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 Differential effects of N acetylcysteine on retinal degeneration in two mouse models of normal tension glaucoma Cell Death & Disease Glutathione Precursor, N Acetyl Cysteine, Improves Mismatch Negativity in Schizophrenia Patients Neuropsychopharmacology N acetylcysteine (NAC) ameliorates ethanol induced oxidative stress, neuroinflammation, and cognitive dysfunction in APP PS1 mouse model Translational Psychiatry