N Acetylcysteine (NAC): Impacts on Human Health N acetylcysteine supplementation increases exercise performance and reduces oxidative stress only in individuals with low levels of glutathione ScienceDirect The Importance of Glutathione in Health and Healing Dr. Todd Maderis 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