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 L Glutathione NAC Collagen Detoxification Whitening Antioxidant 120 Capsules The mechanism of action of N acetylcysteine (NAC): The emerging role of H2S and sulfane sulfur species ScienceDirect NAC Glutathione Antioxidant Support Praana Integrative & Functional Medicine, PLLC NAC Antioxidant & Detox Support Allergy Research Group