Can adults adequately convert alpha-linolenic acid (18:3n-3) to eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3)?

作者：HELGA GERSTER · 发表于：PubMed · 年份：1998 · 被引用次数：409 · 研究领域：Fatty Acid Research and Health、Eicosanoids and Hypertension Pharmacology、Peroxisome Proliferator-Activated Receptors

A diet including 2-3 portions of fatty fish per week, which corresponds to the intake of 1.25 g EPA (20:5n-3) + DHA (22:6n-3) per day, has been officially recommended on the basis of epidemiological findings showing a beneficial role of these n-3 long-chain PUFA in the prevention of cardiovascular and inflammatory diseases. The parent fatty acid ALA (18:3n-3), found in vegetable oils such as flaxseed or rapeseed oil, is used by the human organism partly as a source of energy, partly as a precursor of the metabolites, but the degree of conversion appears to be unreliable and restricted. More specifically, most studies in humans have shown that whereas a certain, though restricted, conversion of high doses of ALA to EPA occurs, conversion to DHA is severely restricted. The use of ALA labelled with radioisotopes suggested that with a background diet high in saturated fat conversion to long-chain metabolites is approximately 6% for EPA and 3.8% for DHA. With a diet rich in n-6 PUFA, conversion is reduced by 40 to 50%. It is thus reasonable to observe an n-6/n-3 PUFA ratio not exceeding 4-6. Restricted conversion to DHA may be critical since evidence has been increasing that this long-chain metabolite has an autonomous function, e.g. in the brain, retina and spermatozoa where it is the most prominent fatty acid. In neonates deficiency is associated with visual impairment, abnormalities in the electroretinogram and delayed cognitive development. In adults the potential role of DHA ...