Carnitine is found in large quantities in red meat, fish, chicken and milk, while vegetables and grains contain small amounts of this nutrient.
Carnitine is a vitamin-like nutrient (it is sometimes known as vitamin BT) and is essential for energy production and fat metabolism. Carnitine is not technically an amino acid, but because of the structural similarities it is normally classed as one. It is available as D-carnitine, L-carnitine, DL-carnitine as well as acetyl-l-carnitine, but with L-carnitine being the most popular type. L-Carnitine is synthesized from the essential amino acids lysine and methionine (enough vitamin B1, thiamine, and B6, pyridoxine, must be available for this to take place).
Primarily, carnitine deficiency occurs because of a genetic defect preventing carnitine transport and this may result in confusion, heart pains, muscular weakness, and obesity.
Carnitine's major metabolic role is associated with the transport of long chain fatty acids across the mitochondrial membranes (as well as for the removal of short-chain organic acids from the mitochondria), therefore stimulating the oxidation of these substrates for metabolic energy. It helps to prevent fatty build-up in areas such as the heart and liver, and may reduce the risk of poor fat metabolism in those with diabetes, as well as the risk of heart problems. Carnitine has also been shown to improve the antioxidant effect of vitamins C and E.
Esters of carnitine are thought to have pharmacological value, by virtue of their antioxidant properties and ability to deliver readily oxidizable carbon units to mitochondria, in chronic disorders such as Alzheimer's disease and myocardial dysfunction in angina.
Acetyl-l-carnitine is of great interest because it has been shown to counteract several physiological and pathological modifications typical of the brain-ageing processes. In particular, it has been demonstrated that it can counteract the age-dependent reduction of several receptors in the central nervous system of animals, such as the Nerve Growth Factor (NGF) receptors and neurotransmitters, thereby enhancing the efficiency of synaptic transmission, which is considerably slowed down by ageing and appears to reverse age-associated deficits in cellular function, in part by increasing cellular ATP production.