Carnitine, in the form of L-carnitine, is a trimethylated amino acid that is
essential for the transformation of fatty acids into energy for muscular
activity. This transformation occurs in the mitochondria, producing coenzyme
A typical daily diet contains from 5 to 100 mg of carnitine. Most of the
carnitine in the human body is synthesized from the essential amino acid lysine
with the aid of methionine, another essential amino acid. The normal rate of
carnitine synthesis in humans is approximately 1.2 micromoles per kg body
Deficiency or depletion can occur secondary to various genetic and acquired
disorders and conditions that impair the efficiency of carnitine reabsorption or
increase the rate of excretion. Primary carnitine deficiency usually results
from genetic disorders in carnitine transport. Such deficiency usually presents
before age 5, and may be manifested by progressive cardiomyopathy, skeletal
muscle weakness, and episodes of fasting hypoglycemia. Dietary deficiencies are
rare, but occur most often in vegetarians, preterm infants, and during pregnancy
or lactation. However, as vegetarians often have low-fat diets, they often have
less risk of cardiovascular disease. Deficiencies may increase symptoms of
fatigue, angina, muscle weakness, or confusion.
For supplementation, the L-carnitine form, alone or bound either to acetic or
propionic acid, should be used. The D-carnitine form has produced undesirable
side effects and should not be used.
The primary dietary sources of L-carnitine are red meats. Secondary sources
include other animal-based food products such as fish, poultry, and milk
products. Lesser sources include tempeh (fermented soybeans), wheat, and
Carnitine is a zwitterionic quaternary amine with a molecular weight of 161.2
g/mol. The chemical name is beta-hydroxy-gamma-N,N,N-trimethylaminobutyric acid.
The body produces carnitine, primarily in the liver and kidneys, from lysine
with the help of vitamin C, pyridoxine, niacin, iron, and methionine. It is
stored primarily in the skeletal muscles and heart; it is also concentrated in
sperm and in the brain.
- Carnitine is available in several commercial preparations. The
L-carnitine form is most often recommended. It is available alone, or linked
with acetic acid or propionic acid.
- L-carnitine (LC) is the most widely available form, is least
expensive, and has been studied the most.
- L-acetylcarnitine (LAC) appears to be best for Alzheimer's disease and
- L-propionylcarnitine (LPC) may be best for angina and other cardiac
- Prevention of cardiovascular diseases: Carnitine facilitates oxidation
of glucose in working hearts by relieving inhibition of pyruvate dehydrogenase
by fatty acids.
- Congestive heart failure: L-propionylcarnitine (LPC) improves cardiac
- Early administration in patients with heart attacks has been found to
reduce heart damage.
- Reduction of pain of angina; may be an effective alternative to other
- One study has suggested that carnitine may be as beneficial as
quinidine in treating cardiac arrhythmia without depressing blood pressure.
- Reduction of blood triglycerides and cholesterol levels; increase in
- Alcoholism: May inhibit alcohol-induced fatty liver.
- Alzheimer's disease: L-acetylcarnitine (LAC) may delay progression of
the disease; also may be beneficial in treating senile depression and
age-related memory defect.
- Anorexia: Supplementation may be beneficial.
- Diabetes mellitus: Supplementation with carnitine assists in glucose
tolerance, stimulating immune defenses, and reducing the risk and severity of
some secondary complications.
- Down's syndrome: Treatment with L-acetylcarnitine (LAC) improves
visual memory and attention.
- Epilepsy (childhood): intravenous L-carnitine is indicated for
valproate (VPA)-induced hepatotoxicity and overdose. Oral supplementation is
suggested for VPA-associated hyperammonemia or renal-associated symptoms in
infants and young children, and for individuals with epilepsy using the
ketogenic diet who have hypocarnitinemia.
- Chronic fatigue syndrome: L-carnitine supplementation is beneficial in
the treatment of CFS.
