TRANS ISOMERS OF LONG-CHAIN N-3 POLYUNSATURATED FATTY-ACIDS IN TISSUELIPID CLASSES OF RATS FED WITH HEATED LINSEED OIL

The isomerization of linolenic acid into mono- and di-trans isomers ta kes place dur ing heat treatment. One of these compounds, 18:3 Delta 9 c,12c,15t can be desaturated and elongated to form, in particular, the trans isomers of eicosapentaenoic and docosahexaenoic acids. This stu dy was undertaken to observe the incorporation of these trans long-cha in n-3 polyunsaturated fatty acids into the lipid classes of several t issues. Rats were fed for 8 weeks with heated linseed oil containing h igh levels of trans linolenic acid isomers. The lipid classes of the l iver, kidney, heart and adrenals of these rats contained various level s of these compounds. The 20:5 Delta 5c,8c,11c,14c,17t represented bet ween 80 and 90 % of the total 20:5 in the phospholipids, but 22:5 Delt a 7c,10c,13c,16c, 19t and mainly 22:6 Delta 4c,7c,10c,13c, 16c,19t wer e only present in small quantities. This may indicate that the cis fat ty acids are better metabolized in these cases. Among the tissues stud ied, it was interesting to note a high level of 22:5 Delta 19t in the adrenals, particularly in cholesterol esters. (C) Inra/Elsevier, Paris .