5 Reasons Why Glutathione is the Best 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, 7 THINGS YOU DIDN'T KNOW ABOUT GLUTATHIONE Glutathione: The Master Antioxidant Glutathione is often called the body's "master antioxidant" and for good reason. This powerful tripeptide (made from cysteine, glycine, and glutamate) is produced naturally in your cells, ,, ??