Posted 3/16/07CLICK TO PRINT

NAME: Carnitine (see also: Acetyl-L-Carnitine)

Also known as: L-carnitine and the intravenously-administered levocarnitine.

DESCRIPTION: Carnitine is an amino acid derivative (specifically, a quaternary ammonium compound) synthesized from lysine and methionine. It is found in nearly all cells of the body. Produced in the liver and kidneys, it is stored in the skeletal muscles, heart, brain, and sperm.

Carnitine is involved in transferring fatty acids across mitochondrial membranes.

Carnitine has been studied extensively, as it is a well-tolerated and safe therapeutic agent. Researchers prefer to use acetylcarnitine in their studies because it is better absorbed from the small intestine than L-carnitine and more efficiently crosses the blood-brain barrier.

FUNCTION: Cartinine plays a critical role in energy production. It helps move long-chain fatty acids into the mitochondria where they are converted into energy. It then works as an antioxidant, transporting the toxic compounds generated out of the mitochondira.

There has been a great deal of recent attention to carnitine because of researchers’ beliefs that mitochondrial toxicity can cause neuropathy, myopathy, bone marrow suppression (and resulting decreases in red and white blood cells and platelets), pancreatitis, fatty liver, lactic acidosis, and lipoatrophy (fat loss).

Research has already shown the usefulness of carnitine, usually in the form of acetylcarnitine, for reversal of several of these problems, including neuropathy, myopathy, and lactic acidosis.

In addition to its usefulness for preventing mitochondrial damage, there may be significant positive effects from carnitine supplementation via normalization of the levels of cytokines (proteins produced by white blood cells that act as chemical messengers between cells) such as tumor necrosis factor which can activate HIV, cause body-wide inflammation, suppress appetite, cause fatigue, and contribute to wasting.

Read more about mitochondrial stress on our Antioxidants and HIV Fact Sheet.

SOURCES: The richest dietary sources of carnitine are: red meats, with lesser amounts found in fish, poultry, and milk products. Small amounts are also found in wheat and avocados.

In general, the redder the meat, the higher its carnitine content: 4 oz. of cooked beef steak, for example, provides between 56 to 162 mg of carnitine, while the same amount of cooked chicken breast provides only 3 to 5 mg.

DOSAGE: Many PWHIV take a moderate dose of 500 mg to 750 mg per day elemental L-carnitine in an attempt to offset toxicity of nucleoside analogs, like AZT; some PWHIV are taking from 1–3 grams of elemental carnitine per day as a potential immune modulator.
DATA: Italian researchers have shown that carnitine is deficient in a high percentage of those in later HIV disease stages and it's likely that it's deficient in those in earlier stages to a lesser degree. In addition to the vulnerability to mitochondrial toxicity, carnitine deficiency can cause muscle wasting in both the heart and skeletal muscle tissue. Both heart dysfunction and wasting syndrome may result.

Italian researchers also showed that high doses of carnitine (6000 mg daily) improved immune function, increased energy, improved the heart muscle, helped reverse muscle wasting, and normalized levels of blood fats.

Some athletes take carnitine to improve performance, but there is no consistent evidence to prove its value in this regard.

Vitamin C (ascorbic acid) is essential to the synthesis of carnitine.

There is much ongoing research in non-HIV populations looking at the potential for L-carnitine to reverse angina and other aspects of heart disease. For this, it is thought that dosages of around 1000 mg daily may help reverse heart muscle wasting, with potential improvements in shortness of breath and energy problems via improvement in the heart muscle.

Acetylcarnitine has been licensed in several countries as a treatment for brain dysfunction in the elderly. It is thought to help increase circulation in the brain while improving neurotransmitter sensitivity, thus improving some forms of dementia. Whether it might help with HIV-associated brain problems via these mechanisms has not been shown, but since mitochondrial dysfunction may play a role in the creation of brain problems, its use to protect the mitochondria might help in this regard. 

CAUTIONS: High doses (5 or more grams per day) may cause diarrhea.

Use of carnitine may lower thyroid hormone levels (which produce energy and regulate body temperature). Symptoms of low thyroid hormone levels include: unexpected tiredness, feeling cold, dry skin, muscle weakness, forgetfulness and difficulty concentrating, and impaired hearing.

Lyn Patrick, ND (Doctor of Naturopathy), in Alternative Medicine Review, offers a comprehensive and well-documented overview of the use of several supplements in "Nutrients and HIV: Part Three – N-Acetylcysteine, Alpha-Lipoic Acid, L-Glutamine, and L-Carnitine"

National Institutes of Health / Office of Dietary Supplements' entry on carnitine is fairly robust, with a section devoted to its use in treating HIV/AIDS.

L-Carnitine 500 (Jarrow Formulas) Each bottle, 100 tablets. Each tablet, 500 mg carnitine from 750 mg carnitine tartrate (250 mg tartaric acid, 500 mg L-carnitine). This elemental, free-base, non-salt form of L-carnitine should not be confused with the commonly mislabeled tartrate, fumarate, or hydrochloride forms prevalent on the market today. This is the most concentrated form of L-carnitine available.

Acetylcarnitine Each bottle, 100 capsules. Each capsule, 500 mg of N-acetyl-L-carnitine.

PRODUCT NOTES: Keep refrigerated.

Over-the-counter L-carnitine can be expensive. Carnitor is a pharmaceutical (prescribed) form of L-carnitine which many medical insurance plans (including state-run medicaids) will pay for.

DISCLAIMER: These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.