NAC Timing Secrets: What is the best time to take NAC? 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: 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 Wait until you see what N acetyl cysteine (NAC) can do! Free radical protection* Maintains cellular health* A sulfur containing amino acid* Promotes production of glutathione* *These statements have not