Glutathione: The Body's Master Antioxidant Explained 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, Glutathione: The Master Antioxidant Keeping Your Cells in Check Vitall L Glutathione vs. oxidized vs. Reduced Glutathione Glutathione The Master Antioxidant With Enormous Benefits Wellness By Rosh Integrative Wellness