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，但替代饱和脂肪（碳水化合物、蛋白质或不饱和脂肪）的常量营养素类型是一个重大的、尚未解决的研究问题，具有重大的公共卫生影响。拟议的研究将通过研究这三种饮食方式对已确定的冠状动脉危险因素和一组选定的新出现的危险因素的影响来评估它们。该研究设计是一项随机、三期交叉喂养研究，将比较富含碳水化合物的饮食（DASH饮食）与另外两种饮食（一种富含蛋白质，另一种富含不饱和脂肪，主要是单不饱和脂肪）对血压和血脂的影响。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，目前被政策制定者推荐。在为期一周的磨合中，所有参与者将被喂食3种研究饮食（DASH， PROTEIN和UNSAT）的样本。采用三期交叉设计，参与者将被随机分配到DASH，蛋白质或UNSAT饮食。每期饲喂6周；每个喂养期至少有2周的洗脱期。在整个喂食过程中（磨合期和3个干预期），参与者将被喂食足够的卡路里来维持体重。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，收缩压为120-159 mmHg，舒张压为80-95 mmHg。主要结局变量为血压和已确定的血脂危险因素（LDL-C、HDL-C和甘油三酯）。次要结局包括载脂蛋白VLDL-apoB和VLDL-apoCIII，它们应该优于甘油三酯作为心血管事件的预测因子，以及总载脂蛋白B、非高密度脂蛋白胆固醇和脂蛋白(a)。在这种情况下，该试验应该提高我们对饮食对传统和新兴风险因素影响的基本认识，并在此过程中，告知政策制定者和卫生保健提供者碳水化合物、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手段的相对益处。

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.