Glutathione vs. NAC: Why You Should Take NAC for Better Absorption 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 Breathe Better, Detox Deeper: The Power of Glutathione + NAC Nebulizer Calibrate Hydration L Glutathione VS NAC: Differences, Similarities, and Uses N Acetyl Cysteine (NAC) + Glycine 800mg 60 Caps