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.
Phenylalanine comes in several forms as a supplement:
L-phenylalanine is an essential amino acid. It's also found in protein in the foods we eat.
DL-phenylalanine, which contains both the D- and L-forms
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.
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.