N-Acetyl-L-Cysteine, or NAC, is a free-form amino acid required by the body to make glutathione. Glutathione is part of the body’s antioxidant defence system, recognized for supporting healthy aging. Taken by itself, glutathione is poorly absorbed, but NAC facilitates our body’s own production of it. It is an especially beneficial supplement for active people, the elderly, individuals exposed to pollution, and anyone else wanting to have healthy levels of glutathione, our master antioxidant.