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Long-Term CLA Study Shows 9 Percent Reduction in Body Fat and 2 Percent Increase in Lean Muscle

The first long-term Conjugated Linoleic Acid (CLA) study demonstrated the most significant reduction in body fat and increase in lean muscle taking TONALIN® brand CLA. The study’s results were presented at the American Oil and Chemist Society’s (AOCS) 94th Annual Meeting and Expo held in Kansas City, MI, in May 2003. The study results were also conveyed to attendees at SupplySide East held in Secaucus, NJ, in May 2003.

While short-term CLA studies with short supplementation periods have shown that CLA use improves body composition, there have not yet been any studies on CLA’s long-term effects until now. Jean-Michel Gaullier’s “Efficacy and safety of one-year supplementation with conjugated linoleic acid in moderate overweight” demonstrated that CLA reduced body fat by nine percent and increased lean muscle by two percent. The most remarkable effects on body composition were produced by trials performed with a mixture of the bioactive isomers (cis-9, trans-11 and trans-10, cis-12). Specifically, CLA generated a significant decrease in body fat, body weight and body mass index.

Overweight subjects were randomized in three groups, and supplemented for one year either with CLA given as free fatty acid, or as triglycerides, and compared with subjects taking a placebo (olive oil). Measurements performed with dual-energy X-ray absorptiometry show significant changes over time. Possible factors such as diet and training were also analyzed. In addition, the long-term safety of CLA was confirmed through rigorous recording of any side effects occurring during the overall study and analyses of blood parameters, including blood lipids and diabetes markers. Finally, records of the quality-of-life have been done in order to evaluate how CLA affected the daily life of the subjects included in the study.

CLA is a polyunsaturated, conjugated fatty acid that is a natural part of the human diet through its presence in meat and dairy products. The CLA content of natural dairy products has fallen over time, and the human body now needs to supplement its consumption of CLA from other sources.


Gaullier JM, Halse J, Hoye K, Kristiansen K, Fagertun H, Vik H, Gudmundsen O. Conjugated linoleic acid supplementation for 1 y reduces body fat mass in healthy overweight humans. Am. J. Clin. Nutr. 79(6):1118–1125 (2004 Jun).

Key concepts: cla, conjugated linoleic acid, body fat, lean muscle