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L-Carnitine

Carnitine helps make energy in your body. Most carnitine comes from the liver and kidneys, but you also get some from food. People take carnitine supplements for athletic performance, heart disease, memory problems, and other issues.

Most supplements contain one type of carnitine called L-carnitine. It's the same type that's in food.

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Why do people take L-carnitine?

While carnitine is needed for good health, you probably have all that you need. People with genetic problems and some diseases -- as well as pre-term babies -- may have low levels. L-carnitine supplements may help them.

L-carnitine is a popular supplement for athletes. However, studies have not found that it helps improve sports performance or endurance.

L-carnitine supplements do seem to help with heart disease and other heart problems. Studies show it may help people with a history of heart attacks, along with standard treatment. It may also improve health in people with chest pain, heart failure, and peripheral artery disease.

L-carnitine supplements may help with thyroid problems, male infertility, memory and thinking problems in older people, chemotherapy side effects, and type 2 diabetes. We need more research to know for sure, though.

There's no standard dose of L-carnitine. For heart health, doses range from 1 g to 6 g a day. Ask your health care provider for advice.

Can you get carnitine naturally from foods?

Carnitine is in many animal products. Red meat has the highest levels. A 4-ounce beef steak has an estimated 56 mg to 162 mg of carnitine. Carnitine is also found in smaller amounts in chicken, milk and dairy products, fish, beans, and avocado. Vegans tend to get less carnitine from foods, but their bodies usually produce enough anyway.

What are the risks?

Tell your doctor about any supplements you’re taking, even if they’re natural. That way, your doctor can check on any potential side effects or interactions with medications.

  • Side effects. L-carnitine supplements can sometimes cause nausea, diarrhea, cramps, or vomiting. High doses can make you smell "fishy."
  • Risks. If you have Alzheimer's disease, a seizure disorder, or kidney disease, talk to a doctor before using L-carnitine supplements. Given the lack of evidence about its safety, doctors don't recommend L-carnitine for pregnant women.
  • Interactions. If you take any medicines regularly, you must talk to your doctor before you start using L-carnitine supplements. They could interact with drugs like antibiotics for infections.

Supplements are not regulated by the FDA.

WebMD Medical Reference

Reviewed by David Kiefer, MD on January 16, 2013

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