A tripeptide made from three amino acids — glutamate, cysteine, and glycine — and the most abundant antioxidant inside human cells. Where most peptides on this site act as signals, glutathione is studied mainly as a defense system.
Glutathione (GSH) is a small tripeptide — glutamate, cysteine, and glycine — that nearly every cell in the body makes for itself. Unlike most of the peptides covered elsewhere on this site, it isn't studied as a signaling messenger that tells other cells what to do. It's studied as the cell's own first line of defense against oxidative damage.
Glutathione's job centers on keeping a cell's internal chemistry in balance — neutralizing harmful molecules before they can damage DNA, proteins, or the cell membrane itself.
Glutathione can donate electrons directly to neutralize free radicals and reactive oxygen species — the unstable molecules behind oxidative stress — before they damage cellular components.
GSH cycles between its reduced form (GSH) and oxidized form (GSSG) through glutathione peroxidase and glutathione reductase, acting as a buffer that keeps a cell's overall redox balance in check.
Beyond acting directly, glutathione is a required cofactor for several antioxidant and detox enzyme families — glutathione peroxidases, glutathione S-transferases, and glyoxalases among them.
Through glutathione S-transferases, GSH conjugates with toxins and other foreign compounds, making them more water-soluble so the body can clear them through urine or bile — a core part of the liver's phase II detoxification process.
Oral glutathione has limited bioavailability — much of it is broken down during digestion — which is why research and clinical use more often involve IV administration, or precursor compounds like N-acetylcysteine (NAC) instead.
Peptide Curious provides educational and editorial content only. It is not medical advice and is not a substitute for a qualified healthcare professional. Glutathione is discussed here as a research compound; content may describe emerging research not approved for clinical use.