12.6 What is Conjugated Linoleic Acid?
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This article is from the Chemistry FAQ, by Bruce Hamilton B.Hamilton@irl.cri.nz with numerous contributions by others.
12.6 What is Conjugated Linoleic Acid?
Conjugated linoleic acid describes the group of positional and geometric
isomers of linoleic acid ( cis-9,12-octadecadienoic acid ) that have a
conjugated double bond system starting at carbon 9, 10, or 11. They can be
either cis or trans, or various combinations of them. The more abundant
isomers in food are believed to be the cis-9, trans-11, and the trans-10,
cis-12 isomers. It's very difficult to separate the cis-9, trans-11 and
trans-9, cis-11 isomers, however the cis-9, trans-11 form is usually
considered the important and usually dominant isomer.
They are typically produced by bacteria in the rumen of ruminants because
the hydrolysis of fats in the rumen produces more unesterified linoleic
acid than is available to bacteria in other digestive systems. Plants
also contain conjugated linoleic acid, but there is much less of the
cis-9, trans-11 isomer, which is believed to be the biologically active
isomer. Foods that contain CLA are lamb, beef, turkey and dairy fat products,
ranging from 2.5 - 11 mg/g of fat - of which 75% or more is the cis-9,
trans-11 ( or trans-9, cis-11 ) isomer. CLA is of interest because it has
displayed antimutagenic activity in animals and human cell tests [6,7].
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