- Hemodialysis: Relatively low doses of L-carnitine supplementation may
be beneficial for hypertriglyceridemic hemodialysis patients.
- Immune system response: Even at low concentration levels, L-carnitine
has been shown to neutralize lipid-induced immunosuppression; it has also been
shown to increase the proliferative response of human lymphocytes following
- Infertility, male: In one study, supplementation was shown to increase
sperm count and motility in 80% of men with abnormal sperm mobility.
- Weight loss: In addition to aiding in weight loss, or perhaps as a
consequence of weight loss, carnitine has been linked to improvement of exercise
capacities and endurance.
|Dosage Ranges and Duration of
- To improve fat metabolism and muscular performance, supplementation
levels of 1,000 to 2,000 mg per day, usually divided into two doses
- For treatment of ischemic heart disease and hyperlipid states
(specifically, Type IV hyperlipidemia): doses of 600 to 1,200 mg tid or 750 mg
- For treatment of alcoholic fatty liver: 300 mg tid
- For treatment of male infertility: 300 to 1,000 mg tid
Supplements in large quantities (approximately 5 g/day by an adult) may cause
diarrhea or fish odor syndrome.
- Not recommended for individuals with active liver or kidney disease.
- Supplementation for improvement of fat metabolism and muscular
performance should probably be stopped one week each month.
- Additional research into long-term safety as a supplement is needed.
In an in vitro study with human muscle tissue, the addition of L-carnitine (5
mM) to muscle cultures pretreated with AZT (0.0027 to 135 mcg/mL) preserved the
integrity and volume of mitochondria (Semino-Mora et al. 1994). Coadministration
of L-carnitine to AIDS patients on AZT therapy may prevent the development of
myotoxicity typically associated with this
In one study, isolated cardiac myocytes and rat mitochondria perfused with
doxorubicin (5 mM) treatment with L-carnitine reversed the cardiotoxic affects
associated with the drug without affecting therapeutic effects (Sayed-Ahmed et
al. 1999). In another study with mice, carnitine significantly decreased cardiac
toxicity at both acute high and chronic intermittent low doses (Alberts et al.
1978). The cardiotoxic effects of doxorubicin were not observed in children
treated with a combination of doxorubicin (30 to 60 mg/kg) and carnitine (1 to 2
g) (Chavez et al. 1997).
Alberts DS, Peng YM, Moon TE, Bressler R. Carnitine prevention of adriamycin
toxicity in mice. Biomed. 1978;29(8):265-268.
Brass EP, Hiatt WR. The role of carnitine and carnitine supplementation
during exercise in man and in individuals with special needs. J Am Coll
Chavez GA, Hernandez IM, Ollarve CF, Natera YM. Myocardial protection by
L-carnitine in children treated with adriamycin. Rev Lat Cardiol.
De Vivo DC, Bohan TP, Coulter DL, et al. L-Carnitine supplementation in
childhood epilepsy: current perspectives. Epilepsia.
Elisaf M, Bairaaktari E, Katopodis K, et al. Effect of L-Carnitine
supplementation on lipid parameters in hemodialysis patients. Am J
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Kelly GS. L-Carnitine: therapeutic applications of a conditionally-essential
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Murray MT. Encyclopedia of Nutritional Supplements. Rocklin, Calif:
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Murray MT, Pizzorno JE. Encyclopedia of Natural Medicine. 2nd ed.
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Newstrom H: Nutrients Catalog. Jefferson, NC: McFarland & Co.,
Plioplys AV, Plioplys S. Amantadine and L-carnitine treatment of chronic
fatigue syndrome. Neuropsychobiology. 1997;35(1):16-23.
Sayed-Ahmed MM, Shaarawy S, Shouman SA, Osman AM. Reversal of
doxorubicin-induced cardiac metabolic damage by L-carnitine. Pharmacol
Semino-Mora MC, Leon-Monzon ME, Dalakas MC. Effect of L-carnitine on the
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