L-Glutathione

CAS Number	70-18-8 (reduced form, GSH; verified against PubChem CID 124886)
Molecular Formula / MW	C10H17N3O6S / 307.32 g/mol
Chemical Class	Tripeptide — γ-glutamyl-cysteinyl-glycine. Note the unusual γ-peptide bond
Source	Endogenously synthesised in nearly all cells; commercial material produced by fermentation
Forms	Reduced (GSH), oxidized (GSSG), and liposomal/micellar delivery systems
Typical Standardisation	GSH by HPLC, typically ≥98%. Reduced and oxidized forms are distinct products
Claim Strength (Overview)	Moderate — a 6-month RCT resolved much of the oral bioavailability controversy, but results across trials remain inconsistent
Buy from Herbuno	L-Glutathione (Reduced) Powder → Liposomal L-Glutathione Powder →

Name origin: Glutathione is named for its glutamate and thiol (sulfur) components. Structurally it is a tripeptide of glutamate, cysteine, and glycine — but with a chemical quirk of real consequence: the glutamate is joined through its side-chain carboxyl (a γ-peptide bond) rather than the usual α-linkage. This unusual bond is what makes glutathione resistant to most peptidases and gives it its intracellular stability. The reactive cysteine thiol is the business end of the molecule. Traditional use: None, and none should be implied. Glutathione is an endogenous metabolite, first described in the late 19th century and characterised structurally in the 1920s. Every therapeutic use of it is a product of 20th-century biochemistry. It is frequently called the "master antioxidant" — a marketing phrase rather than a technical one, though not an unreasonable description of its role as the principal intracellular redox buffer. Research trajectory: The defining scientific controversy for this compound has been simple and stubborn: does oral glutathione do anything? The sceptical position — that a tripeptide is hydrolysed in the gut to its constituent amino acids and never reaches the bloodstream intact — was long the mainstream view, and early human studies supported it. A six-month randomized controlled trial substantially changed that picture, and this page reports both sides. Commercial source: Fermentation-produced glutathione in reduced, oxidized, and liposomal formats.

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Evidence for L-Glutathione Applications

The oral bioavailability question is the central issue and has a specific, citable answer. A six-month randomized, double-blinded, placebo-controlled trial of oral glutathione (250 or 1,000 mg/day) in 54 non-smoking adults measured GSH in blood, erythrocytes, plasma, lymphocytes, and exfoliated buccal mucosal cells; GSH levels in blood increased after 1, 3, and 6 months versus baseline at both doses, and at 6 months mean GSH increased 30–35% in erythrocytes, plasma, and lymphocytes and 260% in buccal cells in the high-dose group (Richie 2015). The paper opens by stating plainly that while oral GSH is bioavailable in animal models, its efficacy in humans had not been established — which is a fair summary of where the field stood. Claim strength: Moderate.

The controversy is not fully closed, and it would be dishonest to present it as such. Results from human trials of oral GSH supplementation have been contrasting and debatable: other work reported that oral GSH in healthy adults did not change GSH levels or other oxidative-stress biomarkers, whereas the trial above found significant increases in body stores. The discrepancies have been attributed to differences in dose, duration, and — importantly — measurement of GSH in plasma rather than the erythrocyte fraction, where GSH turns over rapidly. A formulator should present oral glutathione as plausibly effective at raising body stores over months, not as settled science. Claim strength: Moderate.

The mechanistic significance of glutathione is not in dispute, and it is genuinely central rather than a marketing conceit. GSH is the most abundant endogenous low-molecular-weight thiol antioxidant and the principal intracellular redox buffer; it serves as the cofactor for glutathione peroxidase in reducing hydrogen peroxide and lipid peroxides, is the substrate for the glutathione S-transferase family in phase II conjugative detoxification of xenobiotics and carcinogens, regulates protein function through S-glutathionylation, and supports immune function. Endogenous GSH declines with age and in chronic disease. Claim strength: High (established biochemistry).

Delivery-format claims deserve interrogation rather than acceptance. Liposomal, micellar, sublingual, and orobuccal glutathione formats have all been reported as effective at restoring body stores, and a randomised crossover trial in healthy adults compared a micellar glutathione formulation against standard and liposomal glutathione using baseline-adjusted pharmacokinetic parameters. The buccal-cell result in the six-month trial — a 260% increase, far exceeding the 30–35% seen systemically — is itself suggestive that local oral-mucosal exposure may be doing considerable work. Formulators should demand comparative pharmacokinetic data rather than accepting "enhanced absorption" as a bare assertion. Claim strength: Emerging.

