Amino acids are the building blocks of protein and are needed in several internal functions of the body. They are classified as "essential" or "non-essential", with essential amino acids meaning they cannot be manufactured by the body and must be supplied in the diet to maintain good all-round health. Amino acids can be further used by the body to create hormones, enzymes, neurotransmitters, antibodies and nutrient carriers. A suboptimal intake of the essential amino acids increases the body's need for the non-essential amino acids either through diet or supplementation.

Carnitine is actually a dipeptide - an amino acid made up of two other essential amino acids; Methionine and Lysine. L-Carnitine is important for fat metabolism, especially in heart and muscle cells. It helps to transport long chain fatty acids into cell mitochondria where they can be burned up and used as fuel. Rich sources of carnitine are meat and dairy products and some dietary carnitine may be needed as the amount made by the body may not be enough.