As I mention in my book, N acetyl cysteine (NAC) is not found in food sources, but in the body, it converts into cysteine. NAC acts as a precursor to glutathione, a powerful NAC N Acetyl L Cysteine NAC vs. Glutathione and How They Work Invigor Medical Exploring the Evidence of N Acetyl Cysteine (NAC) for Mood Disorders Psychopharmacology Institute All About NAC (N acetylcysteine): What it is and what benefits it has Zenement N Acetylcysteine (NAC): Impacts on Human Health