L-Carnitine

Medically Reviewed by Melinda Ratini, MS, DO on September 06, 2023
Written by R. Morgan Griffin
2 min read

Carnitine helps make energy in your body. Most carnitine comes from the liver and kidneys, but you also get some from food. 

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

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, muscle adaptations, or endurance.

L-carnitine may help certain patients survive heart attacks, have less heart rhythm disturbances, and less chest pain.  When added to regular medication therapy, carnitine may improve health in people with peripheral artery disease, but further research is needed.

It is thought that patients with cancer may become carnitine deficient, and so carnitine supplementation may be helpful to reduce chemotherapy side effects. We need more research to know for sure, though.

Researchers are still studying to find out if carnitine can improve memory and thinking problems in older people.

There's no standard dose of L-carnitine. Ask your healthcare provider for advice.

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.

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 many drugs such as antibiotics for infections.

Supplements are not regulated by the FDA in the rigorous way that food and medicine is. Manufacturers themselves are responsible to ensure the safety and labeling of their products.