An alternative strategy that formulators should be aware of, because it is a genuine competitor to direct GSH supplementation: supplying precursors. Availability of cysteine is known to be rate-limiting for glutathione synthesis, and it is well documented both clinically and in animal studies that cysteine supplementation — most practically achieved by administering N-acetylcysteine — can boost glutathione synthesis and levels; glycine availability may likewise modulate synthesis, since tissue glycine levels sit below the Michaelis constant of human glutathione synthase for glycine (McCarty 2018). This route sidesteps the absorption controversy entirely by letting the body build the tripeptide itself. Whether direct GSH or precursor loading is the better commercial proposition is a legitimate open question, and a supplier who pretends otherwise is overselling. Claim strength: Moderate.

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Dosage & Formulator Specification

Herbuno carries L-Glutathione (Reduced) powder, L-Glutathione Oxidized, and Liposomal L-Glutathione powder. The reduced (GSH) and oxidized (GSSG) forms are distinct products and are not interchangeable: GSH carries the free reactive thiol, while GSSG is the disulfide-linked dimer. Buyers should specify which form their formulation requires.

Oral dosing in the pivotal six-month trial used 250 or 1,000 mg/day, with both doses raising blood GSH and the higher dose producing the larger tissue increases; benefit accrued progressively across 1, 3, and 6 months rather than acutely, which has a direct labelling implication — this is not an ingredient that should be presented as producing a same-day effect. Reduced glutathione is air-sensitive and is not stable at high water activity, so formulation moisture control and packaging matter more here than for most powders. Formulators should also be aware that GSSG taken orally has been reported to be reduced to GSH in the upper small intestine, which complicates the assumption that only the reduced form is worth supplying.

Analytical verification should specify GSH by HPLC (typically ≥98%) and, critically, should report the oxidized (GSSG) fraction alongside it — reduced glutathione air-oxidises, and a material assayed as high-purity GSH at manufacture may carry substantial GSSG by the time it is used. Storage under desiccating conditions with oxygen exclusion, at 2–8°C, should be specified and documented, and stability data across the intended shelf life is a reasonable demand rather than an unusual one. For liposomal and micellar formats, the carrier system, encapsulation efficiency, and — ideally — comparative pharmacokinetic data should be requested rather than assumed.

Glutathione is an endogenous human metabolite and is well tolerated; the six-month trial at 1,000 mg/day reported it as safe, and adverse effects at supplement intakes are minimal. Two points deserve statement. First, glutathione is a substrate for phase II conjugative detoxification, and there is a theoretical basis for interaction with drugs metabolised by glutathione S-transferases — this is not well characterised clinically but is a reasonable caution alongside chemotherapy in particular, where altering conjugative capacity is not a neutral act and medical supervision is essential. Second, the skin-lightening use of intravenous glutathione, widespread in some markets, has been the subject of regulatory warnings regarding unapproved parenteral products and is outside the scope of any legitimate oral supplement positioning.

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Frequently Asked Questions — L-Glutathione

Does oral glutathione actually work?
A six-month randomized, double-blind, placebo-controlled trial in 54 adults found that oral GSH at 250 or 1,000 mg/day raised blood GSH at 1, 3, and 6 months, with 30-35% increases in erythrocytes, plasma, and lymphocytes at the higher dose. That substantially changed the picture. But other trials found no change, and the discrepancies remain debated — present it as plausibly effective over months, not as settled.

What is the difference between reduced and oxidized glutathione?
GSH (reduced) carries the free reactive thiol and is the active redox form. GSSG (oxidized) is the disulfide-linked dimer. They are distinct products, not interchangeable. Complicating things, oral GSSG has been reported to be reduced back to GSH in the upper small intestine — so the assumption that only the reduced form is worth supplying may be too simple.

Is liposomal glutathione better?
Possibly, but demand data rather than accepting the claim. Liposomal, micellar, sublingual, and orobuccal formats have all been reported as effective, and comparative pharmacokinetic trials exist. Notably, the six-month trial found a 260% rise in buccal cells versus 30-35% systemically — suggesting local oral-mucosal exposure may be doing considerable work.

Should I supply glutathione or its precursors?
A legitimate open question, and a supplier who pretends otherwise is overselling. Glutathione synthesis is rate-limited by cysteine availability, and N-acetylcysteine, whey protein, and glycine have all been shown to raise GSH synthesis rates. That route sidesteps the absorption controversy entirely by letting the body build the tripeptide itself.

Related compounds: Alpha-Lipoic Acid, Betaine, Curcumin, Quercetin

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Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.

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