DIETARY CALCIUM AND PREVENTION OF HYPERTENSION IN BLACKS

来自动脉高血压动物模型的证据表明， 膳食钙对血压的影响。 然而，在这方面， 在人类中进行的流行病学和临床研究产生了不同的结果。 对这一文献的回顾表明， 膳食钙和血压在美国黑人和青年中最为明显， 在成年白人中它很小或不存在。对...的合理解释 这种发现模式是膳食钙对血压的影响， 发生在生命周期的早期。 因此，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后（这与他的下降是一致的）。 在这一人群中的乳制品消费）。 为了设定这一假设，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筛查血压升高的学生（N = 100） 计划将随机分配至8周钙补充（1500 mg/d） 和安慰剂条件在秋季学期。 交叉将 发生在春季学期。 补充剂将由 学校护士允许精确的剂量测量。 影响 钙补充将通过SBP和DBP的变化进行评估 通过标准和流动方法测量。 在第二年和第三年， 研究，这些学生留在学校将评估为 第1年观察到的表观钙敏感性的重现性， 2. 甲状旁腺激素血浆浓度的同时变化， 将测量总钙和离子钙以及BP的其他相关性。 如果钙补充剂成功地降低了与年龄相关的血压， 这一人口的增加，那么健康保护政策的目的是 经常摄入的食物中补充钙可以改善一些 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.