Although listed under the classification of an amino acid, glutathione is actually a tripeptide compound. The human body produces glutathione from the synthesis of three key amino acids - cysteine, glycine, and glutamic acid. ‘Glutathione’ is, in fact, a term referring to the reduced and dimeric forms of the tripeptide L-gamma-glutamyl-L-cysteinylglycine. Biochemists often refer to this reduced form as glutathione, and the dimer form as glutathione disulfide.
 

Glutathione exists as a fundamental compound in all aerobic organisms. In human physiology, glutathione functions as an antioxidant, detoxifier, metabolic enhancer, and component in fatty-acid synthesis. It also acts as a redox buffer, reconstituting antioxidants Vitamin C and E post oxidation. Glutathione is found in varying concentrations in all tissues, with the highest amounts located in the liver, spleen, pancreas, kidneys, and lenses of the eye.

Supplemental glutathione is only available in one active form, GSH. Other oral formulas are often questioned and criticized due to their ineffectiveness and instability when administered. It is often suggested that the increase of glutathione levels within the body directly coincides with the increase of glutathione precursors (raw materials which make glutathione). The N-acetyl form of cysteine (NAC) may conceivably be the most effective amino at increasing overall glutathione levels. [1] This nonessential nutrient (i.e. NAC) may also be derived from the additional supplementation of L-cysteine, L-glutamic acid, and L-glycine.