N-acetyl cysteine (NAC) is 100% pure pharmaceutical grade amino acid powder, derived from the amino acid L-cysteine. This 'acetylated' form is known to be more stable than L-cysteine which may play an important role in the production of the free radical fighter, glutathione. Glutathione is one of the body's most important antioxidants. NAC (N-Acetylcysteine) is amazing for its powerful antioxidant properties, supporting liver health, and respiratory function, and helping to replenish glutathione—a key antioxidant in the body. A true health champion!