Conjugated linoleic acid, or CLA, is an isomer of linoleic acid -- an essential fatty acid. An isomer is a compound with the same composition, but different shape. There are two sources of CLA. The first is meats from ruminant animals and their byproducts such as milk and cheese. The other is supplements, which are purported to enhance physical performance. Consult a health care professional before adding CLA to your regimen.
Importance of Weight-Training
According to the Centers for Disease Control and Prevention, one in every three Americans age 65 and older falls every year. Falls and accidental injuries cause fractures, traumas, hospitalization, higher death risks and healthcare costs. The most probable cause of falls is sarcopenia, or loss of muscle mass. Sarcopenia involves oxidative stress, reduced protein synthesis, lower hormone levels and loss of motor neurons. Losing motor neurons -- nerve cells that stimulate muscle movement -- causes muscle fiber loss, atrophy, frailty and poor balance.
Conjugated Linoleic Acid
One way of reducing risk for falls is weight training. A study published in a 1999 issue of the "Journal of the American Geriatric Society" found that resistance training once or twice a week improves muscle strength in older adults.
Aging is associated with muscle loss and increased fat mass. CLA supplementation may help reverse this process, according to a long-term trial published in the 2004 issue of "The American Journal of Clinical Nutrition." The trial found that CLA supplementation reduced body fat in healthy but overweight adults.
Another study, published in a 2007 issue of "The British Journal of Nutrition," reported that CLA supplements reduced body fat in the legs of overweight and obese adults.
CLA and Weight Training
Enhanced athletic performance and changes in body composition attributed to CLA may not be as apparent in well-trained athletes as they are in sedentary individuals, say M.A. Tarmopolsky and A. Sadfar, authors of a 2008 review published in "Applied Physiology, Nutrition, and Metabolism." The review reports that only two studies demonstrate the effects of CLA on weight training. The first study, published in a 2002 issue of the "Journal of Strength and Conditioning Research," found CLA supplements did not appear to have performance-enhancing effects in resistance-trained athletes. The second trial, published in a 2006 issue of "Medicine and Science in Sports and Exercise," found that CLA supplementation and resistance training resulted in small body composition changes, including enhanced muscle mass and lower muscle protein loss.
Tips and Precautions
Consult your doctor before using CLA, especially if you are pregnant, breastfeeding, have high blood pressure, high lipid levels, cardiovascular disease, diabetes or metabolic syndrome.
Include grass-fed beef, lamb and dairy products in your diet. Grass-fed beef contains 1.23 g of CLA per 3.5-oz. serving, compared to 0.48 g of CLA per 3.5 oz. of conventional beef. The CLA in these foods consists mainly of cis 9 trans11 CLA. In contrast, supplemental CLA contains cis 9 trans11 CLA and cis 12 trans10 CLA. Cis trans 10 CLA has been found to increase oxidative stress and inflammation, which increases the risk for heart disease.
References
- "The American Journal of Clinical Nutrition"; Conjugated Linoleic Acid and Disease Prevention: A Review of Current Knowledge; Helen B. MacDonald; April 2000
- Centers for Disease Control and Prevention: Falls Among Older Adults: An Overview; December 2010
- "Journal of the American Geriatric Society"; Once Weekly Resistance Exercise Improves Muscle Strength and Neuromuscular Performance in Older Adults; D.R. Taafe et al.; October 1999
- "The American Journal of Clinical Nutrition"; CLA Supplementation for 1 Year Reduces Body Fat Mass in Healthy Overweight Humans; J.M. Gaullier et al.; June 2004
- "The British Journal of Nutrition"; Six Months Supplementation with Conjugated Linoleic Acid Induces Regional-Specific Fat Mass Decreases in Overweight and Obese; J.M. Gaullier et al.; March 2007
- "Applied Physiology, Nutrition, and Metabolism"; The Potential Benefits of Creatine and Conjugated Linoleic Acid as Adjuncts to Resistance Training in Older Adults; M.A. Tarmopolsky & A. Sadfar; February 2008
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