Research indicates CLA may have considerable benefits for human health, including the prevention and reduction of several chronic diseases, says Dr. Spencer Proctor.
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Dr. Spencer Proctor
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The over-arching goal of the CLA Network's human health module has been to increase knowledge of the human health importance of naturally derived CLA, says Dr. Spencer Proctor, Director of the Metabolic and Cardiovascular Diseases Laboratory at the University of Alberta.
"This has been a modest initiative, but we've seen some strong achievements," says Proctor, leader of the module. "The module's initial focus has been to lay the required research groundwork to provide a basis for further research in all modules of the CLA Network. The results to date have been very encouraging, which bodes well for our future efforts."
Though CLA human health research is in early stages around the world, pioneering studies based largely on animal models have shown CLA has considerable potential for human health benefits related to cancer, heart disease, diabetes, kidney disease, bone density and obesity.
Research by the CLA Network human health module has helped to both confirm important links to health benefits and supply new knowledge to further support and understand those links, says Proctor, who presented a summary of module progress at the CLA Summit 2007 conference.
A key thrust for the module has been to look at many different CLA types (isomers) and determine which health outcomes or benefits each different structure may have.
The most dramatic area of CLA human health research has been cancer treatment and prevention, says Proctor. In a series of cell culture studies, researchers participating in the CLA Network have confirmed specific types of CLA can reduce the proliferation of cancerous cells. "Both key isomers demonstrated anti-cancerous potential in a number of studies," says Proctor.
The most striking results were obtained in the preliminary studies using a type of human breast cancerous cells known as MCF-7. These are estrogen receptor positive cells and are used as a model to represent one of the common forms of cancer that women get. In these studies, CLA isomers inhibited cell growth by approximately 33 percent with CLA 9,11 and by 39 percent with CLA 10,12. "Several other human cells are being studied and the mechanisms underlying these results are now being explored," he says.
These and other achievements were realized using a cancerous cell line developed by the CLA Network as a model for anti-proliferative bio-activity.
Progress has also been made to uncover beneficial effects of CLA on obesity associated inflammation. Module studies using an obese rat model have identified a pro-inflammatory state that occurs during obesity. They have also indicated that CLA decreases inflammatory-related production of nitric oxide.
"Obesity itself is now often thought of as a pro-inflammatory state," says Proctor. "Our research has served to validate findings that CLA may help mitigate this state."
Additional research has focused on CLA effects on cardiovascular disease and insulin resistance. Using a new rat model they developed to examine inflammation during cardiovascular disease and insulin resistance, module researchers identified numerous positive effects of mixed isomers of CLA. These positive effects included weight loss, improvements in lipid metabolism related to cardiovascular disease risk factors and reduction of insulin sensitivity. Researchers also identified dramatic effects of reduced kidney disease.
"This research indicated strong multi-benefits of CLA to assist with a number of human health issues," says Proctor.
Recent and ongoing work includes: Further focus on using the new rat model to examine CLA effects on obesity, cardiovascular disease and insulin resistance; long-term animal feeding trials using CLA-enriched butter oil extract; and acute animal feeding trials using a pure form of the CLA precursor vaccenic acid, which is known to be converted into CLA 9,11 once consumed.
Several key results have already been achieved in these areas. Studies with the new rat model have further indicated potential CLA benefits related to early type II diabetes and metabolic syndrome. Enriched butter oil studies have shown some beneficial effects on lipid metabolism following "fat challenge" - an induced boost in triglycerides and chylomicrons – as well as continued reduced kidney disease.
Research with vaccenic acid has been particularly encouraging, says Proctor. There has been little data about natural trans fatty acids, including vaccenic acid, but now module researchers have produced the first evidence that high vaccenic acid enriched butter oil may confer some health benefit.
"This is very significant because vaccenic acid is often the highest single trans-fatty acid in dairy and beef products," says Proctor. "This is further evidence that can help change the negative image associated with animal fats. In this context, we are hoping to initiate clinical studies that will yield yet another milestone for the CLA Network."
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.
