PART 6: Dose and Effectiveness

Taken together, what do these studies say about the health value and future of
CLA? It seems that CLA is highly over-rated in terms of its human health benefits.
More sizzle than steak, as the saying goes. There are several kinds of possibly
serious negative side effects from the use of CLA that should not be ignored.
These negative effects are found mainly in animals, and accompany the use of
doses substantially higher than those used in humans.
At the doses used in humans, the research results are quite disappointing. Most
human studies find no benefits in the degenerative conditions for which CLA is
recommended: weight loss, immune function, cardiovascular problems, and antioxidant
functions. The usual doses of CLA used in animals greatly exceed those used in
human studies. This may explain why animal studies come up with better results
than human studies, and my also explain the negative effects of CLA on liver
and insulin in rats, and the changes in yolk quality and hatchability in eggs.
So there appears to be a dose-related shadow side to CLA. Remove the shadow by
lowering the dose, and the benefits also disappear.

If the Results are Mediocre, what Drives CLA
promotion? What drives CLA promation is obviously
profit. Cheap sunflower oil can be sold at retail for
about $150 per pound. In comparison, a pound of Udo's Choice
Oil Blend, which contains about 75% undamaged EFAs
(50% omega-3), retails for about $20.
Natural Sources of CLA: Cream, nature's richest
natural source of CLA, contains 5mg/gram (0.5%) of fat. The dairy
isomer
of CLA is mostly c9,t11-18:2. That much is apparently safe and desirable
for calves. That much CLA in butter is probably safe for humans as
well. At 0.5% CLA, a tablespoon (14 grams) of butter provides about
70mg of CLA. To get 3 grams of CLA from butter, one would need to
eat more than 40 tablespoons of it, which is 560 grams of 1.25 pounds
of butter. That's a lot more than can be recommended, even if EFA
intake is optimal (about 1 tablespoon/body weight in winter; less
in summer), the level that makes skin soft and velvety (more in winter,
less in summer). By the way, 560 grams of butter is 560 x 0.8 (butter
is 20% water) x 9 (calories per gram) = 4,032 calories.
Butter, nature's richest source of CLA, does not provide
any creature with very much of it. This may explain why high levels
result in disturbing negative (side)
effects. In commercial preparations, the c9, t11- isomer is found mixed with
large amounts of the t10, c12-18:2 (the letter "t" before
the number "10" means: "trans") isomer,
along with smaller amounts of the
other six CLA isomers. Each of these has different properties and will therefore
have different effects on cell and tissue biochemistry. The specific effects
of all isomers are not yet known, but need to be known before safe recommendations
for this new mixture of CLA isomers is recommended for health.
Commercial preparations also differ from one another in the relative
amounts of the different isomers they contain. According
to tests that have been carried
out, they even differ from batch to batch. Therefore research done on one
commercial CLA preparation cannot be automatically transferred
to another.
This
point, conveniently overlooked by manufacturers, is unknown
to most consumers. To effectively treat human diseases, for
which CLA showed benefits in animals, larger doses would
be needed. Instead of 3 grams/day, on which we based out
calculations above, and which is already very high when compared
to what butter (the richest natural source) could supply,
CLA doses would need to be even higher.
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