Review of the metabolic outcome of trans polyunsaturated fatty acids

Trans isomers of linoleic and alpha-linolenic acids are found in heated and used frying oils, and are subsequently ingested by human, in this review, we have shown to what extent the presence of a trans double bond can influe nce the biochemistry of the 18:2- and 18:3- fatty acids. Firstly, the oxida tion of the mono-trans 18:2 and 18:3 isomers accounts for the main metaboli c pathway, as these are oxidized in a similar or a greater extent than thei r corresponding cis homologues. However, the geometry of the double bonds i nfluences the esterification of the fatty acids as well as their conversion into long chain polyunsaturated isomers. in general, a trans double bond i s recognised as a saturated one by the acyltransferases. Nevertheless, a 9 cis double bond seems to be a prerequisite for the esterification of the 18 :3- fatty acids in human cholesteryl esters. 9 trans-18:2 and 9 trans- 18:3 isomers are from 2 to 5 times more converted into " trans dead end product s " (trans-20:2 and trans-20:3 isomers) than their corresponding cis isomer s. The trans 18:2- and 18:3 fatty acids are converted into trans isomers of arachidonic and eicosapentaenoic acids to a lesser extent than linoleic an d alpha-linolenic acids. However, the conversion of the 12 trans- 18:2 into 14 trans-20:4 is similar to that of linoleic acid into arachidonic acid.