possible need for caution with Conjugated linoleic acid supplements(info on dairytoo)

[Lani]

Carcinogenesis. 2007 Jan 27; [Epub ahead of print]
The t10,c12 isomer of conjugated linoleic acid stimulates mammary tumorigenesis in transgenic mice overexpressing erbB2 in the mammary epithelium.

Ip MM,
McGee SO,
Masso-Welch PA,
Ip C,
Meng X,
Ou L,
Shoemaker S.
Department of Pharmacology & Therapeutics, University at Buffalo, Buffalo, NY.
Conjugated linoleic acid (CLA), a family of isomers of octadecadienoic acid, inhibits rat mammary carcinogenesis, angiogenesis, and lung metastasis from a transplantable mammary tumor. c9,t11-CLA, the predominant isomer in dairy products, and t10,c12-CLA, a component of CLA supplements, are equally effective. The objective of the current studies was to test the efficacy of these two CLA isomers in a clinically relevant breast cancer model. Transgenic mice overexpressing erbB2 in the mammary epithelium were fed control or 0.5% CLA-supplemented diets continuously from weaning. Unexpectedly, t10,c12-CLA stimulated lobular hyperplasia of the mammary epithelium and accelerated mammary tumor development, decreasing median tumor latency to 168 days of age compared to 256 and 270 days in the c9,t11-CLA and control groups, respectively. Metastasis was also increased by t10,c12-CLA, with percent of tumor-bearing mice with lung metastasis 73%, 14%, and 31%, in the t10,c12-CLA, c9,t11-CLA and control groups, respectively. A second study, in which CLA administration was initiated after puberty, confirmed the stimulatory effect of t10,c12-CLA on mammary tumor development and metastasis. Additionally, t10,c12-CLA, but not c9,t11-CLA, increased the size of the liver, heart, spleen and mammary lymph node. The effects of t10,c12-CLA were not specific to erbB2 transgenic mice, as t10,c12-CLA supplementation increased proliferation in the mammary epithelium of both wild type FVB and FVB/erbB2 mice. Moreover, the number of terminal end buds, the mammary epithelial structures most sensitive to a carcinogenic insult, was increased 30-fold in FVB/wild type mice fed t10,c12-CLA. These data suggest that it would be prudent to avoid CLA supplements containing the t10,c12-CLA isomer. However, even though c9,t11-CLA was not efficacious in the erbB2 model, its ability to inhibit mammary tumor development in rat models suggests that it may have activity for prevention of some types of breast cancer.
PMID: 17259656 [PubMed - as supplied by publisher]

[heblaj01]

Thanks Lani for this post on CLA which carries the warning about dairy products.
I hope that very low fat dairy foods such as skim milk, 0.1% fat cottage cheeses & yogurts can still be safely consumed if the two forms of CLA are concentrated in the fat as is stated in this article written before the new info became available:
http://www.sciencenews.org/articles/20051029/food.asp
Inflammation-Fighting Fat

The article makes note of the fact that grass fed cows are producing more of the "good" CLA (c9,t11-CLA) than grain fed ones which tend to produce more of the "bad" CLA (t10,c12-CLA). Nevertheless, since the new research paper states that regular milk carries mostly c9,t11-CLA (elsewhere the "bad" one is said to be traces ), then low fat dairy products must be very low in t10,c12-CLA whatever the diet of the cows.
Consuming these low fat products would still safely provide protein/calcium but none of the benefits of c9,t11-CLA. This assumes that they are free from pollutants such as insecticides, estrogens, antibiotics etc... an other worry to take care of.

[R.B.]

Thank you very much for these posts - a whole another subject.

The trial is fascinating as is the whole subject.

CLA is "just" another form of linoleic acid, with the double bonds in different slots in the chain and different angles yet the effects are so different.

This is all the result of the chains simply being another shape. Mind boggoling complexity.

http://jchemed.chem.wisc.edu/journal...c/absA302.html

It really emphaises the potential importance and subtly of the bodies utilisation of fats. It emphasis the potential power of trans fats.

Grass feed livestock has higher omega threes too.

I have only grazed this link I found more or less by accident. It is very thought provoking.

http://209.85.135.104/search?q=cache...ient=firefox-a

Again thank you for that.

Serious food for thought when I have time.

[heblaj01]

Once commercially available, pure cis-9-trans-11 CLA could provide a way to avoid the unwanted concurrent absorption of the other isomer trans-10-cis-12 CLA as is the case when consuming dairy or currently available CLA supplement pills.
http://www.ucd.ie/cscb/main_pages/news/news090307.htm
March 9, 2007
CSCB and TCD researchers team up with Teagasc to study food supplement that could prevent the development of diabetes and atherosclerosis