N Acetyl L Cysteine (NAC) glutathione precursor Glutathione vs. NAC: Which Antioxidant Is Best for Your Liver? Life Extension 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 What Are NAD and NAC? MegaFood NAC vs Glutathione: Which Antioxidant Is Right for You? Momentous What's the Difference Between NAD and NAC?