Helen Bishop MacDonald

"Since CLA became known to the scientific and health community my concern has been that even if CLA were absolutely proven to prevent cancer, which it may very well, we would have a difficult time getting health professionals and consumers on board," says MacDonald. This is because of the mindset about ruminant fats, which she says can be summed up in two words: "They're bad!"

But the battle of perception need not be lost, says MacDonald, who offered insight into the ruminant fats debate in a keynote presentation at the CLA Summit 2007. There's a growing body of evidence that ruminant fats have been unfairly maligned and in fact are often health promoting. CLA is a leading example of a good fat found naturally in dairy and beef products that has been linked to considerable potential for human health benefits.

That's why a key benefit of CLA research is its role in providing knowledge to help rehabilitate the image of animal fats, she says. "CLA can play a major role in reshaping the negative image of animal fats. It's a great example that many of these fats are not harmful but in fact are healthful."

Exploding the myths

Among the myths that have persisted around ruminant fats is the notion that these fats cause heart disease, notes MacDonald. But close examination of the research reveals substantial evidence to the contrary. She cited numerous studies supporting her conviction that animal fats don't cause heart disease and more typically either have no negative effect or are associated with health promotion.

"We need to pay attention to the fact that we may have been barking up the wrong tree by targeting animal fats," says MacDonald.

In fact, the targeting of animal fats may very well be a "red herring" that has distracted attention from much more likely causes of health concern, she says. One major concern is man made hydrogenated fats, which contain trans fats. Another concern is excess intake of linoleic acid.

It's important not to confuse linoleic acid with conjugated linoleic acid (CLA), since these are two different fatty acids. Linoleic acid is a type of omega-6 fatty acid that is an essential fatty acid beneficial to human health. However, emerging studies indicate that when linoleic acid is consumed at very high levels this can upset the desired healthy ratio of omega-6 to omega-3 fatty acids. The greatest source of linoleic acid in the human diet is vegetable oils.

"In the early 1900s if your great, great grandmother was going to make a cake, she didn't use vegetable oils; she used butter," says MacDonald. "If she were going to make a pie she used lard. Our intake of trans fats and linoleic acid has gone up considerably since that time."

A natural advantage

Ruminant fats contain trans fats but a growing body of research indicates these natural forms are not harmful and may be beneficial, she says. The real culprits are man-made trans fats, which have been shown to raise bad cholesterol and lower good cholesterol.

Regarding disruption to the omega-6 to omega-3 ratio, studies have indicated this imbalance may enhance carcinogen induced mammary and pancreatic cancer in rodents and may also enhance colon cancer in rodents. One study noted that linoleic acid is the only fatty acid to exhibit an unequivocal cancer enhancing effect.

"About sixty years ago the ratio of omega-6 to omega-3 was about two to one. Today the ratio is 25 to 1 and we've seen cancer rates increase."

By comparison, research exonerating animal fats continues to grow, says MacDonald. Among the most recent research are studies indicating that ruminant fats, including saturated and trans fats, have no adverse affect on lipid profile and may have a beneficial effect on the size of low-density lipoproteins (LDL "bad" cholesterol).

"LDL particle size is now getting to be one of the big issues in research on heart disease. This is one example of more and more findings that show animal fats have gotten a bad rap."

Reprinted courtesy of the CLA Network. 'www.CLAnetwork.com'

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