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 600mg 180 count Mark Hyman, MD N.A.C. N Acetylcysteine Vitazan Professional Amazon.com: Advanced Complex NAC Supplement (N Acetyl L Cysteine) 600mg with L Glutathione 500mg and Milk Thistle Extract Potent Antioxidant Immune Function Support Respiratory Health Promotes Liver Kidney Detox : Health & Household