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 Amazon.com: 2 Pack NAC Supplement (N Acetyl Cysteine) 1,000mg Serving with Reduced Glutathione, 480 Capsules : Health & Household The Combined Antioxidant Effects of N Acetylcysteine, Vitamin D3, and Glutathione from the IntestinalNeuronal In Vitro Model NAC MegaFood NAC vs Glutathione: Comparing Antioxidant Powerhouses for Your Health IVDrips