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 N A C GLUTATHIONE PRECURSOR 500MG NAC is a great supplement. It's awesome stuff to support healthy lungs. NAC is a known mucolytic. That is a fancy term meaning breaking up mucus. Now, research does show that NAC Glutathione, NAC & Vitamin C 30 Veg caps NutrinLife NAC L Glutathione Complex Vegecapsule 2x30's [Improved Form AA Pharmacy