Understanding the mechanisms and implications of how CLA reduces fat is key to harvesting benefits for humans, says Dr. Martha Belury.
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Dr. Martha Belury
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How does CLA fight fat and what are the implications?
A leading researcher examining this question is Dr. Martha Belury of Ohio State University. At the CLA Summit 2007, she provided a window on the latest knowledge, as part of a presentation on "The role of adipokines in effects of CLA on insulin resistance."
Delivering an overview of key research findings, including from several from her own studies, Belury recapped the strong promise CLA has shown as a fat reducer. She also provided insights into the mechanisms and consequences of this activity.
"We now know that CLA does reduce fat in multiple animal models, including some studies in humans," says Belury.
Research shows the specific isomer CLA 10,12 is the type responsible for fat reducing effects, says Belury. Mice are most pronounced in their responses to CLA 10,12; rats typically show some body fat reduction though not as significant; and human studies, though limited in number and scope, have shown links between CLA 10,12 and fat reduction.
Ongoing research is aimed toward understanding the mechanisms of CLA as a fat fighter, says Belury. "It appears CLA is working in part through either indirect or direct effects on inflammation and metabolism. Indications are some of those effects are in adipose (fat) tissues and those effects also then indirectly effect surrounding tissues. CLA's influence on gene expression also likely plays a role."
A key research focus is examining the role of proteins and hormones produced by fat cells. One of area of progress is learning more about CLA's effect on leptin – a peptide hormone produced by fat cells that plays a role in body weight regulation by acting on the hypothalamus to suppress appetite and burn fat stored in adipose tissue. A second protein secreted from adipose, known as adiponectin, is also severely reduced in mice fed CLA 10, 12. The loss of adiponectin further exacerbates insulin resistance and inflammation in mice fed CLA 10,12. Future studied aimed to sustain adiponectin levels while still reducing adipose mass are underway in Belury's lab.
Another important aspect pursued by Belury and colleagues is the effect of CLA on lipodystrophy, a problem known to occur under several conditions of disease and drug treatment of disease. Lipodystrophy occurs when adipose tissue builds up in areas it normally shouldn't, such as in the liver and other major organs.
In studies with mice, CLA 9,11 has been shown to have an anti-inflammatory effect that may mitigate lipodystrophy, while CLA 10,12 has been shown to move fat away from adipose tissue and into these abnormal areas.
"It may be that we need to look at ratios of CLA 9,11 and CLA 10,12 other than 1:1, to find the combination that results in the best effect," says Belury. "There may be other effective approaches to combine CLA 10,12 with anti-inflammatories."
A key aspect of the lipodystrophy research along with the broader research effort related to CLA effects is the examination of the role of adipokines - the proteins secreted by fat cells. A major focus of the adipokines research is its role in the effects of CLA on insulin resistance.
Belury citied findings from other researchers showing CLA 9,11 significantly reduces insulin resistance, while results with CLA 10,12 are mixed.
The knowledge harvested from ongoing research into adipokines will provide a base of information from which strategies for best use of CLA may be developed.
Related to the CLA insulin resistance research, Belury and colleagues are pursuing a new study to examine the effects of CLA supplementation on people with type II diabetes.
Reprintable with credit. Individual articles in the Report on CLA Summit 2007 are available for reprint, with acknowledgement of the source: The CLA Network. For broader reprint requests or reprint assistance contact the CLA Network at CLAnetwork@gov.ab.ca.
