Conjugated Linoleic Acid – ‘A unique fatty acid in beef and dairy products with immune benefits’
Authors: C Field, Department of Medicine, University of Alberta
From a presentation at a seminar for health professionals, October 2000
There is considerable interest in the potential health benefits of conjugated linoleic acid (CLA). In animal studies feeding CLA has been shown to prevent the growth of tumor cells, prevent lipid accumulation in arteries and alter metabolism (decrease body fat and increase lean muscle).
Conjugated linoleic acid (CLA) is a group of fatty acids that are positional and geometric isomers of the dietary essential fatty acid linoleic acid. CLA is produced by rumen microorganisms and is found in small amounts in the fat from beef and dairy cows, sheep and goats. For the past 4 years, our laboratory has been studying this novel animal fat. We have developed analytical methods to identify the content of CLA in tissues or foods. We have compiled data on the content of CLA in Canadian beef and dairy foods. Using a series of 7-day food records we have estimated the CLA consumption in the Canadian population.
Our recent work has examined the biological effects of CLA in an animal model. We have found that CLA enhanced cell-mediated immune function, but only when CLA was fed in a saturated fat diet containing a polyunsaturated to saturated fatty acid ratio of 0.2. CLA supplementation did not change immune function when it was added to a diet containing a P/S ratio of 1.0 (the level recommended for the general population). CLA was also more readily incorporated into fat stores and immune cell membranes when fed in a low P/S diet.
We have also examined the effects of CLA on human breast tumor cells and found that adding CLA reduced tumor cell growth but did not alter the ability of tumor cells to adhere to the extracellular matrix, an important component in facilitating the spread of a tumor in the body. However, CLA was highly rapidly incorporated into tumor cell membranes, which may be the mechanism for its anti-tumor effects.
CLA is a unique fat, knowledge of the content of this fat in our foods, our usual intake and its unique biological properties will aid nutritionists in assessing the importance of particular animal foods in the Canadian diet.
For more information on CLA, visit -
The Food Research Institute of the University of Wisconsin