1. What is it and where does it come from?

L-carnitine is very similar to the nonessential amino acid carnitine. It performs some of the same functions, such as helping metabolize food into energy.

L-carnitine is synthesized in the body from the amino acids lysine and methionine. L-Carnitine is available as a high quality supplement from Bodybuilding.com, as well as from natural and synthetic sources. It is also found in avocados, dairy products, and red meats (especially lamb and beef).

2. What does it do and what scientific studies
give evidence to support this?

L-carnitine transfers long-chain fatty acids, such as triglycerides into mitochondria (a cell's energy powerhouse), where they may be oxidized to produce energy. L-carnitine is a very popular supplement that promotes growth and development. It is also used for fat-burning, increasing energy, and improving resistance to muscle fatigue. As a speculated muscle disease, liver disease, and kidney disease fighter, L-carnitine has also been shown to help build muscle and treat some forms of cardiovascular disease. It is also great in dieting, as it reduces feelings of hunger and weakness.

Studies have been conducted on L-carnitine since as early as 1937. They show that the body's cardiovascular system can greatly benefit from its intake. The FDA has approved L-carnitine under the name Carnitor for use in treating heart disease and low energy levels. Also, there are a variety of published studies that show L-carnitine is useful in increasing the heart's output and improving it's functioning, as well as stimulating the heart's energy supply and improving cardiac performance. Moreover, some experts have shown it increases endurance and helps regulating heart arrhythmia.

3. Who needs it and what are some symptoms of deficiency?

Anyone deficient in protein or amino acids in their diet could benefit from L-carnitine supplementation. Pre-mature infants, vegan vegetarians, children, and breast-feeding women are likely to be deficient, in addition to those on hemodialysis, and burn or injury victims.

Although deficiencies are rare, muscle fatigue, cramps, or pre-mature aging are all signs of possible deficiency. A person may also be L-carnitine deficient if their kidneys seem to not function properly after exercise. Other symptoms of possible deficiency are heart irregularities after a heart attack or angina.

4. How much should be taken? Are there any side effects?

Between two and four grams of L-carnitine should be taken one hour before exercise, for two weeks.

Taking L-carnitine is very safe, although the DL form of carnitine may be toxic and is not recommended.

NOTE: Acetyl-L-Carnitine products are different and are not reviewed on this page. Click here to check them out.