Introduction
Conjugated Linoleic Acid (CLA) is a naturally occurring free fatty acid found mainly in meat and dairy products, in small amounts. CLA was discovered by accident in 1978 by Michael W. Pariza at the University of Wisconsin while looking for mutagen formations in meat during cooking. As implied by the name, the double bonds of CLAs are conjugated.
Biochemistry
Most studies of CLA have used a mixture of isomers wherein the c9, t11-CLA and t10, c12-CLA isomers were the most abundant.
Conjugated linoleic acid is a trans fat, though some researchers claim that it is not harmful in the same fashion as other trans fatty acids, but rather is beneficial. CLA is a conjugated system, and in the United States, trans linkages in a conjugated system are not counted as trans fat for the purposes of nutritional regulations and labeling. CLA, as well as some trans isomers of oleic acid, is produced by microorganisms in the rumen of ruminants. Non-ruminants, such as humans, are able to produce some isomers of CLA from some trans isomers of oleic acids, such as vaccenic acid, which is converted to CLA by delta-9-desaturase.
Diet and health
Various antioxidant and anti-tumor properties have been attributed to CLA, and studies on mice and rats show promising results in reducing mammary, skin, and colon tumor growth.
A European team led by the Swiss scientist Lukas Rist has found that mothers consuming mostly organic milk and meat products have about 50 percent higher levels of rumenic acid in their breast milk. Studies on CLA in humans show a tendency for reduced body fat particularly abdominal fat, changes in serum total lipids and decreased whole-body glucose uptake. The maximum reduction in body fat mass was achieved with a 3.4 g daily dose.
CLA supplementation has, however, been shown to increase C-reactive protein levels, possibly induce oxidative stress, reduce insulin sensitivity and increase lipid peroxidation. However, the significance of these findings is unknown, and other studies suggest that CLA may protect cells from oxidative damage by increasing glutathione levels without inducing lipid peroxidation. It remains possible, however, that observations of increased markers of lipid oxidation may be related to potentially desirable lipolytic effects. Further studies are necessary to establish clinical significance.
Dietary Sources
Kangaroo meat may have the highest concentration of CLA when compared with other foods. Food products of grass-fed ruminants (e.g. lamb, beef) are good sources, and contain much more CLA than those from grain-fed animals. In fact, products of grass-fed animals can produce 300-500% more CLA than cows fed the typical diet of 50% hay and silage, with 50% grain.
Eggs are also rich in CLA, and it has been shown that the CLA in eggs survives the high temperatures encountered during frying.
Possible side effects of CLA in humans
There are concerns that the use of CLA by overweight people may increase insulin resistance, possibly increasing the risk of developing diabetes. However, this evidence is controversial, and other studies report no changes in insulin sensitivity.
A recent study (2006) by the US Department of Agriculture suggests that CLA can induce essential fatty acid redistribution in mice. Specifically, changes in docosahexaenoic acid (DHA) and arachidonic acid (AA) were observed in various organ tissues. A study of CLA supplementation in hatching chicks (2005) showed high mortality and low hatchability rates among CLA-supplemented groups, and also a decrease in brain DHA levels of CLA-treated chicks. These studies raise the concern that CLA may pose a risk vis-Ã -vis cardiovascular or inflammatory disease. However, whether these changes also occur in humans, and whether they may be clinically relevant, has yet to be established.
What does it do and what scientific studies give evidence to support this?
Through advanced lipid technology, a CLA synthesizing process allows for precision intake through premeasured soft gel capsules. This allows for precise CLA intake at determined time intervals without the high-calorie food consumption. Not only has CLA been shown to increase muscle mass while reducing body fat, studies have also shown remarkable anti-catabolic, antioxidant, and immune enhancement benefits.
Although all the intricacies of CLA are not fully understood, it is widely accepted in the research community that CLA counterbalances the negative effects of linoleic acid and regulates fat and protein metabolism in animals. CLA increases feed efficiency and also points to a potent nutrient repartitioning effect. This significant change in body composition can also be attributed in part to CLA’s effect on immune function. CLA has been shown to inhibit the lean tissue wasting caused by high levels of these cytokines.
Actual human studies are on the way with anticipation of similar outcomes. CLA may be the most significant bodybuilding nutrient discovered in this decade. With anti-catabolic effects rivaling even the strongest pharmaceutical compounds, CLA is a naturally occurring nutrient with the ability to help you pack on lean muscle, reduce body fat and at the same time possess health-promoting properties.
Diabetes and large doses
Larger doses of the 50:50 CLA formulation hold out tantalizing prospects for helping people with type II diabetes, according to another trial reported at the ACS meeting. Martha Belury of Northwest Hospital in Seattle and her colleagues at Purdue University in West Lafayette, Ind., tested nine people who have this adult-onset form of diabetes. The researchers gave them daily capsules containing either 6 g of safflower oil or CLA daily for 8 weeks. As in the other human trials reported at the meeting, neither the volunteers nor the researchers knew who got CLA until the study ended.
Fasting blood sugar, or glucose, was moderately improved in people getting the CLA supplements but not in those getting the safflower oil. Similarly, only the CLA group experienced a significant lowering in blood concentration of triglycerides, which are groups of fats known to increase the risk of heart disease. Beneficial triglyceride-lowering was seen in a study with diabetic rats.
Most exciting and definitely the most significant, was the finding that people taking the CLA supplement had lower blood concentrations of the hormone leptin compared with the volunteers taking safflower oil. Other researchers have associated elevations in blood leptin concentrations with obesity. Most diabetes drugs today are so potent that they literally have toxic side effects. If CLA offers pharmaceutical benefits without the toxicity, it may provide some individuals with an alternative to this drugs-or at least a way to ratchet down their drug doses.
We think CLA binds to a [cellular] receptor that is similar to one that some anti-diabetes drugs target.
It decreases tumor formation, and is toxic to existing tumors, is preventative and therapeutic, and is not destroyed by cooking. CLA affects Type II diabetes, fat synthesis, lupus, atherosclerosis and immune system function. It’s a remarkable molecule.