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 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.* L-carnitine also helps to build muscle.* 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. Those studies yielded positive results suggesting that the body’s cardiovascular system can greatly benefit from its intake.* There are a variety of published studies that suggest 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 supporting cardiac performance.*

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.
Although deficiencies are rare, muscle fatigue, cramps, or pre-mature aging are all signs of possible deficiency.

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.