The mechanism of action of N acetylcysteine (NAC): The emerging role of H2S and sulfane sulfur species ScienceDirect Amazon.com: NutraBio N Acetyl Cysteine Supplement (NAC) 90 Capsules, 600mg Each Powerful Anti Oxidant Immune Support Boost Glutathione : Everything Else 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 NAC for Thyroid Health Dr. Izabella Wentz, Pharm D N Acetyl Cysteine Functions as a Fast Acting Antioxidant by Triggering Intracellular H2S and Sulfane Sulfur Production: Cell Chemical Biology