TMP Blog: All About Glutathione 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 is often called the body's master antioxidant, but what does that actually mean? Naturally produced in the body, it plays an important role in supporting cellular processes linked to protection against Dietary (Phyto)Nutrients for Glutathione Support Encyclopedia MDPI