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 influence the biochemistry of the 18:2- and 18:3- fatty acids. Firstly, the oxidation of the mono-trans 18:2 and 18:3 isomers accounts for the main metabolic pathway, as these are oxidized in a similar or a greater extent than their corresponding cis homologues. However, the geometry of the double bonds influences the esterification of the fatty acids as well as their conversion into long chain polyunsaturated isomers. in general, a trans double bond is 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 products " (trans-20:2 and trans-20:3 isomers) than their corresponding cis isomers. 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 and 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.