Longevity & Cellular Aging
CAS
70-18-8
Molecular Weight
307
Da
The body's master antioxidant, a tripeptide found in nearly every cell. Strong biology, genuine human trials, but a long-running debate over whether supplemental glutathione is actually absorbed and raises tissue stores.
Oral · Liposomal · IV · Nasal · Topical
Intranasal Suitable
Uncertain
OTC Supplement
Glutathione discussion splits along a clean line: people treat it as the body's "master antioxidant" and a longevity staple, while more informed users push back hard on oral bioavailability, arguing that swallowed glutathione is largely digested and that NAC, liposomal forms, or IV are the only routes worth bothering with. The skin-brightening use case generates its own large, separate conversation, often citing IV protocols that sit well outside the supportive evidence and carry real safety concerns. The honest framing to hold: the biology of glutathione is not in question, but the supplement claims frequently outrun what absorption data can support.
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Glutathione (GSH) is a tripeptide. Its defining structural quirk is the gamma peptide bond, which makes it resistant to ordinary peptidases and is part of why it survives long enough to do its job intracellularly. It is the most abundant antioxidant the body produces on its own, central to neutralizing oxidative stress, recycling other antioxidants, and supporting detoxification in the liver.
Glutathione works mainly through its cysteine thiol (-SH) group, which donates electrons to neutralize reactive oxygen species and free radicals. In doing so it cycles between its reduced (GSH) and oxidized (GSSG) forms, and the GSH:GSSG ratio is a widely used marker of a cell's redox state. It also serves as a cofactor for glutathione peroxidase and glutathione-S-transferase enzymes, conjugates toxins for excretion, and helps regenerate vitamins C and E. The open question is pharmacokinetic, not biological: orally ingested glutathione is substantially broken down in the gut, so whether supplementation raises functional stores is route- and dose-dependent.
Studied and used for general antioxidant support, oxidative-stress reduction, liver health, immune function, and (especially in cosmetic markets) skin brightening. Intravenous and inhaled glutathione have been explored in Parkinson's disease and respiratory conditions. Most marketing outpaces the clinical evidence, which is strongest for raising body stores under specific formulations and weakest for hard clinical outcomes.
Generally well tolerated. Oral supplementation has a benign side-effect profile in trials; reported effects are mild and uncommon (bloating, cramping). Inhaled glutathione can trigger bronchospasm in some asthmatics. Long-term high-dose safety is not well characterized, and skin-lightening use via IV injection has drawn regulatory safety warnings in several countries due to unregulated compounding. Not a substitute for medical treatment of any condition.
Available as oral capsules and tablets, liposomal and sublingual formulations marketed for improved absorption, intravenous infusions (common in cosmetic and wellness clinics), nebulized/inhaled solutions used in research, and topical creams. Oral bioavailability of standard glutathione is the central limitation; liposomal and reduced-form products claim to address it with mixed supporting evidence. The precursor N-acetylcysteine (NAC) is often used as an alternative route to raise glutathione indirectly.
Oral glutathione is sold legally in the US and most markets as a dietary supplement and is not FDA approved as a drug to treat any disease. Intravenous glutathione is not FDA approved; its use in wellness and skin-lightening clinics relies on compounding, and the FDA and several national regulators have issued warnings about unapproved injectable glutathione products. It is not a controlled or scheduled substance.
https://pubmed.ncbi.nlm.nih.gov/24791752/
https://pubmed.ncbi.nlm.nih.gov/21875351/
https://pubmed.ncbi.nlm.nih.gov/35624890/
Carnosine, NMN
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