Carnitine (L-Carnitine)

Muscular activity depends on your body's ability to convert fatty acids into energy. Carnitine is an amino acid that is essential for this conversion. A typical daily diet contains 5 to 100 mg of carnitine. The body produces carnitine in the liver and kidneys and stores it in the skeletal muscles and heart, as well as in sperm and in the brain.

Some people can not properly use carnitine from their diet or suffer from dietary deficiencies of this nutrient. As a result, they may develop heart disease, skeletal muscle weakness, or low blood sugar. If you experience these symptoms and are found to have carnitine deficiency, your health care provider may recommend use of the supplement levocarnitine, or L-carnitine.

Uses

L-carnitine offers a variety of potential therapeutic uses, primarily related to the heart.

• Preventing heart disease
• Improving heart function in people with congestive heart failure
• Reducing heart damage when taken soon after a heart attack
• Reducing the pain of angina
• Treating cardiac arrhythmia (irregular heartbeat) without affecting blood pressure
• Reducing blood triglycerides and overall cholesterol levels while increasing HDL, or good cholesterol.

Your health care provider may also recommend taking L-carnitine if you have other health conditions, including the following.

• AIDS, especially to prevent side effects from the drug AZT
• Alcoholism
• Alzheimer's disease
• Anorexia
• Chronic fatigue syndrome
• Diabetes
• Down syndrome
• Epilepsy (childhood)
• Hemodialysis
• Immunosuppression
• Male infertility

Carnitine may also be recommended as a weight-loss aid.

Dietary Sources

Red meats are the primary dietary source of L-carnitine. Other animal-based foods containing

L-carnitine include fish, poultry, and milk products. Tempeh (fermented soybeans), wheat, and avocados also contain this nutrient.

Other Forms

Carnitine is available as a supplement in several forms. Only the L-carnitine forms are recommended. These include the following.

• L-carnitine (LC), which is the most widely available, is the least expensive, and has been studied the most
• L-acetylcarnitine (LAC), which appears to be best for Alzheimer's disease and brain defects
• L-propionylcarnitine (LPC), which may be best for angina and other heart problems

The D-carnitine form should not be used because it has produced undesirable side effects.

Certain L-carnitine products have been approved by the U.S. Food and Drug Administration for medical use and are available only with your health care provider's prescription. Others are sold as supplements and should not be used to treat serious carnitine deficiency.

How to Take It

Recommended doses of L-carnitine vary depending on the health condition being treated. The following list provides guidelines for the most common uses.

• To improve fat metabolism and muscular performance: 1,000 mg to 2,000 mg usually divided into two doses
• For treatment of heart disease: 600 to 1,200 mg three times daily, or 750 mg twice daily
• For AIDS patients being treated with AZT: 6 g daily
• For treatment of alcohol-related deficiencies: 300 mg three times daily
• For treatment of male infertility: 300 to 1,000 mg three times daily

Precautions

L-carnitine is not recommended for people with active liver or kidney disease. If you take L-carnitine as a supplement to improve fat metabolism and muscular performance, it is recommended that you skip using it one week each month. If you take it in large quantities (5 g a day by an adult), you may experience diarrhea.

Additional research into the long-term safety of L-carnitine as a supplement is needed.

Possible Interactions

Blood levels of carnitine may be reduced by the anticonvulsant medication valproic acid and may cause carnitine deficiency. Supplementation with carnitine may prevent carnitine deficiency and may also alleviate the side effects of valproic acid.

Supporting Research

Brass EP, Hiatt WR. The role of carnitine and carnitine supplementation during exercise in man and in individuals with special needs. J Am Coll Nutr. 1998;17:207-215.

Chung S, Cho J, Hyun T, et al. Alterations in the carnitine metabolism in epileptic children treated with valproic acid. J Korean Med Soc. 1997;12:553-558.

De Vivo DC, Bohan TP, Coulter DL, et al. L-Carnitine supplementation in childhood epilepsy: current perspectives. Epilepsia. 1998;39:1216-1225.

Elisaf M, Bairaaktari E, Katopodis K, et al. Effect of L-Carnitine supplementation on lipid parameters in hemodialysis patients. Am J Nephrol. 1998;18:416-421.

Haas EM. Staying Healthy with Nutrition. Berkley, California: Celestial Arts Publishing; 1992:65-79.

Kelly GS. L-Carnitine: therapeutic applications of a conditionally-essential amino acid. Alt Med Rev. 1998;3:345-60.

Murray MT. Encyclopedia of Nutritional Supplements. Rocklin, Calif: Prima Publishing; 1996:283-295.

Murray MT, Pizzorno JE. Encyclopedia of Natural Medicine. 2nd ed. Rocklin, Calif: Prima Publishing; 1996:206, 216, 246-247, 424, 505-506, 584.

Newstrom H: Nutrients Catalog. Jefferson, NC: McFarland & Co., Inc.; 1993:103-105.

Plioplys AV, Plioplys S. Amantadine and L-carnitine treatment of chronic fatigue syndrome. Neuropsychobiology. 1997;35(1):16-23.

Shils ME, Olson JA, Shike M, Ross AC. Modern Nutrition in Health and Disease. 9th ed. Baltimore, Md: Williams & Wilkins; 1999: 90-92; 1377-1378.

Van Wouwe JP. Carnitine deficiency during valproic acid treatment. Int J Vit Nutr Res. 1995;65:211-214.

Werbach MR. Nutritional Influences on Illness. 2nd ed. Tarzana, Calif: Third Line Press; 1993:13-22, 655-671.

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