Glutathione — EU research guide.
Glutathione (GSH) is the most abundant endogenous antioxidant tripeptide in human cells, consisting of glutamate, cysteine and glycine. It is central to oxidative stress defence, detoxification and immune function.
What is Glutathione?
Glutathione exists in reduced (GSH) and oxidised (GSSG) forms. GSH is synthesised in cells from its constituent amino acids and acts as a cofactor for glutathione peroxidase (removing H₂O₂), glutathione S-transferase (detoxification) and thioredoxin reduction. Depletion is associated with aging, chronic disease and oxidative stress states. Injectable glutathione is used in clinical settings for specific indications.
What does the research show?
Oral bioavailability of glutathione is limited — it is largely degraded in the GI tract. IV or liposomal delivery achieves meaningful plasma elevation. Clinical research in Parkinson's disease, mitochondrial disorders and chemotherapy-related neuropathy has yielded mixed results. Skin brightening via melanin pathway modulation is actively studied, particularly in Asian dermatology literature. N-acetylcysteine (NAC) is often studied as a more bioavailable precursor.
EU legal status
Glutathione is a legal food supplement ingredient in the EU. Injectable research-grade glutathione is available for laboratory and clinical research. IV glutathione for skin brightening is used off-label in some contexts — regulatory status varies by member state.
Molecular information
Pharmacokinetics
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Frequently asked questions
What is Glutathione? ▾
Glutathione is a tripeptide (Glu-Cys-Gly) that exists in reduced (GSH) and oxidised (GSSG) forms. GSH acts as a cofactor for glutathione peroxidase, glutathione S-transferase and thioredoxin reduction, and its depletion is associated with aging and oxidative stress.
Why is oral glutathione considered poorly bioavailable? ▾
Oral glutathione is largely degraded in the GI tract, so IV or liposomal delivery is used to achieve meaningful plasma elevation.
What does the research show? ▾
Clinical research in Parkinson's disease, mitochondrial disorders and chemotherapy-related neuropathy has yielded mixed results, while skin brightening via melanin-pathway modulation is actively studied.
Is glutathione legal in the EU? ▾
Oral glutathione is a food supplement, while IV or injectable glutathione is handled as a research compound.
Is glutathione banned in sport? ▾
No. It is not prohibited by WADA.
What is the difference between GSH and GSSG? ▾
GSH is the reduced, active antioxidant form and GSSG is the oxidised form. The ratio between them reflects cellular oxidative status.