CLA (conjugated linolenic acid) is a natural fatty acid present in beef and other ruminant meats, and dairy products. CLA is metabolized by bacteria in the stomachs of cows based on the grass they eat, but modern feeding methods of gains and prepared feed products have reduced the natural CLA content of many meats. In addition, due to recent reductions of meat and dairy consumption in Western diets, the average intake of CLA has fallen substantially. When the fat is removed from a dairy product to allow a low-fat claim, CLA is lost as well.
This has lead to an increased market for CLA in dietary supplements and as a food additive. Its popularity is based on the dual actions of CLA; a reduction of total body fat mass and an increase in the lean body mass.
The reasons for this result are well documented: dietary fat consumption that is not burned for energy as triglycerides are taken up by fat cells – a system in which the enzyme lipoprotein lipase is responsible.
CLA inhibits this enzyme, and diverts the triglycerides into muscle cells to be burned as energy. Within the cell, CLA promotes the activity of another enzyme, carnitine palmitoyl transferase, which is responsible for the oxidation and the burning of fat.
In a randomized, double-blind, placebo-controlled study conducted at an independent research institute, there were 180 obese or overweight adults with a body mass index between 28 and 32 (25-30 is considered “overweight,” and over 30 is “obese”)..
For six months the participants received either 3.4g of CLA or a placebo (olive oil) daily.
Initial results were evident eight to 12 weeks into the study, but at the end of the six months the reduction of fat mass was seen to be around 4-5 pounds greater than the placebo –about the same as 8-10 sticks of butter.
Lean body mass increased by an average of 0.9 pounds (14 ounces) more in the CLA group than in the placebo group. Particularly interesting was the location of the reduced fat mass –primarily focused in the abdomen and legs. This provides support for CLA’s reputation as a body shaper.
The CLA was well-tolerated by all the participants over the six-month period, enhancing its reputation for safety over time. The researchers also tested for indication of inflammatory or insulin sensitivity changes among a sub group of 41 participants. This is an important consideration since overweight and obese people have a higher risk of developing metabolic syndrome or type-II diabetes. No negative effects on insulin sensitivity were found, and there was a slight indication of improved sensitivity.