N-Acetyl CysteineAmino acid precursor of glutathione, a powerful antioxidant Designs for Health offers N acetyl cysteine in a 900 mg capsule. N acetyl cysteine (NAC) is an important amino acid precursor of glutathione (GSH), one of the most powerful intracellular antioxidants in the body, which promotes the optimization of phase II of hepatic biotransformation (detoxification of the liver). NAC is the most stable form as a nutritional supplement of the amino acid L