Effets et métabolismes spécifiques des acides gras ω3 : Acides gras oméga 3 : aspects métaboliques

Abstract

Omega 3 fatty acids are issued from linolenic acid (18:3ω3). Nutritional interest about ω3 fatty acids has begun since the epidemiological studies of Dyerberg et al. have shown a relationship between consumption of marine fats and reduction of cardiovascular diseases. Long-chain ω3 fatty acids, mainly eicosapentaenoic (20:5ω3 or EPA) and docosahexaenoic (22:6ω3 or DHA) acids, are considered to be the main bioactive components in marine sources. Other studies have confirmed that consumption of fish ou EPA/DHA supplements may reduce mortality in patients who have suffered from myocardial infarction. Beneficial effects of ω3 fatty acids are also recognized in inflammatory disorders. The main mechanism involved for those effects is assumed to be the interference between long-chain ω3 fatty acids and the arachidonic acid (AA) metabolism in blood and vascular cells. In those cells, AA may be released from membrane phospholipids by phospholipase A 2 and subsequently oxygenated into eicosanoids (overall called AA cascade). According to the cell, oxygenated products from AA include thromboxane (platelets), prostacyclin (endothelial cells) and leukotrienes (leukocytes). EPA and DHA can interfere with AA cascade by several ways to reduce the vascular risk. However, high intake of such fatty acids may increase lipid peroxidation and have deleterious effects, in particular in subjects suffering from oxidative stress, whereas law may exert antioxidant activity. We conclude that a moderate consumption of long-chain ω3 fatty acids can protect against cardiovascular dysfunction.