"N-acetyl cysteine (NAC) is an amino-acid derivative (small protein) with over 40 years of scientific research to back it up. NAC’s powerful health benefits derive from its ability to restore intracellular levels of glutathione (GSH), which is the body’s most powerful antioxidant.
Glutathione is a very powerful antioxidant that helps the liver to protect you against toxicity, and it is most needed by those with liver disease. The stress of chronic liver disease depletes glutathione and this is why supplementing with one of its precursors, NAC helps to protect against ongoing liver damage.
NAC is a modified form of the sulfur-containing amino acid cysteine. NAC replenishes intracellular levels of glutathione (GSH), which restores your cells’ ability to fight damage from free radicals known as reactive oxygen species."