What is glutathione and why must we protect patient access to it? Glutathione is nicknamed the master antioxidant because it is the most abundant, body produced (endogenous) antioxidant found in every cell, essential for neutralizing free radicals, recycling other antioxidants (like Vitamin C and E), Glutathione is the body's primary internal antioxidant, made using the amino acid cysteine, and it helps protect cells from oxidative stress. Beyond detoxification, research shows glutathione is involved in thyroid hormone metabolism, The Biological Functions of Glutathione Encyclopedia MDPI Figure 1 from The role of glutathione in photosynthetic organisms: emerging functions for glutaredoxins and glutathionylation. Semantic Scholar