FOLIC ACID INTAKE & HOMOCYSTEINE--A DOSE RESPONSE STUDY

描述：（改编自研究者摘要）长期目的 这项研究的目的是提供可靠的信息， 心血管获益可能来自不同的治疗策略， 增加人群的叶酸摄入量。 这些战略包括： 通过增加每日水果的摄入量来改变叶酸的饮食摄入量， 蔬菜，可能导致每天增加相当于50微克叶酸 叶酸;添加含有叶酸的常规膳食补充剂， 导致每天增加400微克叶酸; 强化面粉和谷物制品，含量为140微克/100克 产品，可能导致叶酸的每日平均增加 在50微克和160微克之间。 这项双盲研究的具体目的是 描述叶酸变化与 血浆同型半胱氨酸对叶酸摄入量的适度变化。 具体 假设检验与叶酸相关的同型半胱氨酸水平差异 不同剂量的酸干预：1.400 ug cf. 50 ug; 2. 400 ug cf. 160微克; 3. 160 ug cf. 0 μ g。 将筛选志愿者的基因型， 亚甲基四氢叶酸还原酶变异体，以及 同型半胱氨酸 在基因型、性别和广泛同型半胱氨酸水平内， 志愿者将首先登记。 因为假设的 提高黑人同型半胱氨酸代谢的效率， 非裔美国人志愿者将被招募，以允许单独估计 剂量反应曲线 预计共有160名志愿者 成功完成磨合，他们将被分配，使用拉丁语 正方形设计，随机接受5次叶酸治疗，每次 持续6周：安慰剂、50 ug、160 ug、400 ug和650 ug叶酸。 每个治疗阶段之间将有6周的洗脱期。 将在基线和基线时采集空腹静脉穿刺血样。 每个治疗阶段结束时，分析同型半胱氨酸，红细胞叶酸， 血浆叶酸和血浆B12。 将比较对同型半胱氨酸的影响 将估计每种治疗之间的剂量-反应曲线， 性别和广泛的同型半胱氨酸组（分别对于非洲裔美国人， 每个性别和广泛的同型半胱氨酸水平）。 潜力估计 心血管益处将通过整合这一结果来计算。 拟议的研究与荟萃分析的研究之间的关系 同型半胱氨酸和心血管疾病风险。

DESCRIPTION: (Adapted from Investigator's Abstract) The long-term objective of this study is to provide reliable information concerning the cardiovascular benefit likely to accrue from different strategies for increasing folic acid intake of the population. The strategies include: changing dietary intake of folate by increasing daily servings of fruits and vegetables, likely to result in a daily increase equivalent to 50 ug folic acid; adding a regular dietary supplement containing folic acid, likely to result in a daily increase of 400 ug folic acid; and fortification of enriched flour and cereal grain products at the level of 140 ug/100 g product, likely to result in a daily average increase in folic acid of between 50 ug and 160 ug. The specific aim of this double-blind study is to characterize the relationship between change in folic acid and change in plasma homocysteine for modest changes in folic add intake. The specific hypotheses test differences in homocysteine levels associated with folic acid interventions at different doses: 1.400 ug cf. 50 ug; 2. 400 ug cf. 160 ug; 3. 160 ug cf. 0 ug. Volunteers will be screened for genotype of methylenetetrahydrofolate reductase variant, and casual level of homocysteine. Within genotype, gender and broad homocysteine level, 150 volunteers will be enrolled initially. Because of the hypothesized increased efficiency of homocysteine metabolism in blacks, an additional 50 African American volunteers will be enrolled to allow separate estimates of the dose-response curve. In all, 160 volunteers are expected to successfully complete the run-in and they will be assigned, using a Latin Square design, to receive five folic acid treatments in random order, each lasting six weeks: placebo, 5O ug, 160 ug, 400 ug, and 650 ug folic acid. There will be washout periods of six weeks between each treatment phase. Fasting venipuncture blood samples will be obtained at baseline and at the end of each treatment phase, and analyzed for homocysteine, red cell folate, plasma folate and plasma B12. Effects on homocysteine will be compared between each treatment, and dose-response curves will be estimated for each gender and broad homocysteine group (and separately for African Americans, for each gender and broad homocysteine level). Estimates of potential cardiovascular benefit will be calculated by integrating the results of this proposed study with a meta-analysis of studies of the relationship between homocysteine and risk of cardiovascular disease.