Isomerization increases the postprandial oxidation of linoleic acid but not α-linolenic acid in men

Human lipid intake contains various amounts of trans fatty acids. Refined vegetable and frying oils, rich in linoleic acid and/or alpha -linolenic acid, are the main dietary sources of trans-18:2 and trans-18:3 fatty acids. The aim of the present study was to compare the oxidation of linoleic acid, alpha -linolenic acid, and their major trans isomers in human volunteers, For that purpose, TG, each containing two molecules of [1(-13)C]linoleic acid, alpha-[1(-13)C]linolenic acid, [1(-13)C]-9cis,12trans18:2, or [1(-13)C]-9cis,12cis,15trans-18:3, were synthesized. Eight healthy young men ingested labeled TG mixed with 30 g of olive oil. Total CO2 production and (CO2)-C-13 excretion were determined over 48 h, The pattern of oxidation was similar for the four fatty acids, with a peak at 8 h and a return to baseline at 24 h. Cumulative oxidation over 8 h of linoleic acid, 9cis,12trans-18:2, alpha -linolenic acid, and 9cis,12cis,15trans-18:3 were, respectively, 14.0 +/- 4.1%, 24.7 +/- 6,7%, 23.6 +/- 3.3%, and 23.4 +/- 3.7% of the oral load, showing that isomerization increases the postprandial oxidation of linoleic acid but not alpha -linolenic acid in men. - Bretillon, L., J. M. Chaldigny, J. L. Sebedio, J. P. Noel, C. M. Scrimgeour, C. E. Fernie, O. Loreau, P. Gachon, and B. Beaufrere. Isomerization increases the postprandial oxidation of linoleic acid but not cr-linolenic acid in men.