glutathione
Meaning of glutathione: Its working end is a single sulfur atom, which is what lets the molecule absorb damage and then be restored for reuse.
Definition of glutathione
Glutathione is a small molecule built from three linked amino acids and manufactured inside nearly every cell of the body. It protects cells by neutralizing reactive compounds that would otherwise damage proteins, membranes and DNA, and it helps attach unwanted substances to a carrier so they can be cleared from the body.
How does it protect a cell?
Normal metabolism produces reactive forms of oxygen as a byproduct, and radiation, pollutants and inflammation produce more. These fragments react with whatever they meet, which is damaging when what they meet is a membrane or a strand of DNA. Glutathione contains a sulfur atom carrying a loosely held hydrogen, and it gives that hydrogen away readily, satisfying the reactive fragment before it reaches anything important. Two spent molecules then join together, and an enzyme splits them apart again using energy drawn from metabolism, so the same pool is recycled continuously. The ratio between the fresh and the spent forms is used in research as a measure of how much oxidative stress a tissue is under.
What else does it do?
A second role is disposal. A family of enzymes, the glutathione S-transferases, attach glutathione onto drugs, industrial chemicals and internal waste products, and that tag both neutralizes the substance and marks it for removal in bile or urine. This is the step that makes acetaminophen safe at ordinary amounts: a small reactive fraction is captured by glutathione and excreted, and liver injury follows only once that supply is exhausted. Glutathione also helps regulate proteins by attaching to them reversibly, and it keeps other antioxidants in their working form.
Do supplements raise the level inside cells?
| Route | What is known |
|---|---|
| Made inside the cell | Supplies effectively the whole working pool, built from three amino acids, with cysteine the one usually in shortest supply |
| Swallowed as a nutritional supplement | Largely broken into its component amino acids during digestion; whether it raises levels inside cells is unsettled |
| Cysteine precursors | Provide the limiting building block; one of them is the established treatment given after acetaminophen overdose |
| Injected preparations | Marketed for skin lightening without established benefit, and associated with reported harms and unregulated products |
Low levels are described in liver disease, in some metabolic and neurological conditions and in critical illness, though whether that is a cause or a consequence of the illness is usually unclear.
Also known as
Used in a sentence
Laboratory research measured glutathione levels within liver cells exposed to the experimental compound.
Good to know
Glutathione produced naturally within cells is distinct from glutathione taken as an oral supplement, since ingested glutathione is broken down during digestion and does not necessarily raise levels within cells in the same way.