Acides gras polyinsaturés trans : Aspects métaboliques

Abstract

Trans isomers of linoleic and linolenic acids are usually found after heat treatment of vegetable oils (refined and used frying oils). These trans fatty acids can be like their corresponding cis isomers be oxidized and therefore used for energy production. Some of them can also be converted into long chain fatty acids which are trans isomers of arachidonic, eicosapentaenoic and docosahexaenoic acids. However, their conversion is influenced by the position of the trans ethylenic bond. In general, a trans double bond is recognised as a saturated one by the acyltransferase, and a 9 cis double bond seem to be of importance for the esterification of the 18:3 isomers in human cholesteryl esters. 18:2 and 18:3 isomers having a trans ethylenic bond in the Δ 9 position are preferentially converted into trans dead end products (trans-20:2 and 20:3 isomers).