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 Conjugated linoleic acid (CLA) is a mixture of 8
(and perhaps even more) different forms (or isomers)2 of
an 18-carbon fatty acid made by a high-heat industrial
process from linoleic acid (LA), the omega-6 (omega-6) essential
fatty acid (EFA). In nature, this is accomplished by bacteria
in the stomach of ungulates: beef, goats, sheep and other
cud-chewing animals (which include deer, moose, caribou,
elk, buffalo, yak, musk ox), and CLA is found in meat and
milk fat of these species.
Each of its eight different isomers has a different
spatial structure and each therefore has different action
in the body, with different effects on health. The isomer
found in dairy products is mainly the (delta)9c,11t-18:2
isomer.3 Butter normally contains about
5mg of CLA per gram of fat, but this can be increased
to 40mg per gram by feeding cows sunflower oil.4 Milk
chocolate contained 0.3mg of CLA per gram chocolate in
a study.5 Commercially, CLA is made by a high-temperature
(overheating) process, or by hydrogenation
of soybean6 or canola oils, or by transformation
carried out by bacteria in one of the four stomachs of
cud-chewing animals from the omega-6 EFA, LA. |
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 CLA
is made from LA, the omega-6 EFA, by flipping one
of the double bonds in the LA molecule
one carbon closer to the other one. This changes
the 'methylene-interrupted' double bonds present
in EFAs (double bonds start 3 carbons apart)
into 'conjugated' double bonds (double bonds
start 2 carbons apart). At the same time, one
of the double bonds found in the cis- configuration
in an EFA (hydrogen atoms on the carbons involved
in the double bond are on the same side of
the molecule) twists
180�. The hydrogen atoms are now in a more stable, but biologically less desirable trans- configuration
(hydrogen atoms on the carbons involved in the double bond are on opposite sides
of the molecule). Trans- means 'across'. Hence the name trans-
fatty acid.
Is CLA an Essential
Nutrient?
CLA is not an essential nutrient. It
is, like monounsaturated (n-9) and saturated
fatty acids, a non-essential fatty acid. It
is not required for human health. This means
that, unlike the omega-6 and omega-3 EFAs, which we
cannot live without, we can live on a CLA-free
diet a whole life time and continue to be healthy.
CLA
is also a trans- fatty acid. |
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 To
be fair, the 9c,11t-18:2 (the letter "t" after
the number "11" in this designation means: "trans")
isomer of CLA found in milk fat and beef appears to be one
of the more easily digested trans- fatty acids, and
is therefore less toxic than the types of trans- fatty
acids found in margarine, shortening, and partially hydrogenated
vegetable oils. However, CLA interferes with the conversion
of EFAs (especially omega-6) to derivatives from which the body
makes the eicosanoid (prostaglandin) hormones.8 This
should concern low fat dieters, who already get too little
omega-6 EFA, LA. It should also concern those who use flax oil
exclusively, because they get too much omega-3 in comparison
to their intake of omega-6, and CLA will make their low omega-6 status
even worse. |
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Conjugated double bond systems have antioxidant activity, and some
studies suggest that CLA can perform antioxidant functions. Other
studies suggest that CLA increases
oxidation, which is not so good. However, there are hundreds of molecules with
antioxidant activity equal to or better than that of CLA. Among those that, like
CLA, are oil-soluble there are vitamin A, carotene, vitamin E, and many complex
molecules with aromatic carbon rings. |
| Molecules with antioxidant
activity provide protection against degeneration, and hence
might have anti-cancer, anti-inflammatory, anti-diabetic,
and cardio-protective properties. However, hundreds of
molecules from nature provide equal or better protection
against degeneration. |
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| For instance,
about half of all edible green plants contain anti-cancer,
cardio-protective, anti-diabetic, anti-inflammatory ingredients-hundreds
of different ones-and they confer their protection in many
different ways. |
Some people in the marketplace suggest that CLA is protective
against degenerative conditions, but here too, the research is contradictory, and CLA may be over-rated.
In the following pages, I summarized 43 clinical studies done with CLA. The
remaining studies came to similar conclusions, or were of a technical nature.
I have tried to report fairly. Check out the studies, and judge for yourself.
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