DIETARY CALCIUM AND PREVENTION OF HYPERTENSION IN BLACKS

来自动脉高血压动物模型的证据表明 膳食钙对血压的降压作用。然而， 在人类身上进行的流行病学和临床研究产生了好坏参半的结果。 对这篇文献的回顾表明， 饮食中的钙和血压在美国黑人和年轻人中最为明显，而 在成年白人中，这种情况很少或根本不存在。一个貌似合理的解释 这一发现模式是饮食中钙对血压的影响 发生在生命周期的早期。因此，可以假设饮食 在黑人青年中补充钙将减缓血压的上升 发生在美国黑人的青春期之后(这与他的衰退不谋而合 在这一人群中的乳制品消费)。 为了把这个假设设为双盲、交叉、安慰剂 建议在黑人青少年中进行对照试验。高中 在持续的血压监测中对学生进行血压升高筛查(N=100) 计划将随机进行8周的补钙(1500毫克/天) 以及秋季学期的安慰剂条件。交叉遗嘱 发生在春季学期。补充剂将由以下人员管理 学校护士允许精确的剂量测量。的影响。 补钙将通过SBP和DBP的变化来评估 用标准的和非标准的方法测量。在第二年和第三年 学习，那些留在学校的学生将被评估 在第一年和第二年观察到的表观钙敏感性的重复性 2.甲状旁腺激素的血浆浓度同时变化， 测量血压的总钙、离子钙及其他相关指标。 补钙是否能成功钝化年龄相关性BP 这一人口的增长，那么健康保护政策旨在 经常摄入的食物补钙可以改善某些症状 美国黑人患高血压的风险过高。

Evidence from animal models of arterial hypertension suggests a hypotensive effect of dietary calcium on blood pressure (BP). However, epidemiologic and clinical studies in humans have yielded mixed results. A review of this literature indicates that an inverse relation between dietary calcium and BP is most evident among US blacks and youth, while it is small or absent among adult whites. A plausible explanation of this pattern of findings is that the effect of dietary calcium on BP occurs early in the life cycle. Thus, it is hypothesized that dietary calcium supplementation among black youth will blunt the rise in BP that occurs after puberty in US blacks (which is coincident with he decline in consumption of dairy products in this population). In order to set this hypothesis a double blind, cross over, placebo controlled trial among black adolescents is proposed. High school students screened for elevated BP (N=100) in an ongoing BP monitoring program will be randomized to 8 week calcium supplementation (1500 mg/d) and placebo conditions during the Fall school semester. Cross-over will occur during the Spring semester. Supplements will be administered by school nurses to allow precise dosage measurement. Effects of the calcium supplementation will be assessed by change in SBP and DBP measured by standard and ambulatory methods. In Years 2 and 3 of the study, those students remaining in the school will be assessed for the reproducibility of apparent calcium sensitivity observed in Years 1 and 2. Concurrent changes in plasma concentrations of parathyroid hormone, total and ionized calcium, and other correlates of BP will be measured. If calcium supplementation is successful in blunting the age related BP rise in this population, then health protective policies aimed at calcium supplementation of commonly ingested foods could ameliorate some of the excess risk of hypertension among US blacks.