A Quick Guide to CLA (Conjugated Linoleic Acid)
By Dr. Michael Murray
In this article:
The nutritional supplement CLA (conjugated linoleic acid) is a unique form of the essential fatty linoleic acid that is showing tremendous promise in the promotion of good health. CLA is found naturally occurring in meat and dairy products when the cattle and cows consume a diet rich in grasses. Now that livestock is primarily grain-fed, the CLA has virtually disappeared out of dairy products and the meat we consume. As a result, that may have contributed to an increased risk for obesity, heart disease, and even cancer.
CLA was discovered in 1978 when Michael Pariza, Ph.D., and other researchers at the University of Wisconsin were seeking to find possible cancer-causing compounds in meat. Instead, they found a potential anticancer compound - CLA. In preliminary animal and test-tube studies, CLA has shown evidence that it might reduce the risk of cancers at several sites, including breast, prostate, colorectal, lung, skin, and stomach. Whether CLA will produce a similar protective effect in humans has yet to be determined, but researchers are optimistic.
Over 200 studies have shown that CLA may play a very important role not only against cancer, but also in helping fight diabetes, obesity, and hardening of the arteries (atherosclerosis). Particularly exciting for many, is the research showing that CLA supplementation can help promote weight loss.
Researchers believe that CLA helps block fat cells that are in the body from filling up with fat by interfering with a fat-storing enzyme known as lipoprotein lipase as well as by increasing the sensitivity of cells to the hormone insulin. CLA is also believed to help burn fat by revving up muscle metabolism and helping increase lean muscle mass. The more muscle you have, the more calories your body uses in order to function, thereby speeding up the fat-burning process.
In one clinical trial, researchers from the University of Wisconsin recruited 80 obese people and had half of them take 3,000 mg of CLA daily, while the other half took a placebo. They were all put on a diet program and encouraged to exercise. Weight loss was about the same for both groups, an average of 5 pounds. So, why take CLA? Those taking CLA reported less fatigue, dizziness and nausea than those on the placebo. But, the real advantage was while the people taking the placebo put the weight back on mainly as fat the people taking CLA who put weight back on put it on primarily as lean muscle and not fat. In other words, CLA promoted an increase in lean muscle mass and a decrease in the percentage of body fat. Similar results were found in a study conducted at Lund University in Sweden.
In one study from the University of Sweden, CLA supplementation was shown to help prevent the regaining of body fat after weight loss. The study was a one-year continuation of the original 12-month, double-blind, placebo-controlled study of 180 overweight subjects. In the first year, subjects were randomized in one of three groups: placebo (olive oil), or CLA. In the second 12-month phase of the study, all subjects took CLA supplements as triglycerides. CLA supplementation prevented subjects in the two CLA groups from regaining the 8 percent of body fat they lost in the first year. The participants that had been on the placebo the first year and then took CLA for 12 months experienced a 5 percent reduction in body fat.
Several studies have shown CLA can help people lose weight and not just prevent a yo-yo effect of gaining back the lost weight. For example, in a study conducted in Taiwan in twelve weeks of supplementation CLA (3,000 mg daily) and no diet or exercise plan, CLA produced a 1.5-pound weight loss, a total fat mass loss of 1.25 pounds, and -0.58% drop in body fat percentage. When the data was examined in heavier subjects (i.e., BMI greater than 27), CLA produced even more significant changes. Women also tended to respond better to CLA supplementation in terms of greater total fat mass and fat percentage drops than males.
The recommended dosage is 1,000 three times daily with dosages up to 6,000 mg per day considered safe. To get the 3,000 mg of CLA from dietary sources only is not possible. A person would have to eat about 5.81 pounds of fresh ground beef, 53 ounces of American cheese or 1.73 gallons of vanilla ice cream. Fortunately, CLA is available as a nutritional supplement. However, not all CLA is the same or clinically proven. In order to be effective, the CLA must have a 50:50 ratio of two very important forms of CLA. The Clarinol and Tonalin brands of CLA both have this proper composition and have proven positive clinical results.
No side effects or drug interactions have been reported with CLA supplementation. Since the effects of CLA during pregnancy and lactation have not been sufficiently evaluated, it should not be used during these times.