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 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 Catabolism of extracellular glutathione supplies cysteine to support tumours Nature Isaac Harris 75 comments Life Extension Glutathione, Cysteine & C Powerful Antioxidants to Su Hebron Nutrition Natural Factors N Acetyl L Cysteine 500 mg 90s Fiddleheads Health and Nutrition NAC vs Glutathione: Differences, Similarities And Health Benefits