NutraIngredients-USA yesterday ran an article comparing a study using CLA-fed mice and another using CLA-fed rats.
Led by Dr. Martha Belury, the study involving mice was said, in the Ohio communiqué, to have results that raised questions about how the fatty acid behaves in humans.
Cognis is looking to qualify the methods and objectives of the studies so as to protect the reputation of its branded fat loss Tonalin CLA, which it claims holds well over half of the ingredient category's market share.
Moreover, Cognis has refuted that it funded the studies, though it says it has given grants to Ohio State University in the past.
"The study conclusions confirmed what we have known for years about CLA," said Christine Peggau, senior marketing manager, Cognis Nutrition & Health. "CLA safely and effectively reduces fat and maintains lean muscle mass."
The mouse study appears in a recent issue of the Journal of Lipid Research, while the rat study will appear in an upcoming issue of the Journal of Nutritional Biochemistry.
In the first study, the mice that were fed a CLA-supplemented diet lost weight quickly, but also accumulated excessive amounts of fat in their livers. However, Cognis said this fat increase was intentionally triggered using CLA as means to induce diabetes in the mice and in turn study the effect of an anti-diabetes drug.
"…It was not a surprise that the mice developed fatty livers," said Peggau. "In fact this was part of the study design."
Excessive fat accumulation in the liver is linked to insulin resistance and is a characteristic of Type 2 diabetes.
"What is overlooked in the news release is the significance of the anti-diabetes drug," said Peggau. "Dr. Belury intentionally injected CLA into the mice because she wanted to study the mechanisms that create insulin resistance as well as to study the effectiveness of the drug."
"Studies have shown that mice-because they are so lean-develop fatty livers or diabetes when injected with CLA. This does not hold true for other animals higher in fat such as pigs, rabbits, rats, hamsters or, of course, humans."
In the second study, CLA didn't help rats lose weight they had gained prior to taking the supplement. However, it decreased the amount of fat accumulated in the rats' livers due to this weight gain. As a result, the rats were less resistant to insulin.
"Unlike the mice, the rats reacted differently to the CLA-as expected," said Peggau. "The rats, fatter rodents than mice, did not develop fatty livers."
The results of the rat study were reported by Ohio State University as being more favorable in terms of the light they shed on the effect CLA has on insulin resistance.
"The study in rats demonstrated that CLA actually reduced hepatic steatosis and reduced fasting glucose in Wistar rats," said Dr. Belury. "This is potentially a good thing for managing insulin resistance and type 2 diabetes."
The Wistar rats used in the study are most resistant to the overall fat lowering effect of CLA, said David Cai, senior scientist at Cognis, but were specifically chosen because of this to examine the pathway in which CLA works and which it does not.
A Cognis-funded study on CLA and humans was published last year in the International Journal of Obesity and yielded encouraging results for the weight-loss ingredient.
The human six-month randomised, double-blind, placebo-controlled study reported CLA safely reduced the body fat mass of 40 overweight and obese subjects by 2.2 lbs and their body weight by 1.3 lbs. The placebo group gained 1.5 lbs of body fat mass and 2.4 lbs of body weight.
In this study, no impact of CLA was found on insulin resistance, blood lipid levels or resting metabolic rate.