β‐Oxidation of conjugated linoleic acid isomers and linoleic acid in rats

To assess the oxidative metabolism of conjugated linoleic acid (CLA) isomers, rats were force-fed 1.5-2.6 MBq of [1-14C]-linoleic acid (9c,12c-18:2), -rumenic acid (9c,11t-18:2), or-10trans,12cis-18:2 (10t,12c-18:2), and 14CO2 production was monitored for 24 h. The animals were then necropsied and the radioactivity determined in different tissues. Both CLA isomers were oxidized significantly more than linoleic acid. Moreover, less radioactivity was recovered in most tissues after CLA intake than after linoleic acid intake. The substantial oxidation of CLA isomers must be considered when assessing the putative health benefits of CLA supplements.