Macronutrients and Cardiovascular Risk

虽然人们普遍认为，降低心血管风险的最佳饮食应该是低饱和脂肪，但应该用什么类型的大量营养素来取代饱和脂肪(碳水化合物、蛋白质或不饱和脂肪)是一个重大的、尚未解决的研究问题，对公共健康具有重大影响。这项拟议的研究将通过研究它们对已确立的冠状动脉危险因素和选定的一组新出现的危险因素的影响来评估这三种饮食方法。这项研究设计是一项随机的、三个阶段的交叉喂养研究，将富含碳水化合物的饮食(DASH饮食)与另外两种饮食对血压和血脂的影响进行比较，一种是富含蛋白质的饮食，另一种是富含不饱和脂肪(UNSAT)的饮食，主要是单不饱和脂肪。DASH饮食已被证明可以显著降低血压和低密度脂蛋白-胆固醇，目前正被政策制定者推荐。在为期一周的试运行期间，所有参与者都将获得3种研究饮食(DASH、蛋白质和UNSAT)的样本。采用三阶段交叉设计，参与者将被随机分配到DASH、蛋白质或UNSAT饮食中。每个喂食期将持续6周；每个喂食期将分开至少2周的冲洗期。在整个喂养过程中(磨合和3个干预期)，参与者将获得足够的卡路里来维持他们的体重。试验参与者(n=200，约50%为女性，约50%为非裔美国人)年龄在20岁或以上，收缩压在120-159毫米汞柱，舒张压在80-95毫米汞柱。主要结果变量将是血压和已确定的血脂风险因素(低密度脂蛋白、高密度脂蛋白胆固醇和甘油三酯)。次要结果将包括载脂蛋白VLDL-apoB和VLDL-apoCIII，它们作为心血管事件的预测指标应该优于甘油三酯，以及总载脂蛋白B、非高密度脂蛋白胆固醇和脂蛋白(A)。通过这种方式，试验应该促进我们对饮食对传统和新出现的风险因素的影响的基础知识，并在这个过程中，让政策制定者和医疗保健提供者了解碳水化合物、蛋白质和不饱和脂肪(主要是单不饱和脂肪)作为降低心血管风险的手段的相对好处。

While there is widespread consensus that the optimal diet to reduce cardiovascular risk should be low in saturated fat, the type of macronutrient that should replace saturated fat (carbohydrate, protein or unsaturated fat) is a major, unresolved research question with substantial public health implications. The proposed study will evaluate these 3 dietary approaches by studying their effects on established coronary risk factors and a selected group of emerging risk factors. The study design is a randomized, three period cross-over feeding study that will compare the effects on blood pressure and plasma lipids of a carbohydrate-rich diet (the DASH diet) to two other diets, one rich in protein and another rich in unsaturated (UNSAT) fat, predominantly monounsaturated fat. The DASH diet has been shown to reduce blood pressure and LDL-cholesterol substantially, and is currently recommended by policy makers. During a 1 week run- in, all participants will be fed samples of the 3 study diets (DASH, PROTEIN and UNSAT). Using a three period cross-over design, participants will then be randomly assigned to the DASH, PROTEIN OR UNSAT diet. Each feeding period will last 6 weeks; a washout period of at least 2 weeks will separate each feeding period. Throughout feeding (run-in and the 3 intervention periods), participants will be fed sufficient calories to maintain their weight. Trial participants (n=200, approximately 50 percent female, approximately 50 percent African-American) will be 20 years of age or older, with systolic blood pressure of 120-159 mmHg and diastolic blood pressure of 80-95 mmHg. Primary outcomes variables will be blood pressure and the established plasma lipid risk factors (LDL-C, HDL-C and triglycerides). Secondary outcomes will include apolipoproteins VLDL-apoB and VLDL-apoCIII, which should be superior to triglycerides as predictors of cardiovascular events, as well as total apolipoprotein B, non-HDL cholesterol, and lipoprotein(a). In this fashion, the trial should advance our fundamental knowledge of the effects of diet on both traditional and emerging risk factors, and in the process, inform policy makers and health care providers on the relative benefits of carbohydrate, protein and unsaturated fat, predominantly monounsaturated fat, as means to reduce cardiovascular risk.