Kwiterovich P O
Johns Hopkins University School of Medicine, Department of Pediatrics and Medicine, Baltimore, MD 21287-3654, USA.
J Am Diet Assoc. 1997 Jul;97(7 Suppl):S31-41. doi: 10.1016/s0002-8223(97)00727-x.
A number of primary and secondary prevention trials, including angiographic studies, have indicated that a decrease in dietary saturated fat and cholesterol produces a decrease in the blood levels of cholesterol and low-density lipoprotein (LDL) cholesterol, leading to a decrease in coronary artery disease (CAD). Increasing evidence indicates that the oxidation of LDL in human beings is atherogenic. Of the three major antioxidants, vitamin E, beta carotene, and vitamin C, the evidence is strongest that vitamin E (at a minimum dose of 100 IU/day) has a strong and independent inverse association with CAD. Selenium and flavonoids also have antioxidant properties, but their association with CAD in human beings is equivocal. Two prooxidants, homocysteine and iron, have been found to be associated with CAD. Blood homocysteine levels can be lowered significantly by an increase in dietary folic acid. Clinical trials are needed to assess expeditiously the effect of antioxidants, particularly vitamin E, and of folic acid on CAD and atherosclerosis. The substitution of monounsaturated fat for saturated fat lowers LDL and makes it less susceptible to oxidation without decreasing high-density lipoprotein (HDL) cholesterol. Studies in transgenic mice indicate that apolipoprotein A-I, the major protein of HDL, may inhibit the oxidation of LDL. Dietary trans fatty acids at the level consumed by many Americans can increase LDL cholesterol and may decrease HDL cholesterol. Individuals who have CAD or have family members who have premature CAD have delayed clearance of dietary fat, as judged by studies of postprandial triglyceride metabolism. The importance of decreasing dietary saturated fat and cholesterol is well established, but a number of other factors appear to influence the risk of CAD significantly and provide important areas for future investigation to improve prevention and treatment through better nutrition.
包括血管造影研究在内的多项一级和二级预防试验表明，饮食中饱和脂肪和胆固醇的减少会导致血液中胆固醇和低密度脂蛋白（LDL）胆固醇水平降低，从而使冠状动脉疾病（CAD）减少。越来越多的证据表明，人体内低密度脂蛋白的氧化具有致动脉粥样硬化作用。在三种主要抗氧化剂维生素E、β-胡萝卜素和维生素C中，证据最充分的是维生素E（最低剂量为100国际单位/天）与CAD存在强烈且独立的负相关。硒和类黄酮也具有抗氧化特性，但它们与人类CAD的关联尚不明确。已发现两种促氧化剂同型半胱氨酸和铁与CAD有关。通过增加饮食中的叶酸可以显著降低血液中的同型半胱氨酸水平。需要进行临床试验，以便迅速评估抗氧化剂，特别是维生素E，以及叶酸对CAD和动脉粥样硬化的影响。用单不饱和脂肪替代饱和脂肪可降低LDL，并使其不易被氧化，同时不会降低高密度脂蛋白（HDL）胆固醇。对转基因小鼠的研究表明，HDL的主要蛋白质载脂蛋白A-I可能抑制LDL的氧化。许多美国人所摄入水平的膳食反式脂肪酸会增加LDL胆固醇，并可能降低HDL胆固醇。根据餐后甘油三酯代谢研究判断，患有CAD或有CAD家族史的个体清除膳食脂肪的速度较慢。减少饮食中饱和脂肪和胆固醇的重要性已得到充分证实，但许多其他因素似乎也会显著影响CAD风险，并为未来通过更好的营养改善预防和治疗提供重要的研究领域。
