Glutathione: Biochemistry, Therapeutic Applications, Routes of Administration, and Dosing. A Structured Narrative Review of the Evidence

Glutathione is a small molecule that the body makes to protect its cells from damage and to help the liver clear toxins. Its levels fall with age and in many illnesses, which is one reason supplements and clinic injections are marketed so heavily. The evidence, however, is mixed. The clearest benefit comes not from glutathione itself but from its building blocks. N-acetylcysteine is a proven, life-saving antidote for paracetamol (acetaminophen) overdose, and a glycine-plus-N-acetylcysteine combination known as GlyNAC shows promise for healthy aging. Swallowed glutathione can slowly raise the body's stores over several months, whereas injections give a quick but short-lived spike and are not approved by the U.S. FDA, which has specifically warned against injectable glutathione sold for skin whitening. A good diet, regular exercise, and adequate sleep also help the body maintain its own glutathione.