L-carnitine is important for heart and brain function, muscle movement, and many other body processes. The body can convert L-carnitine to other chemicals called acetyl-L-carnitine and propionyl-L-carnitine. But it’s not clear whether the benefits of these other carnitines are the same.
L-carnitine is used to increase L-carnitine levels in people whose natural level of L-carnitine is too low. Some people also use L-carnitine for conditions of the heart and blood vessels, serious kidney disease, and many other conditions, but there is no good scientific evidence to support these uses.
How does it work ?
Uses & Effectiveness
Possibly Effective for
- Chest pain (angina). Taking L-carnitine by mouth or by IV seems to improve exercise tolerance in people with chest pain. Taking L-carnitine along with standard treatment also seems to reduce chest pain and improve exercise ability in people with cardiac syndrome X. People with this condition have chest pain but not blocked arteries. IV products can only be given by a healthcare provider.
- Heart failure and fluid build up in the body (congestive heart failure or CHF). Taking L-carnitine by mouth or by IV seems to improve symptoms and increase exercise ability in people with heart failure. IV products can only be given by a healthcare provider.
- High levels of cholesterol or other fats (lipids) in the blood (hyperlipidemia). Taking L-carnitine by mouth or by IV can improve cholesterol and triglyceride levels by a small amount. IV products can only be given by a healthcare provider.
- Kidney failure. The FDA has approved giving L-carnitine by IV, but not by mouth, for kidney failure. This can only be given by a healthcare provider.
- Conditions in a male that prevent a female partner from getting pregnant (male infertility). Taking L-carnitine by mouth, alone or together with acetyl-L-carnitine, increases sperm count and sperm movement in males with fertility problems. Some research shows that this increases the chance of pregnancy.
- Swelling (inflammation) of the heart (myocarditis). Some children who have had diphtheria can develop myocarditis. Taking DL-carnitine by mouth seems to reduce the risk of myocarditis and death in these children.
- A hormonal disorder that causes enlarged ovaries with cysts (polycystic ovary syndrome or PCOS). Taking L-carnitine by mouth can increase ovulation and the chance of getting pregnant in some people who don’t respond to the medication clomiphene. Also, taking L-carnitine might help with weight loss and improving blood sugar levels.
- Toxic side effects caused by the drug valproic acid. Toxicity caused by valproic acid seems to be linked with L-carnitine deficiency. Taking L-carnitine by mouth or by IV can prevent liver toxicity from valproic acid. IV products can only be given by a healthcare provider.
There is interest in using L-carnitine for a number of other purposes, but there isn’t enough reliable information to say whether it might be helpful.
Special Precautions and Warnings
Breast-feeding: Taking L-carnitine is possibly safe when taken by mouth while breast-feeding in the amounts recommended by a healthcare provider. Small amounts of L-carnitine have been given to infants in breast milk and formula with no reported side effects. The effects of large amounts are unknown.
Children: L-carnitine is possibly safe when used appropriately by mouth, short-term. It has been used safely by mouth for up to 6 months.
Underactive thyroid (hypothyroidism): Taking L-carnitine might make symptoms of hypothyroidism worse.
Seizures: L-carnitine seems to make seizures more likely in people who have had seizures before. If you have had a seizure, don’t take L-carnitine.