Conjugated Linoleic Acid

It’s hidden in that pat of butter or sizzling burger. Consumers can buy it as a dietary supplement. And, if manufacturers achieve goals for GRAS approval, formulators will be able to include it in foods sometime in 2004. Conjugated linoleic acid (CLA) might fight against breast cancer, improve diabetes control, help curb body-fat gain and limit atherosclerosis.

In 1978, Michael Pariza, Ph.D., director and chair, Wisconsin distinguished professor, food microbiology and toxicology, University of Wisconsin, Madison, investigated the potential anticarcinogenic properties of hamburger. He isolated and during the next nine years identified the substance known as CLA, publishing his results in 1987 in Carcinogenesis. Today, hundreds of published papers discuss CLA’s various forms and potential health benefits.

This free fatty acid occurs in different isomeric forms, depending on the placement of double bonds between carbon atoms. The two varieties of CLA most widely studied are the cis-9 trans-11 (c9t11) and trans-10 cis-12 (t10c12) isomers.

Commercial CLA is commonly derived from safflowers and contains approximately a 50/50 mixture of c9t11 and t10c12 isomers with both di- and triglyceride forms available.

CLA occurs naturally in dairy or animal products, with the highest concentrations in products from ruminant animals, at a ratio skewed toward a predominance of c9t11 isomers.

Although difficult to document, researchers estimate that North Americans’ average consumption level of CLA has diminished over the last 50 years from approximately 3 grams to 1 gram per day, partially because CLA levels are higher in grass-fed or range-fed animals, and feed practices have shifted to grain in the United States. However, university research discovered that by manipulating a cow’s feed, it could produce milk with five times the normal levels of CLA.

Dale Bauman, Ph.D., Liberty Hyde Bailey professor, department of animal science and division of nutritional science, Cornell University, Ithaca, NY, using CLA-enhanced milk, has produced butter with 40 to 50 mg of CLA per gram of fatty acid — 800% to 1,000% more than regular butter. Bauman is publishing a paper in The Journal of Nutrition about his findings related to the anticarcinogenic properties of the fatty acid, vaccenic acid (11-octadeconoic acid), also present in butter. He says, “In a sense, butter is better than a pill, because you’re getting both CLA and vaccenic acid.”

Dairy-derived CLA has not emerged outside of the laboratory. Various dairy-industry representatives say that it is cost-prohibitive to modify the cows’ feed, and no plans to produce CLA-enriched dairy products exist.

The two isomeric forms, alone and combined, pose different health benefits. The 50/50 commercial blend impacts a person’s body mass index by reducing body fat while maintaining lean muscle mass, when ingested at a recommended daily intake level of 3 grams.

The c9t11 isomer is associated with anticarcinogenic properties, possibly providing benefits in all three stages of cancer — initiation, promotion and metastasis.

Pariza says, “Both isomers appear to be equally involved in cancer inhibition, apparently via different mechanisms. The typical commercial isomer mixture appears to be the best isomer ratio for health benefits.”

Today, only supplements — not foods — utilize CLA as an ingredient. CLA producers, such as Cognis, Loders Croklaan and PharmaNutrients, are all pursuing forms of GRAS status at this time.

Currently, sales for commercially produced CLA supplements focus on body composition. Research initiatives, however, are investigating other potential health benefits. The January issue of The Journal of Nutrition discusses a human study conducted by Martha Belury, professor of human nutrition at The Ohio State University, Columbus, that revealed the t10c12 CLA isomer impacted adult-onset (type 2) diabetes by lowering the subjects’ body mass as well as blood sugar levels.

Loders Croklaan Lipid Nutrition, Channahon, IL, is sponsoring three human clinical studies in different parts of the world to document CLA’s effect on the immune system. Although the studies are not final, according to David Lewis, business unit director, North America, results to date indicate that CLA acts as a passive immune response. “The body isn’t in high alert, but when a foreign substance enters in, such as the hepatitis-B vaccine we used, the participants who had received a four-week regimen of Safflorin (in free-fatty-acid form) prior to injection exhibited a stronger immune response than those who were on a placebo,” he explains.

One primary health benefit associated with the isomer blend is its role in reducing body fat. Heather Nelson Cortes, Ph.D., research scientist for Cognis Nutrition and Health, La Grange, IL, says that a consumer who takes the company’s Tonalin™ CLA as a supplement “won’t see the needle on the scale move dramatically, but they will feel healthier. The change we observe is that, combined with a proper diet and exercise, a person will more than likely see their clothing size drop down.”

A Norwegian human study found that CLA-supplemented subjects lost up to 20% of their body fat in three months without changing their diet.

“When looking at body composition as a primary benefit,” says Bill Froese, director of marketing at PharmaNutrients Inc., Lake Bluff, IL, “the natural use for CLA as an ingredient would be in those foods perceived to be somewhat healthy anyway, such as cereals, granola bars, yogurt or milk.”

Cortes agrees, adding, “I would think CLA would be very easy to incorporate into existing formulations, primarily in the functional-foods area.”

If FDA does award GRAS status, the number of applicable food categories could expand dramatically beyond functional foods. Lewis says the triglyceride form of CLA acts and tastes like any other commercial oil, such as sunflower. CLA, he says, is “perfectly stable, like any kind of an oil. Oxidation won’t be a problem if formulators minimize the light exposure and keep it sealed when not in use. It can basically replace soybean or any other type of oil, replacing one fat for a healthier alternative.”

Froese advises formulators to choose logical applications for CLA: “Sterol esters didn’t work because we put them into margarine. Consumers didn’t equate that with heart health.” He recommends formulating CLA into food that the consumer will relate to and that makes sense, such as “a ‘heart-happy’ food like oatmeal, which already can make a heart-health claim.”

Jeanne Turner is a freelance writer with more than 10 years of experience writing about the functional properties of food ingredients.