T. J. Clark Liquid l-Carnitine: 

What is L-Carnitine?

L-carnitine is not an amino acid in the strict sense (it is not used as a neurotransmitter or in protein synthesis), however it bears many resemblances to amino acids and is usually grouped under this heading.
Carnitine (the "L" refers to its chemical polarity) is used by the body to transport long chain fatty acids to the mitochondria in your cells, where it is burned for energy. Since this fat burning is such a major source of muscular energy, deficiencies in carnitine are manifested as low energy levels and muscular weakness. They can also appear as mental confusion or cloudiness, angina (heart pain) and weight gain. 

Sources of Carnitine

Carnitine can be manufactured in the body provided the requisite vitamins and minerals are also present.
These vitamins and minerals are B1, B6, C, and iron. The amino acids lysine and methionine are also needed for carnitine synthesis. Carnitine is also present in meats and other animal foods, so if you are a vegetarian or vegan you may want to consider supplementing with carnitine. This would be especially important if you are an athlete, since you are using lots of carnitine during periods of exertion1,2. 

Carnitine Deficiency

We know already that carnitine deficiency, by denying the mitochondria the needed fatty acids, decreases energy output, but let's look at the other side of this energy equation. If you aren't burning fat, you must be storing it. This obviously leads to a variety of health problems, namely fatty build-ups. Carnitine supplementation can help prevent fatty build-ups in the heart and liver (especially likely if you are a regular consumer of alcoholic beverages). Putting it all together, carnitine emerges as a great supplement: it increases energy, burns fat (making it excellent addition to a weightloss program), and improves heart and liver health all at the same time!