N-acetyl-cysteine (NAC) is a stable form of the non-essential amino acid cysteine. Cysteine is a sulfur-containing amino acid that acts as a stabilizer for the formation of protein structures.* Although NAC possesses its own free radical scavenging activity, its primary function in the body is to supply cysteine necessary for glutathione synthesis and replenishment.* This unique formula also contains molybdenum, an essential trace element that functions as a cofactor in many biochemical reactions, and selenium, another trace mineral that supports glutathione production.*