L-Carnitine for Sports & Fitness

Also known as: Propionyl-L-Carnitine

What is it?

L-carnitine is made in the body from the amino acids lysine and methionine, and is needed to release energy from fat. It transports fatty acids into mitochondria, the powerhouses of cells. In infancy, and in situations of high energy needs, such as pregnancy and breast-feeding, the need for L-carnitine can exceed production by the body. Therefore, L-carnitine is considered a "conditionally essential" nutrient.¹

Where is it found?

Dairy and red meat contain the greatest amounts of carnitine. Therefore, people who have a limited intake of meat and dairy products tend to have lower L-carnitine intakes.

Why do athletes use it?*

Some athletes say that L-carnitine

improves athletic performance.

What do the advocates say?*

This is a good supplement to take if you exercise, particularly if you participate in endurance activities, such as running. It helps with transporting fatty acids into the mitochondria, so L-carnitine may make exercise more productive, particularly among obese people.

How much is usually taken by athletes?

L-carnitine, which is normally manufactured by the human body, has been popular as a potential ergogenic aid (i.e., having the ability to increase work capacity), because of its role in the conversion of fat to energy.² However, while some studies have found that L-carnitine improves certain measures of muscle physiology, research on the effects of 2 to 4 grams of carnitine per day on performance have produced inconsistent results.³ L-carnitine may be effective in certain intense exercise activities leading to exhaustion,⁴ but recent studies have reported that L-carnitine supplementation does not benefit non-exhaustive or even marathon-level endurance exercise,⁵ ⁶ anaerobic performance,⁷ or lean body mass in weight lifters.⁸

Are there any side effects or interactions?

L-carnitine has not been consistently linked with any toxicity.

The body needs lysine, methionine, vitamin C, iron, niacin, and vitamin B6 to produce carnitine.

Are there any drug interactions?
Certain medicines may interact with L-carnitine. Refer to drug interactions for a list of those medicines.

Resources

See a list of books, periodicals, and other resources for this and related topics.

*Athletes and fitness advocates may claim benefits for L-carnitine based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles on L-carnitine. For more complete and detailed information, including references and safety information, see L-Carnitine as a nutritional supplement.

References
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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.

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