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.
L-carnitine has been used in connection with the following conditions (refer to the individual health concern for complete information):
| Science Rating | Health Concerns |
|---|---|
 | Angina Congestive heart failure (propionyl-L-carnitine) Heart attack Intermittent claudication (propionyl-L-carnitine) |
 | Anemia (for thalassemia) Attention deficit–hyperactivity disorder Chronic fatigue syndrome Chronic obstructive pulmonary disease (COPD) Erectile dysfunction (in combination with acetyl-L-carnitine) High triglycerides Infertility (male) Intermittent claudication (L-carnitine) Multiple sclerosis Sprains and strains (for preventing exercise-related muscle injury) Type 1 diabetes Type 2 diabetes |
 | Athletic performance (for ultra-endurance only) Beta thalassemia major Cardiomyopathy (only for children with inherited cardiomyopathy) Chemotherapy-induced fatigue High cholesterol Liver cirrhosis Mitral valve prolapse Raynaud’s disease Weight loss |
| Reliable and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit. For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit. | |
Who is likely to be deficient?
Carnitine deficiencies are rare, even in strict vegetarians, because the body produces carnitine relatively easily.
Rare genetic diseases can cause a carnitine deficiency. Also, deficiencies are occasionally associated with other diseases, such as diabetes and cirrhosis.2 3 Among people with diabetes, carnitine deficiency is more likely to be found in persons experiencing complications of diabetes (such as retinopathy, hyperlipidemia, or neuropathy), suggesting that carnitine deficiency may play a role in the development of these complications.4 A carnitine deficiency can also result from oxygen deprivation which can occur in some heart conditions. In Italy, L-carnitine is prescribed for heart failure, heart arrhythmias, angina, and lack of oxygen to the heart.5
How much is usually taken?
Most people do not need carnitine supplements. For therapeutic use, typical amounts are 1–3 grams per day.
It remains unclear whether the propionyl-L-carnitine form of carnitine used in congestive heart failure research has greater benefits than the L-carnitine form, since limited research in both animals and humans with the more common L-carnitine has also shown very promising effects.6
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.
References
1. Giovannini M, Agostoni C, Salari PC. Is carnitine essential in children? J Int Med Res 1991;19:88-102.
2. Dipalma JR. Carnitine deficiency. Am Fam Physician 1988;38:243–51.
3. Kendler BS. Carnitine: an overview of its role in preventive medicine. Prev Med 1986;15:373–90.
4. Tamamogullari N, Silig Y, Icagasioglu S, Atalay A. Carnitine deficiency in diabetes mellitus complications. J Diabetes Complications 1999;13:251–3.
5. Del Favero A. Carnitine and gangliosides. Lancet 1988;2:337 [letter].
6. Kobayashi A, Masumura Y, Yamazaki N. L-carnitine treatment for congestive heart failure—experimental and clinical study. Jpn Circ J 1992;56:86–94.
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2006-09-07
