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. Foods that increase amino acid intake are meat, beans, cheese and eggs.

L-Cysteine is an amino acid, bearing sulphur, which plays a role in metabolism as it assists the synthesis from fatty acids into energy. It is also involved in the synthesis of keratin, the protein in skin, hair and nails. It can be used to make glutathione.NAC 600 mg comes in a daily dose of 1 vegetable capsule, for easy absorption.