Conjugated Linoleic Acid (CLA)

[Guest guest]

Dear Attilio, and All, I strongly recommend that you keep

your eyes on CLA's use as an anti-mammary cancer and anti-obesity agent. I

would also look for where this nutrient is sourced rather than just consider it

as a supplement. Adjusting the diet to include foods rich in this nutrient

would be the first consideration.

 

Respectfully,

Emmanuel Segmen

 

Dietary conjugated linoleic acid differentially alters fatty acid

composition and increases conjugated linoleic acid content in porcine adipose

tissue.

Br J Nutr 2003 Nov;90(5):915-28 (ISSN: 0007-1145)

Ostrowska E; Cross RF; Muralitharan M; Bauman DE; Dunshea FR

Department of Primary Industries, 600 Sneydes Rd, Werribee, VIC 3030,

Australia.

Conjugated linoleic acids (CLA) have been shown to decrease body fat

content in pigs. It is possible that feeding pigs diets rich in CLA may increase

carcass lipid CLA to levels that could provide health benefits when included as

a part of a healthy diet. Therefore, the aim of the present study was to

determine whether dietary CLA supplementation has any effect on the fatty acid

composition of subcutaneous and intramuscular adipose tissue in pigs.

Thirty-five female cross bred (Large White x Landrace) pigs (initial weight 57.2

kg and initial P2 back fat 11.5 mm) were used in the present study. Pigs were

housed individually and randomly allocated to one of six dietary treatments

(0.00, 1.25, 2.50, 5.00, 7.50 and 10.00 g CLA55 (55 g CLA isomers/100 g total

fatty acids; Natural Lipids Ltd, Hovdebygda, Norway)/kg) and fed their

respective diets for 8 weeks. Twelve CLA isomers in the diet and in pig tissue

lipids were separated by Ag+-HPLC. CLA was incorporated at fivefold higher

levels in subcutaneous fat as compared with intramuscular fat and in a

dose-dependant manner. Overall, the transfer efficiency of CLA was maximized at

5.00 g CLA55/kg. However, there was clear selectivity in the uptake or

incorporation of cis,trans-9,11 isomer over the trans,cis-10,12 isomer. In

general, CLA supplementation produced significant changes in skeletal muscle and

adipose tissue fatty acid composition, indicating that dietary CLA had a potent

affect on lipid transport and metabolism in vivo. Significant increases in

myristic, palmitic and palmitoleic acids and a reduction in arachidonic acid

were observed, suggesting an alteration in activity of delta5-, delta6- and

delta9-desaturases in pig adipose tissue. In conclusion, feeding pigs diets

supplemented with CLA increases carcass lipid CLA, but also results in changes

in the fatty acid profile in pig fat that could potentially outweigh the

benefits of CLA.

 

 

Effects of lipid-esterified conjugated linoleic acid isomers on platelet

function: evidence for stimulation of platelet phospholipase activity.

Biochim Biophys Acta 2003 Dec 30;1635(2-3):75-82 (ISSN: 0006-3002)

Al-Madaney MM; Kramer JK; Deng Z; Vanderhoek JY

Department of Biochemistry and Molecular Biology, The George Washington

University, Washington, DC 20037, USA.

The effects of four conjugated linoleic acid (CLA) isomers on in vitro

collagen-induced human platelet aggregation and thromboxane (TXB(2), the

inactive metabolite of the proaggregatory TXA(2)) production were examined. As

the free fatty acid (FFA), 9t, 11t-CLA was the most effective inhibitor of these

two processes (I(50)s of 2.2 and 4 microM, respectively) and the 9c, 11c-CLA was

the least effective (I(50)s of 8.3 and 37 microM) of the isomers tested. When

platelets were preesterified with either 25 microM 9t, 11t-CLA or 9c, 11c-CLA,

CLA incorporation in total platelet lipids increased from 0.24% to 0.31% and

0.38%, and most of this increase was found to be in the phosphatidyl choline and

phosphatidyl ethanolamine subclasses. The decrease in arachidonic acid (AA)

content in total fatty acids or phospholipids was an order of magnitude greater.

Furthermore, no significant differences between platelets prelabeled with either

9t, 11t- or 9c, 11c-CLA in the inhibition of collagen-induced aggregation and

TXB(2) formation were observed. However, platelets prelabeled with 9c, 11c-CLA

stimulated basal TXB(2) production (4-fold) which was not observed with

platelets pretreated with either 9t, 11t-CLA, linoleic acid or stearic acid.

This enhancement was associated with a 2.4-5-fold increase in the release of

endogenous AA. Our results suggest that the presence of a conjugated cis, cis

double bond appears to change the lipid environment sufficiently to stimulate

the basal platelet phospholipase activity, which in turn increases the formation

of TXB(2).

 

Physiologic melatonin concentration, omega-3 fatty acids, and

conjugated linoleic acid inhibit fatty acid transport in rodent hind limb

skeletal muscle in vivo.

Comp Med 2003 Apr;53(2):186-90 (ISSN: 1532-0820)

Dauchy RT; Blask DE; Sauer LA; Davidson LK; Krause JA; Smith LC;

Dauchy EM

Laboratory of Experimental Neuroendocrinolgy/Oncology, Bassett

Research Institute, Cooperstown, New York 13326-1394, USA.

