Glutathione for the skin Paula's Choice Enzymatic and Non enzymatic defense against ROS 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, Frontiers Glutathione: A Samsonian life sustaining small molecule that protects against oxidative stress, ageing and damaging inflammation Glutathione: Master Antioxidant, Reducing Oxidative Stress, and Detoxification