N ACETYLCYSTEINE (NAC) Glutathione vs NAC: Key Differences, Benefits, and When to Use Each OrganiClinic Our Science Nacuity Pharmaceuticals 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 Glutathione: Master Antioxidant, Reducing Oxidative Stress, and Detoxification Glutathione, NAC & Vitamin C 30 Veg caps