Conjugated Linoleic Acid
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Conjugated Linoleic Acid, also known as CLA, is not one substance but rather a group of compounds similar to linoleic acid but are structurally slightly different as they contain conjugated bonds. Conjugated bonds are found in unsaturated compounds where two double bonds are separated by a single bond. Conjugated linoleic acid is both a trans fatty acid and a cis fatty acid. The cis bond causes a lower melting point and ostensibly also the observed beneficial health effects. Unlike other trans fatty acids, conjugated linoleic acid may have beneficial effects on human health.
Most of the commercial preparations of CLA contain two isomers of linoleic acid predominately, cis-9, trans-11 CLA and trans-10, cis-12 CLA with a smaller amount of other isomers. Each isomer exerts a slightly different biological effect. The health benefiting actions of CLA are vast and include anticarcinogenic, antiatherogenic, and antidiabetic action and also changes body composition .
CLA can be found in animal tissue as well as a variety of food sources mainly from ruminating animals such as cows, goats, and sheep. Vegetable oils are poorer sources of CLA, however it can be produced from linoleic acid found in safflower oil, sunflower oil, corn oil and canola oil. Nuts and seeds also contain CLA.
The following are the primary uses for Conjugated Linoleic Acid: 
- Cancer Prevention: CLA has been shown to inhibit the proliferation of malignant breast, colorectal, prostate, melanoma, and lung cancers in animal and in vitro studies. The mechanism by which CLA is able to do this is not completely understood. It is thought that it both inhibits carcinogens and also protects tissues. It also modulates carcinogenesis.
- Cardiovascular Disease (CVD) Prevention: Animal studies have shown that CLA has a hypolipidemic effect. Atherosclerotic plaques have been shown to regress in CLA-supplemented animals and free fatty acids and triglycerides have been lowered.
- Type II Diabetes: CLA has recently been shown to normalize impaired glucose tolerance and improve hyperinsulinemia in animal studies and may be an important therapeutic option in the prevention and treatment of non-insulin dependent diabetes.
- Changing Body Composition: CLA has been shown to reduce body fat and increase lean body mass in animal models. This benefit appear to work independently of food intake. It appears that the trans-10, cis-12 CLA is responsible for this effect.
- The amounts of the two most studied isomers of CLA, cis-9, trans-11 and trans-10, cis-12 CLA vary in the products. There are also different amounts of other isomers of CLA in the various preparations.
- Adult: typical dose is 1-2g/day
Conjugated Linoleic Acid is generally regarded as safe. Some safety precautions include:
- Side-effects are rare, but may include: gastrointestinal complaints such as nausea with doses up to 2g/day.
- Children: Lack of long term studies on safety suggests that CLA supplementation should be avoided in this population.
- Pregnancy and Breastfeeding
- Lack of long term studies on safety suggests that CLA supplementation should be avoided in this population.
- individuals with hypersensitivity to any component of CLA.
- Hendler Sheldon S, Rorvik David (Editors) (2001) PDR for Nutritional Supplements, Medical Economics Company Inc.