June 29, 2008

Acetyl-L-carnitine, also known as L-carnitine, is an amino acid derivative that is synthesized from methionine and lysine, both of which are essential amino acids. Acetyl-L-carnitine can be found in almost all the human body’s cells and Acetyl-L-carnitine is mainly located in cardiac and skeletal muscles. Acetyl-L-carnitine is produced in the kidneys and liver and is also absorbed in the small intestine during digestion. This amino acid derivative is an essential nutrient, which means at certain times the body may require a higher level of Acetyl-L-carnitine than it is capable of producing. This also means that Acetyl-L-carnitine should be obtained daily in the form of a dietary supplement or from dairy products and meat. Very low amounts are usually found in plant products, however, there are a few exceptions.

When exercising, Acetyl-L-carnitine allows the body to spare its glycogen stores in the muscle by increasing the break down of fat. Glycogen is a carbohydrate that is typically stored in muscle tissue. It is also used in the body as an energy source and plays an important role in the way an individual performs while exercising. The depletion of glycogen in the muscle is the main cause of fatigue during exercise. Acetyl-L-carnitine also prolongs one’s ability to exercise, by increasing the body’s fat burning potential. In athletes, high Acetyl-L-carnitine levels increase their ability to train and increase their endurance so that they are able to perform longer. In addition, people trying to lose weight, like athletes who are involved in weight restricted sports, must also consider the fat burning potential of Acetyl-L-carnitine.Â

One study was published that evaluated the long and short term effects of Acetyl-L-carnitine in female and male athletes who were medium/long-distance runners, swimmers, kayak-canoers, rowers, and weightlifters. The results of this study showed changes in Acetyl-L-carnitine urine, blood, and fatty acids levels, in addition to an accumulation of lactic acid after exercise. The increase in Acetyl-L-carnitine levels also led to an increase in fatty acid levels and endurance. As a result of this study Acetyl-L-carnitine is recommended as a supplement that helps elite athletes increase their strength and endurance.

Acetyl-L-carnitine also has antioxidant properties that protect cells and strengthen the immune system. A study performed with rats showed that Acetyl-L-carnitine could reverse damage to the immune system and cell damage after the rats were giving a cancer drug. The results showed that Acetyl-L-carnitine can be used to prevent, treat, or reverse free radical damage. Research shows that Acetyl-L-carnitine also protects the cardiovascular system. Acetyl-L-carnitine lowers triglyceride levels and raises high-density lipoprotein (HDL) cholesterol and by doing so reduces the risk for developing heart disease. Additional benefits of consuming Acetyl-L-carnitine is its ability to reduce the signs of aging, strengthen skeletal muscle and stimulate enhanced brain function. In the skeletal muscle Acetyl-L-carnitine fights ailments caused by stress and prevents physiological decline. Research that is ongoing shows that Acetyl-L-carnitine may also prevent the onset of Alzheimer’s disease and strokes. Recent studies have demonstrated the positive effects that Acetyl-L-carnitine has on men’s reproductive systems by increasing sperm count. It also treats pain, stimulates nerve regeneration, and vibratory perception in chronic diabetic neuropathy patients.

One further note of caution is that athletes should not take Acetyl-L-carnitine in the D carnitine form or the D, L carnitine form, which is a combination of D-carnitine and L-carnitine. Supplements that contain D-carnitine have been shown to be toxic and have been banned by the Food and Drug Administration (FDA) in the United States.


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Dragan IG, V. A. (1989). Studies concerning chronic and acute effects of L-carnitina in elite athletes. Physiologie., 26 (2), 111-29.

Sener G, E.-D. E. (2006). L-Carnitine ameliorates methotrexate-induced oxidative organ injury and inhibits leukocyte death. Cell Biol Toxicol., 22 (1), 47-60.

Shapiro, M. J. (2004). The Effects of Acetyl-L-Carnitine Supplementation. Retrieved June 24, 2008, from Innovative Delivery Systems:

Sima AA, C. M. (2005). Acetyl-L-carnitine improves pain, nerve regeneration, and vibratory perception in patients with chronic diabetic neuropathy: an analysis of two randomized placebo-controlled trials. Diabetes Care , 28, 89-94.


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