我们能够确定在骨骼快速生长期间保持最佳钙含量所需的钙摄入量，这是建立峰值骨量和降低终身骨质疏松风险的关键营养策略。

DESCRIPTION (provided by applicant): We have found significant racial and sex differences in calcium retention and kinetics in adolescents. American black girls had greater calcium retention than white girls (481 vs. 282 mg/d) on current recommended calcium intake as a result of greater net bone formation rates, higher calcium absorption and lower urinary calcium excretion. We also found white boys retain more calcium than girls at all calcium intakes. From these balance and kinetic studies, we have developed a model of the relationship between calcium intake and calcium retention that can be used to estimate calcium requirements for maximal skeletal accretion in adolescents. We are currently studying these relationships in Chinese American adolescents. Chinese boys and girls have greater calcium retention at all calcium intakes than white boys and girls. In this application, we propose to study these relationships in adolescent boys and girls from the Mexican American minority who are the largest group of Hispanics and will soon comprise one-fourth of the U.S. population. We hypothesize that Mexican Americans respond to calcium intake like other minority groups with increased calcium absorption efficiency at low calcium intakes in comparison to white adolescents. The first aim is to establish the calcium requirement in Mexican American girls and boys; the second aim is to establish the relationship between calcium intake and fractional calcium absorption; the third aim is to determine the relative contribution of the intestine, kidney, and bone to calcium retention in Mexican American adolescents and compare these results with those already established in American white, black, and Asian adolescents; and the fourth aim is to develop a model to quantify the effect of calcium intake, race/ethnic group, sex, and sexual maturity on calcium retention. As we have done in our previous studies, we will use stable calcium isotope kinetics coupled with metabolic balance studies conducted as a summer research camp. Optimizing calcium retention during adolescence in both majority and minority populations in the U.S. is a key nutritional strategy to build peak bone mass and reduce lifelong risk of osteoporosis in the elderly U.S. population. PUBLIC HEALTH RELEVANCE: Hispanics will soon comprise one-fourth of the U.S. population. This project will determine the role of dietary calcium in skeletal calcium retention in Mexican American adolescents and will compare these results with what we have found in other racial groups to identify mechanisms responsible for the racial differences. These studies will allow us to determine the calcium intake required for optimal calcium retention during the period of rapid skeletal growth which is a key nutritional strategy to build peak bone mass and reduce lifelong risk of osteoporosis.