Value Size Pharmaceutical Grade Glutathione Intracellular Antioxidant Vegan Gluten Free Dietary Supplement Suitable for Vegetarians/Vegans Non GMO - Certified by NSF Glutathione is the most abundant intracellular thiol (i.e., a compound containing a sulfhydryl [SH] group) and low molecular weight tripeptide found in living cells. Thiols such as glutathione, alpha lipoic acid and N-acetyl-L-cysteine (NAC) are powerful sulfur-bearing antioxidants. The antioxidant functions of Glutathione Reduced include recycling vitamins E and C and serving as a critical free radical scavenger to support antioxidation in all types of tissues.