Connor W E, DeFrancesco C A, Connor S L
Department of Medicine, Oregon Health Sciences University, Portland 97201-3098.
Ann N Y Acad Sci. 1993 Jun 14;683:16-34. doi: 10.1111/j.1749-6632.1993.tb35689.x.
In the experimental studies reported in this review, dietary n-3 fatty acids from fish and fish oil had profound hypolipidemic effects in normal subjects and in hypertriglyceridemic patients with combined hyperlipidemia (type II-b) and types IV and V hyperlipidemia. In these carefully controlled metabolic experiments, dramatic reductions occurred in plasma triglycerides and to a lesser extent in plasma total cholesterol. Reductions in VLDL, chylomicrons, remnants, LDL, apo B, and apo E were also noted. HDL changes varied from subject to subject. These plasma lipoprotein changes occurred in subjects with non-insulin-dependent diabetes mellitus as well, without deterioration of diabetic control. Similar results are reported in two other papers in this volume. Fish oil did not cause deterioration of diabetic control. Whereas the mechanism of the hypolipidemic action of the n-6 rich vegetable oils containing linoleic acid such as corn or safflower oil still remains obscure, the mechanism of the hypolipidemic action of the n-3 fatty acids in fish oil is well documented. The synthesis of triglyceride and VLDL in the liver is greatly reduced by n-3 fatty acids. At the same time, the turnover of VLDL in plasma is shortened. In another study, LDL production was decreased. Combined with other dietary manipulations, such as a reduction in saturated fat and dietary cholesterol, the use of n-3 fatty acids to treat hyperlipidemia, especially hypertriglyceridemia, appears to have a well-supported rationale. Fish oil combined with a low cholesterol, low saturated fat diet has been shown to produce complementary effects. Total plasma cholesterol and LDL cholesterol were lowered by the low cholesterol, low saturated fat diet, whereas plasma triglyceride and VLDL were decreased by the fish oil. In most situations, the use of fish oil supplements should be regarded as pharmacologic therapy, particularly effective in severe hypertriglyceridemic states (e.g., chylomicronemia). However, a lifelong diet rich in fish may be protective against atherosclerosis as well. Further studies are required to delineate exact doses and precise indications for the use of fish oil in different types of hyperlipidemias and to differentiate the effects, if any, of the two major n-3 fatty acids in fish oil, EPA and DHA. The hypolipidemic effects of n-3 fatty acids coupled with their known antithrombotic actions (secondary to changes in prostaglandin secretion, platelet function, inhibition of growth factors, and enhancement of endothelial-derived relaxation factor) appear to have an important potential role in the control of coronary heart disease and other atherosclerotic disorders. Moreover, fish oil may prevent the "chylomicronemia" syndrome of type V hyperlipidemia.
在本综述所报道的实验研究中，来自鱼类和鱼油的膳食n-3脂肪酸对正常受试者以及患有混合型高脂血症（II-b型）、IV型和V型高脂血症的高甘油三酯血症患者具有显著的降血脂作用。在这些精心控制的代谢实验中，血浆甘油三酯大幅降低，血浆总胆固醇降低幅度较小。极低密度脂蛋白（VLDL）、乳糜微粒、残余颗粒、低密度脂蛋白（LDL）、载脂蛋白B（apo B）和载脂蛋白E（apo E）也有所降低。高密度脂蛋白（HDL）的变化因个体而异。这些血浆脂蛋白变化在非胰岛素依赖型糖尿病患者中也会出现，且不会导致糖尿病控制情况恶化。本卷中的另外两篇论文也报道了类似结果。鱼油不会导致糖尿病控制情况恶化。富含亚油酸的n-6植物油（如玉米油或红花油）的降血脂作用机制仍不清楚，但鱼油中n-3脂肪酸的降血脂作用机制已有充分记载。n-3脂肪酸可大幅降低肝脏中甘油三酯和VLDL的合成。同时，血浆中VLDL的周转缩短。在另一项研究中，LDL生成减少。与其他饮食调整措施（如减少饱和脂肪和膳食胆固醇的摄入）相结合，使用n-3脂肪酸治疗高脂血症，尤其是高甘油三酯血症，似乎有充分的理论依据。鱼油与低胆固醇、低饱和脂肪饮食相结合已显示出互补作用。低胆固醇、低饱和脂肪饮食可降低血浆总胆固醇和LDL胆固醇，而鱼油可降低血浆甘油三酯和VLDL。在大多数情况下，使用鱼油补充剂应被视为药物治疗，在严重高甘油三酯血症状态（如乳糜微粒血症）下特别有效。然而，终生富含鱼类的饮食也可能对动脉粥样硬化有预防作用。需要进一步研究来确定鱼油在不同类型高脂血症中的准确剂量和精确适应症，并区分鱼油中两种主要n-3脂肪酸二十碳五烯酸（EPA）和二十二碳六烯酸（DHA）的作用（如有）。n-3脂肪酸的降血脂作用及其已知的抗血栓形成作用（继发于前列腺素分泌、血小板功能的变化、生长因子的抑制以及内皮源性舒张因子的增强）似乎在冠心病和其他动脉粥样硬化疾病的控制中具有重要的潜在作用。此外，鱼油可能预防V型高脂血症的“乳糜微粒血症”综合征。
