What Is Carnitine and Should I Take It As a Supplement?

Red meat is high in carnitine.
Red meat is high in carnitine.. Sylvia Bissonnette / Getty Images

Question:  I've started lifting weights and I want to know if taking carnitine supplements will help me build muscles faster. Actually, I don't even know what carnitine is, or what it does in the body. Can you help me?

Answer: Carnitine is a substance found in the cells of your body, mostly in the skeletal muscles and heart muscles. It's necessary for energy production because it transports long-chain fatty acids into the mitochondria (powerhouses of the cells) to be burned for energy.

Then carnitine helps remove toxic wastes, so they don't build up in the mitochondria.

Dietary Sources of Carnitine

Carnitine is found in some of the foods you eat. Animal foods contain the most carnitine, especially beef, and lamb. Milk, fish, and chicken are all good sources, as well. Plant sources include wheat, asparagus, tempeh (a soy product), avocados, and peanut butter. A typical diet provides 60 to 180 milligrams of carnitine each day, although vegans get about 10 to 12 milligrams. Your body can conserve carnitine if you need it, but usually, excess carnitine is removed by the kidneys.

You don't need to worry about getting carnitine from your diet, even if you rarely eat meat because your body regularly makes carnitine in your liver and kidneys. Deficiency can occur, either from a genetic disorder that reduces the body's ability to produce or transport carnitine, as a side effect of certain medications or as the result of some heart conditions.

Carnitine Supplements

Carnitine is commercially available as a dietary supplement. Common forms include L-carnitine, acetyl-L-carnitine, and propionyl-L-carnitine. Don't use any D- forms because they can interact with your natural carnitine stores.

Because carnitine is essential for energy production, athletes often take carnitine supplements hoping to boost physical performance.

Carnitine supplements are also included in some weight loss aid. They're also touted as anti-aging supplements and as a way to improve memory. 

That all sounds really good, right? But, as usual, when something seems to good to be true, it probably isn't. Scientific evidence doesn't indicate any benefit of carnitine supplementation in any of those situations. 

Carnitine supplements aren't completely worthless, however. There are some situations when they're beneficial. Research supports the potential for carnitine as a treatment for claudication, which is a condition where the leg muscles don't get enough oxygen due to lack of blood flow. It may also help reduce the risk of heart failure in people who've already had heart attacks. Supplementation may increase sperm count in men who have low carnitine levels, and might also reduce some of the symptoms of hyperthyroid (overactive thyroid) disease.

Small studies also suggest carnitine may be beneficial for certain nerve problems, including diabetic neuropathy.

More research is needed in these areas and using carnitine supplements for these situations requires medical supervision, so speak to your health care provider before taking them.

Carnitine supplements can have unwanted side effects. They can cause nausea, increased appetite, a fish-like body odor, and rashes when taken in large doses (more than five grams per day). They can also interact with certain medications. 

Please speak to your health care provider before taking carnitine supplements.


National Institutes of Health, Office of Dietary Supplements. "Dietary Supplement Fact Sheet: Carnitine." Accessed April 11, 2016. http://ods.od.nih.gov/factsheets/Carnitine-HealthProfessional/.

University of Maryland Medical Center. "Carnitine (L-Carnitine)." Accessed April 11, 2016. http://www.umm.edu/altmed/articles/carnitine-l-000291.htm.

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