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 vs Glutathione: Differences, Similarities And Health Benefits NAC Skin Care Benefits of NAC NAC (N acetyl cysteine) is a powerful compound that plays an important role in supporting the body's natural detoxification and antioxidant systems. One of its key functions is helping the body produce glutathione,