CLA Could Spell Success
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Component of milk found to have huge potential health benefits.
It happens time and time again at meetings. Dairy farmers raise the issue about putting more effort into looking at one of milk's health benefits and developing it commercially. Well, one component of milk has potential benefits for not just one but many aspects of human health.
Conjugated Linoleic Acids (CLAs) are produced naturally by and are pretty much unique to ruminants. There are 18 different forms of CLAs in milk. One is a potent anti-cancer compound. In studies with rats, this CLA has been found to be effective in killing mammary and prostate cancer cell lines. More recently, it proved effective with human mammary cancers. Other forms of CLAs have important health effects relating to diabetes, and fat and muscle metabolism.
The health implications of CLA in milk have prompted intense research investigation. A large number of research papers and at least two invited symposiums at this year's American Dairy Science Association meetings dealt with various aspects of CLA. Dr. Michael Pariza, a University of Wisconsin researcher, keeps an updated reference list on the Internet of published CLA research. At last check that list was more than 12 pages long. It includes lots of work across Canada at major agricultural research institutions.
To profit from this wonderful milk component, we need to understand what it is, whether we can improve CLA levels and how we might market it in finished products. Here's a primer on some key points we've discovered about CLAs so far:
CLAs were actually discovered by researchers investigating the reputed bad effects of saturated fatty acids in beef. Fat produced by ruminants, whether in meat or milk, tends to have a high percentage of saturated, or hard, fats. A portion of the fats, however, are unsaturated, or soft, fats.
These soft fats are the CLAs. Found in milk and meat, all have 18 carbon atoms (C18) and two double bonds. They get twisted into different shapes and the bonds go in different places. This gives them unique chemical properties.
Milk's CLA content varies and can range from 2.5 up to 18 milligrams per gram of fat. The usual range is 4.5 to 5.5 mg (0.45 to 0.55 per cent). So, if milk is 3.5 per cent fat, then its CLA content is between 0.01 and 0.025 per cent.
One study, by the University of Alberta's Dr. John Kennelly, reported that the base line level of CLA in the human diet ranges from 52 to 137 mg per day. The beneficial effect of CLA in the human diet is believed to be up to a level of three grams per day. We wouldn't have to change our diet or eating habits much to consume that amount. For example, a serving each of whole milk, a sandwich with butter and cheddar cheese, all made with high-CLA milk, would provide about 1.5 grams.
Feeding trials with total mixed ration (TMR) diets versus pasture feeding with Jerseys and Holsteins have shown Holsteins were higher for some CLAs and Jerseys were higher for saturated fats. Some Australian studies have also concluded that a higher level of milk fat is associated with higher levels of saturated fats and lower levels of unsaturated fats.
A South Dakota researcher reported breed differences among cows consuming fat-enhanced feed designed to increase CLA in milk. When fed a combination of fish oil and extruded soybeans, Holsteins produced 42 per cent more CLA than did Brown Swiss cows.
Researchers in California have concluded that differences among and within dairy breeds indicate genetic selection may be a valid way to alter levels of CLA produced in milk. Feeding trials where CLA levels have been measured show large differences among the cows being studied. Results of the California research should be released this winter. However, identifying genetic parameters for CLA and other fatty acid content currently means costly lab analysis.
It's believed CIA is made in the mammary gland from some of the breakdown products from the action of rumen bacteria. One enzyme seems to playa key role in this process. Work is being done to identify genes that control this enzyme as one way of possibly improving CIA levels.
Nutrition is the main environmental factor that affects milk fat composition. It's a logical place to alter fatty acid composition and CLA levels. A large number of feeding trials have been carried out or are ongoing in Canada and the U .S.
Pasture feeding has been shown to increase CLA concentration over TMRs containing stored forage and concentrate. Irish research has shown a two to three-fold increase with pasture feeding. Adding rapeseed at the rate of 660 grams per day of oil per cow further increased CLA by 50 per cent in Irish studies.
Sunflower oil, linseed oil and soybean oil have all been used to increase CLA levels of up to five times the base line levels. Calcium salts of oils from canola, soybean and linseed for rumen bypass were used at Cornell University to give a five to seven-fold increase.
Supplementation with fish oil has also been shown to increase CLA content of milk. It's thought that the oil results in more products for use in the mammary gland to make CLA. The end result is mostly the form of CLA that acts as an anti-cancer compound.
Commercially prepared synthetic CLA tends to have a wider range of CLA forms, mainly the type that have a greater effect on fat metabolism. Feeding calcium salts of this CLA to cows in most cases has caused milk fat depression, lowered milk fat percentage, lower fat yield and in some cases lower milk yield.
The concentration of CLA in this milk has been increased but overall the quantity has not gone up due to the lowered overall milk fat. This form of synthetic CLA, due to its inhibitory effect on fat synthesis, may be useful in altering fat-protein ratio in milk.
It's obvious that possible health benefits offer niche market potential for high-CLA milk and products made from it. Some consumer acceptance surveys have already been done with positive results.
However, high-CLA milk looks much like regular milk. Among the challenges are to have economical testing and monitoring methods to identify high-CLA milks and herds. The product must then be processed, and a marketing stream set up to brand the product and sell it so that returns are worthwhile for producers and processors.
CLAs could be a wonderful success story for dairy products. We just need to apply our known technologies to develop and market them. As an added benefit, CLAs even contribute to making softer butter.
This article appeared in the November 2001 Ruminations column of the Ontario Milk Producer magazine.
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