Vitamins, Minerals and Dietary Supplements
What is CLA? Why do we need it?
CLA stands for conjugated linoleic acid. It's a slightly different version of an essential fatty acid (linoleic acid), and is found in dairy products. In humans, it is produced from linoleic acid by bacteria that live in the intestinal tract.
At present, scientists are unsure exactly what type of protective effects CLA has. Animal studies have shown that CLA supplements can reduce the risks of certain types of cancers, including cancer of the breast, prostate, lung and stomach; these studies have yet to be conducted in humans, however. Other research suggests that CLA can reduce body fat in people who exercise regularly, but not body weight.
How much CLA should I take?
At present, the appropriate amount of CLA to be taken on a daily basis has yet to be determined. Most animal studies have used large amounts, equal to several grams per day for humans; the abovementioned body fat study used a dose of 4.2 grams of CLA per day for four weeks.
What forms of CLA are available?
CLA is produced in the body by intestinal bacteria, which convert linoleic acid to CLA when needed. CLA can also be found in many dairy products, such as eggs, milk and cheese, along with beef, chicken and corn oil.
What can happen if I take too much CLA? Are there any interactions I should be aware of? What precautions should I take?
Because CLA is not an essential nutrient, average daily dosage levels and maximum recommended intake levels have yet to be determined. As if this writing, the side-effects of CLA in humans have not been determined in any published studies, nor are there any known interactions with drugs. However, an unpublished study from 1997 noted an increased incidence of gastrointestinal problems in people taking large amounts of CLA. As always, make sure to consult with a licensed health care provider before taking CLA or any other dietary supplement or herbal remedy.
- Ferreira M, Krieder R, Wilson M. Effects of CLA supplementation during resistance training on body composition and strength. J Strength Conditioning Res 1998;11:280.
- Nicolosi RJ, Rogers EJ, Kritchevsky D, et al. Dietary conjugated linoleic acid reduces plasma lipoproteins and early aortic atherosclerosis in hypercholesterolemic hamsters. Artery 1997;22:266-77.
- Riserus U, Berglund L, Vessby B. Conjugated linoleic acid (CLA) reduced abdominal adipose tissue in obese middle-aged men with signs of the metabolic syndrome: a randomized controlled trial. Int J Obes 2001;25:1129-35.
- Thom E. A pilot study with the aim of studying the efficacy and tolerability of tonalin CLA on the body composition in humans. Lillestrom, Norway: Medstat Research Ltd., July 1997. Unpublished.
- Thompson H, Zhu Z, Banni S, et al. Morphological and biochemical status of the mammary gland as influenced by conjugated linoleic acid: implication for a reduction in mammary cancer risk. Cancer Res 1997;57:5067-72.