Melatonin (MLT), the circadian neurohormone secreted by the pineal

gland in mammals during darkness, eicosapentanoic acid (EPA), and conjugated

linoleic acid (CLA) have established regulatory roles in cancer growth.

Investigations in our laboratory have indicated that these agents inhibit fatty

acid (FA) transport by tumors and several sub-types of white adipose tissue via

inhibitory G protein-coupled receptor mechanisms. Skeletal muscle constitutes

over 45% of human body mass and plays an important role in cancer cachexia and

obesity-related diseases. Since fatty acid oxidation is a major source of energy

for this tissue, we tested the hypothesis that physiologic MLT levels, EPA, or

CLA injected intravenously, inhibit FA uptake in rat skeletal muscle in vivo. We

used a surgical technique for catheterizing the femoral vein in rats that allows

rapid blood collection from the entire hind limb, while ensuring continuous

blood flow to the tissue. Blood acid/gas tensions and hematocrit were monitored

and remained constant during the course of each experiment. The MLT, EPA, and

CLA inhibited FA uptake by the tissue and lowered cAMP values. Glucose uptake

and glycerol production in the hind limb were not affected.These investigations

suggest a novel role for MLT, omega-3 FAs, and CLA in the regulation of FA

transport and fat metabolism in skeletal muscle.

 

Inhibition of stearoyl-CoA desaturase activity by the

cis-9,trans-11 isomer and the trans-10,cis-12 isomer of conjugated linoleic acid

in MDA-MB-231 and MCF-7 human breast cancer cells.

Biochem Biophys Res Commun 2002 Jun 21;294(4):785-90 (ISSN:

0006-291X)

Choi Y; Park Y; Storkson JM; Pariza MW; Ntambi JM

Department of Biochemistry, University of Wisconsin-Madison,

53706, USA.

Conjugated linoleic acid (CLA) is a collective term for a

group of positional and geometric conjugated dienoic isomers of linoleic acid.

CLA has been shown to have strong inhibitory effects on mammary carcinogenesis

both in vitro and in vivo. In this study, we investigated the regulation of

human stearoyl-CoA desaturase (SCD, EC 1.14.99.5) expression by CLA in human

breast cancer cell lines, MDA-MB-231 and MCF-7. Treatment of the cells with the

cis-9,trans-11 and trans-10,cis-12 CLA isomers (45 microM) did not repress SCD

mRNA in both MDA-MB-231 and MCF-7 cells. However, the cis-9,trans-11 and

trans-10,cis-12 CLA isomers significantly decreased SCD protein levels and SCD

activity in MDA-MB-231 cells. In MCF-7 cells, both isomers did not affect

protein levels, but they inhibited SCD activity. These results suggest that in

MDA-MB-231 cells the cis-9,trans-11 and trans-10,cis-12 CLA isomers regulate

human SCD by reducing SCD protein levels, while in MCF-7 cells both isomers have

a direct inhibitory effect on SCD enzyme activity. [© 2002 Elsevier Science

(USA).].

 

 

Conjugated linoleic acid isomers and mammary cancer

prevention.

Nutr Cancer 2002;43(1):52-8 (ISSN: 0163-5581)

Ip C; Dong Y; Ip MM; Banni S; Carta G; Angioni E; Murru E;

Spada S; Melis MP; Saebo A

Department of Experimental Pathology, Roswell Park Cancer

Institute, Buffalo, NY 14263, USA. Clement.Ip.

There is increasing evidence that individual isomers of

conjugated linoleic acid (CLA) may have unique biological or biochemical

effects. A primary objective of this study was to determine whether there might

be differences in the anticancer activity of 9,11-CLA and 10,12-CLA. This was

achieved by evaluating the reduction in premalignant lesions and carcinomas in

the mammary gland of rats that had been treated with a single dose of

methylnitrosourea and given 0.5% of either highly purified CLA isomer in the

diet. Our results showed that the anticancer efficacies of the two isomers were

very similar. At 6 wk after carcinogen administration, the total number of

premalignant lesions was reduced by 33-36%. At 24 wk, the total number of

mammary carcinomas was reduced by 35-40%. The concentration of each CLA isomer

and its respective metabolites was analyzed in the mammary fat pad. Tissue level

of 10,12-CLA was much lower than that of 9,11-CLA. The pool of metabolites from

each isomer was very similar between the two groups and represented only a small

fraction of total conjugated diene fatty acids. Feeding of 9,11-CLA resulted in

minimal changes in other unsaturated fatty acids. In contrast, feeding of

10,12-CLA produced a wider spectrum of perturbations. Small but significant

increases in 16:1 and 16:2 were detected; these were accompanied by decreases in

20:2, 20:3, 20:4, 22:4, and 22:6. The above observation suggests that 10,12-CLA

might be more potent than 9,11-CLA in interfering with elongation and

desaturation of linoleic and linolenic acids. In summary, our study showed that,

at the 0.5% dose level, the anticancer activity of 9,11-CLA and 10,12-CLA was

very similar, even though accumulation of 10,12-CLA in the mammary tissue was

considerably less than that of 9,11-CLA. These confounding changes of the other

unsaturated fatty acids in contributing to the effect of 10,12-CLA need to be

clarified.