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 HealthKart HK Vitals Glutathione with Vitamin C & E, Biotin, Grape Seed Extract N Acetyl Cysteine (NAC Supplement) Benefits and Dosage Dr. Axe Schematic representation of vitamin E vitamin C glutathione antioxidant Download Scientific Diagram