Apparent lymphatic recovery of conjugated linoleic acid (CLA) in rats was considerably lower than for linoleic acid, approximately 55% versus 80% for 24 hr, although the distribution in lymph lipoproteins was similar. Not all the CLA constituents were recovered equally, and more tt-isomers were recovered than ct- or tc-isomers in relation to the composition of CLA given. When rats were fed CLA or linoleic acid at the dietary level of 1% for 2 weeks, there were detectable differences in the incorporation of CLA in various tissues, and adipose tissue and lung contained the highest proportion, whereas a limited amount was incorporated into the brain. In general, 9c, 11t/9t,11c isomers were the predominant CLA followed by tt-isomers. Also, CLA was differently incorporated into individual phospholipids in the liver. No effects were observed on serum and liver lipid levels, but the concentration of prostaglandin E2 (PGE2) in serum and spleen tended to be reduced by CLA, the difference in the former was statistically significant. CLA did not increase tissue TBA values. Thus, the metabolic effect of CLA may not be attributed to a single entity.
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