What is L-Carnitine?


Is L-Carnitine really as good as it sounds?

L-Carnitine is often referred to as an “amino acid like” substance. The body synthesizes Carnitine from the amino acids L-Lysine and L-methionine. High levels of carnitine can be found in animal meats, especially red meats, from cows, lamb and sheep. Carnitine has many functions in the human body, but is best known for its ability to shuttle long chain fatty acids across the membrane of cells so they can be burned (oxidized) for energy by the mitochondria.

l-carnitine supplementation

l-carnitine supplementation

Mitochondria are often referred to as the “power house” of cells where energy is produced. The actual process of how carnitine shuttles fatty acids to the mitochondria is fairly complex and detailed. Suffice to say, it involves several enzymes and steps before the fats you want to burn end up being utilized by the mitochondria. So, the carnitine shuttle system is essential for the body to be able to burn fats as energy and this is why companies sell carnitine as a “fat burner.”

Studies that have focused on weight loss in people using carnitine as a supplement are few and conflicting. There are far more studies that look at carnitine as a sports and energy enhancing supplement, with some studies suggesting carnitine may help endurance athletes.

In animals, some studies have found increases in the use of fat for energy with high dose carnitine supplementation, but human studies are mixed, with some showing effects on endurance while others find no effect.

The difference may be dose and or the nutritional status of the athletes being tested. Doses used are generally high, in the multi gram range (2000mg-5000mg) and higher.

Carnitine does appear to have real health uses and is even listed in the Physicians D0esk Reference (a.k.a. the PDR) for certain pathologies involving the heart. Many alternative doctors swear by it for that use. Carnitine may also help reduce cholesterol and increase HDL cholesterol, the “good” cholesterol.

Although it may very well have potential health benefits in certain people, carnitine’s performance improving and “fat burning” abilities are questionable until more conclusive research is carried out. People who wish to try carnitine will need to use at least 500 milligrams (mg) or more several times daily, with some studies using 5g to 6g (5000mg-6000mg) or more, daily.

Carnitine is a very safe supplement with no known toxic effects, which is often found as an ingredient in weight loss formulas. People would be wise however to check the dose in such formulas as higher doses are clearly needed for any effect.

For general health and other uses, carnitine gets a thumb’s up, but for building muscle it gets a thumb’s down. For possibly improving endurance, it may be worth a try, albeit an expensive try if you follow the doses used in the studies.

Animal products like meat, fish, poultry, and milk are the best sources. In general, the redder the meat, the higher its carnitine content.

Foods Containing L Carnitine

Foods Containing L Carnitine

What foods provide carnitine?

Table 1: Selected food sources of carnitine
Food Milligrams (mg)
Beef steak, cooked, 4 ounces 56–162
Ground beef, cooked, 4 ounces 87–99
Milk, whole, 1 cup 8
Codfish, cooked, 4 ounces 4–7
Chicken breast, cooked, 4 ounces 3–5
Ice cream, ½ cup 3
Cheese, cheddar, 2 ounces 2
Whole–wheat bread, 2 slices 0.2
Asparagus, cooked, ½ cup 0.1

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