N acetylcysteine (NAC): Health Benefits, Side Effects, Dosage, and More 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 Glutathione vs. NAC: Why You Should Take NAC for Better Absorption NAC) N ACETYLCYSTEINE VitaOne Amazon.com: DEAL SUPPLEMENT NAC Supplement (N Acetyl Cysteine) 1,000mg Per Serving with Reduced Glutathione, 240 Capsules Antioxidant Support for Immune Health, Lung, & Liver Function : Health & Household