Ackman R G
Canadian Institute of Fisheries Technology, Technical University of Nova Scotia, Halifax, Canada.
Lipids. 1992 Nov;27(11):858-62. doi: 10.1007/BF02535864.
Both preventive and curative therapies have created a considerable demand for eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The most common sources for omega 3 fatty acids are fish oil. The concentrations of EPA and DHA in commercial oils, after modest enrichment, reach about 300 mg/g; alternative technologies can produce reasonably priced fish oils containing 400 or even 500 mg/g of omega 3 acids. When the acids are liberated from the glycerides, concentrates of ethyl esters or free acids with 65 to 70% total omega 3 fatty acids (at least 50% EPA + DHA) are readily prepared. Difficulties have arisen because most clinical trials have used fish oils of unspecified composition, and some trials are now based on either ethyl esters or free acids. There are at least three different, but not mutually exclusive, absorption routes in humans, namely the preduodenal route, the lymphatic route via chylomicrons, and the route via the portal vein to the liver. This makes it difficult to compare results. The difficulty in obtaining dose-related clinical data may in part be due to the form in which the omega 3 acids are offered and due in part to the natural presence of these fatty acids in the body. The nontriglyceride forms, especially the free acids, have been advocated for standardization of trials to facilitate interlaboratory comparisons.
预防性和治疗性疗法都对二十碳五烯酸（EPA）和二十二碳六烯酸（DHA）产生了相当大的需求。ω-3脂肪酸最常见的来源是鱼油。市售鱼油经过适度富集后，EPA和DHA的浓度可达约300毫克/克；其他技术可以生产出价格合理、ω-3酸含量为400甚至500毫克/克的鱼油。当这些酸从甘油酯中释放出来时，很容易制备出总ω-3脂肪酸含量为65%至70%（至少50%为EPA+DHA）的乙酯或游离酸浓缩物。困难在于，大多数临床试验使用的是成分未明确的鱼油，而且现在一些试验基于乙酯或游离酸。人体中至少有三种不同但并非相互排斥的吸收途径，即十二指肠前途径、通过乳糜微粒的淋巴途径以及通过门静脉到肝脏的途径。这使得比较结果变得困难。难以获得与剂量相关的临床数据，部分原因可能在于ω-3酸的给药形式，部分原因在于这些脂肪酸在体内的自然存在。非甘油三酯形式，尤其是游离酸，已被提倡用于试验标准化，以促进实验室间的比较。
