Dr. Michael Pariza at the University of Wisconsin first discovered the nutrient called Conjugated Linoleic Acid (CLA), in grilled ground beef. Ironically, he and his colleagues had been looking for cancer-causing substances in red meat. Instead they found CLA, an apparently health-promoting polyunsaturated fatty acid that seems to reduce mutagenic—that is, precancerous-changes in bacteria as well as to decrease cancer risk in mice exposed to tobacco-derived carcinogens.
Subsequent work strongly suggests that CLA supplements may have similar benefits in humans, plus bolster immunity, serve as a glutathione-boosting antioxidant, decrease insulin resistance, reduce body fat, and perhaps even increase muscularity.
What are food sources of CLA?
The isomer scientists say that CLA can be produced artificially by heating linoleic acid, an essential nutrient contained in animal fats and plant oils, in the presence of a base. However, the stomach bacteria of plant-eating animals such as cows, lamb, veal, and turkey also produce CLA in a natural fashion.
This brings up an intriguing point about the modern food supply. These days most livestock in America is corn-fed. But not that many decades ago most livestock in the U.S. was instead grass-fed, which means that the nutritional composition of the meat we consumed was notably richer in various nutrients, notably such fatty acids as omega-3 and CLA. (The old saying “You are what you eat” also applies to cows.) In particular, grass-fed animal flesh contains roughly five times as much CLA as does the flesh of corn-fed animals. Those same numbers also hold true for the CLA content of milk and cheese produced by grass-fed dairy cows versus corn-fed dairy cows.
Unfortunately, consumers often have difficulty finding—much less affording—meat from free range, grass-fed animals. Many health-conscious people now use CLA supplements to help close this nutritional gap.
What does CLA do?
Rats fed diets containing 1.5% CLA by weight appear to have a total decrease in the number of breast-cancer tumors by over half, outstripping the protective effects of vitamin E.5 Scientists have also noted that in rodents CLA seems to reduce the development of both benign and malignant tumors of the lung, colon, and prostate.
Other animal research points toward the immune-boosting effects of CLA, perhaps by down-regulating the production of certain immune-suppressing compounds called leukotrienes and prostaglandins. Also, CLA seems to further improve immunity by enhancing insulin sensitivity. (Keep in mind that overly high insulin levels lead to a reduction in immune system sensitivity, one of many good reasons to control body fat.)
Studies conducted by Drs. Watkins and Seifert show that rats and chicks fed high-CLA butterfat have more bone growth and strength than animals fed other fats. They theorize that CLA’s ability to block excess production of an inflammatory substance called PGE2 contributes to the improvement in bone quality.
But while such things as immunity, cancer prevention, and bone health are extremely important, the one characteristic of CLA that has most captured the public’s imagination is its considerable potential for weight control and body fat reduction. The best research in this area seems to have been conducted in the Scandinavian countries. At Uppsala University in Sweden half the members on one study given 4.2 grams of CLA each for twelve weeks showed a significantly higher percentage of fat loss than the placebo group, which was fed an equivalent amount of olive oil. Norwegian researchers have had similar promising results with CLA: One of their studies showed up to a twenty percent reduction in weight—mostly abdominal fat—in middle-aged men who were given several grams of CLA per day versus the placebo and control groups.
Is it conceivable that the decline in the CLA content of the modern American diet has contributed to our current obesity epidemic, as well as to other health problems? Current research raises this disturbing possibility, but also shows the nutritional potential of CLA.
How is CLA taken?
On average, non-vegetarians in this country consume roughly one gram of CLA daily from beef, lamb, and dairy, the three best sources of this substance. Currently, research points toward an amount in the range of two to four grams per day as being in the range needed for CLA to have positive effects on immunity, weight control, and other health issues.
Typically, those wishing to see if they might benefit from CLA supplementation take three to six softgels per day, preferably with meals, in divided doses.
Remember that CLA is not a magic pill, but rather a nutrient the body uses to facilitate the metabolic process of burning fat in the body while possibly promoting lean body mass growth. Both of these actions can be part of losing weight and becoming a healthier person in general. Future studies on CLA involving more participants may prove to be very enlightening.
Is CLA safe?
Current research has so far shown no toxic effects from CLAat the amounts discussed, which are not that far removed from what someone might get either in a hunter/gatherer diet or in a diet rich in free-range meat. Those who take medications or have other health concerns should discuss this and all other supplements with their doctors before use.