L-Carnitine is not an amino acid in the technical sense, because it does not function as a neurotransmitter or in protein synthesis, but it closely resembles an amino acid and is usually referred to as one. It is synthesized within the body from ingested lysine and methionine molecules. Lysine has been shown to help prevent atherosclerosis, a hardening of the walls of arteries caused by deposits of fats. It also may be capable of loosening and preventing such deposits, thereby keeping artery walls flexible and maintain a normal blood flow.1 Methionine helps lower cholesterol, reduces fatty liver deposits, and helps protects the kidneys from damaging substances.

Fat Burning: Once synthesized by the body into L-Carnitine, it aids in the metabolization and oxidization of long chain fatty acids in the bloodstream that bind themselves to cellular tissues. L-Carnitine transports these broken down fat particles to the mitochondria (fat burning) (See fig. 1) area of the cell where it can be converted into energy instead of being stored. Therefore, optimum levels have been shown to help improve energy levels in athletes and fatigue sufferers. Organs that derive most of their functional energy from fats have been found to have the highest concentrations of Carnitine. These include the heart, brain, liver, and the kidneys.

Heart Disease: By reducing these fats in the circulatory system and preventing them from collecting in the arterial walls, there is less of a chance for the development of heart disease, stroke, or other disorders that many times prove fatal.

L-Carnitine is also very beneficial for individuals already suffering from congestive heart failure, and it may even help to extend the lives of heart attack sufferers. The fumaric acid (shown to help extract energy from food) which is bound to the l-carnitine has been shown to help strengthen the heart muscle helps improve performance in doctor prescribed exercise regiments.

Liver and Kidney Function: It has been suggested that alcohol consumption impedes the functionality of existing carnitine. This can lead to excess buildup of fatty tissue in the liver and lead to cirrhosis and other maladies. Sufficient carnitine production is also vital to proper kidney function. The kidneys are vital for cleansing and detoxifying our entire system. Those going through regular dialysis have been found to have serious deficiencies of carnitine, which can cause further health deterioration.

Alzheimer's and Dementia: Although many studies are either inconclusive or conflicting, it has been suggested that optimal stores of carnitine may help delay the progression of Alzheimer's disease and reduce the severity of clinical depression that can be a factor in the onset of forms of dementia.

Proper levels may also be a factor in maintaining mental faculties in older people.

1. referenced from lysine.net
2. referenced from healthandage.com