N-Acetyl L-Cysteine or "NAC" is derived from simple amino acid cysteine and is of great medicinal value. N-acetyl-cysteine has the ability to neutralize cell and DNA damaging free radicals and therefore plays an important role in slowing down the process of aging. As such, it protects us from a wide range of modern toxins including paraquat (a toxic herbicide), acrolein (present in cigarette smoke and auto exhaust), halothane (an anesthetic), adriamycin (both anticancer drugs) and hazardous side effects of cyclophosphamide. Apart from this toxin protection, it also facilitates in converting and synthesizing glutathione, an amino acid that is found in every cell. This amino acid comprises of glycine, L-glutamic acid, and L-cysteine, out of which glycine and L-glutamic acid are present in large quantities in our diets. Despite this, our bodies can produce glutathione only in limited quantities due to limited availability of cysteine. N-acetyl-cysteine supplements thus help the body increase production of glutathione.