“CLA (conjugated linoleic acid) is a naturally occurring fatty acid found mainly in the fat of dairy products and meats such as beef and lamb. … CLA has been found to have numerous beneficial health effects. It acts as an antioxidant. It helps maintain a healthy heart and veins, and healthy cholesterol and triglyceride levels. It combats atherosclerosis. It encourages the buildup of muscles and helps prevent weight gain. Preschoolers who have an optimal intake of CLA i the diet are less likely to suffer from asthma when they are older. But, perhaps the most impressive feature, is that CLA is the only known fatty acid to have strong anticarcinogenic properties. CLA has been shown to inhibit the growth of a variety of human tumor cells, including cancer cells of the skin, colon, heart, and lung. Also, animal studies showed that CLA prevents the spread of cancer.
Australian studies published by the American Society for Nutritional Sciences showed that CLA inhibited the proliferations of malignant melanomas as well as colorectal, breast, and lung cancer cell lines. In mouse studies, CLA reduced the incidence of chemically induced epidermal tumors and forestomach neoplasia (the formation of new tissue). In rat studies, CLA reduced the incidence of aberrant crypt foci, which are precancerous.
Unfortunately, less than optimal amounts of CLA are consumed by Americans. There are several reasons: changes in agricultural practices, changes in dietary choices, and mixed messages from governmental agencies.
Cud-chewing animals (ruminants such as cows) have bacteria that convert linoleic acid in to CLA. However, the CLA content of the milkfat of cows and the CLA content of the fat in beef has declined steadily as the animals have been switched from grass grazing in pastures to grain feeding in feedlots. These changed practices yield greater volumes of milk from cows, and quicker weight gain in beef animals, at the expense of CLA and other beneficial components. Also, the feeding of dry hay in wintertime offers no CLA in the feed.
Due to changes in dietary choices, most Americans fail to consume adequate amounts of CLA. Many people select low-or non-fat milk and other dairy products, and avoid butter and cream. Many people also foolishly shun red meats or limit their intake and discard any visible fat in the meat.
Government agencies have been sending mixed messages. They have recommended reduction of saturated fats (sources of CLA) and have encouraged the substitution of vegetable oils (lacking in CLA). They have labeled trans fats as “bad” and fail to acknowledge that CLA, a trans fat, is beneficial. The FDA had wrestled with this problem, when it formulated a regulation mandating food manufacturers to indicate the trans fats in food products. The agency considered exempting CLA from the regulations, but decided it would be too confusing for the public.
Beef and lamb fat also contain another fatty acid, palmitoleic acid. This substance protects humans from viruses and other pathogens. These various findings should arouse some curiosity in scientists. The time has come to reexamine the commonly held belief that butter, cream, whole milk, and animal fats should be limited or avoided.” pg. 165-66, Probiotic Foods for Good Health: Yogurt, Sauerkraut, and Other Beneficial Fermented Foods