Quick summary
Glutathione (GSH) is the body's most abundant endogenous antioxidant tripeptide, central to redox regulation, detoxification, and immune function. Oral bioavailability is poor; IV and liposomal formulations are used for systemic elevation, while NAC serves as a common oral precursor.
Overview
Glutathione (GSH) is the body's most abundant endogenous antioxidant tripeptide, composed of glycine, cysteine, and glutamate. It is present in virtually all mammalian cells at millimolar concentrations and serves as a central hub of cellular redox regulation. GSH acts as a direct scavenger of reactive oxygen species, a cofactor for glutathione peroxidase enzymes, and a regenerator of vitamins C and E. Its depletion is associated with aging, chronic disease, and metabolic dysfunction.
Mechanism of action
Glutathione exerts antioxidant action through two main mechanisms: direct chemical quenching of reactive oxygen and nitrogen species, and enzymatic reduction of lipid hydroperoxides via glutathione peroxidase (GPx). It maintains cellular redox balance by cycling between reduced (GSH) and oxidized (GSSG) forms, with more than 90% normally in the reduced state. GSH conjugates electrophilic toxins via glutathione S-transferase for hepatic detoxification, maintains exogenous antioxidants in active states, and supports immune lymphocyte function. It also modulates apoptosis and inflammatory signaling through thiol chemistry.
Dosing protocols
| Purpose | Route | Dosage | Frequency | Notes |
|---|---|---|---|---|
| antioxidant / immune support (oral) | oral | 250–1000 mg | once daily | Oral bioavailability is limited. Liposomal formulations may improve absorption. Consider NAC as a precursor alternative. |
| systemic GSH elevation (IV) | intravenous | 600–1200 mg | 1-3x per week | IV infusion under clinical supervision. Used in functional medicine and anti-aging protocols. |
Dosing information is for educational purposes only. Consult a qualified healthcare professional before using any peptide.
Research summary
Extensive basic research confirms GSH's central role in oxidative stress defense, detoxification, and immune function. Oral bioavailability is poor due to GI peptidase hydrolysis; IV administration reliably raises plasma and tissue GSH levels. A 2011 human study showed modest systemic oxidative stress reduction with oral supplementation at 250 mg/day. N-acetylcysteine (NAC) is commonly used as a GSH precursor with superior oral bioavailability. IV GSH is used clinically in some contexts as an adjunct to cancer chemotherapy to reduce oxidative side effects.[1][2][3][4][5]
Evidence grading
Each claimed benefit is graded by the strength of available evidence. Grades reflect study quality, not effect size.
Strong = multiple RCTs · Moderate = limited trials or observational · Preliminary = animal or in vitro only · Insufficient = anecdotal or no published data
Side effects
Side effects vary by individual. This is not an exhaustive list. Report unusual symptoms to a healthcare professional.
Common stacks
Peptides commonly paired with Glutathione for synergistic effects.
Legal status
Available OTC as oral dietary supplement. IV formulations used in some clinical and cosmetic (skin-brightening) contexts. Oral supplementation widely available; IV typically requires clinic administration.
Sourcing & access
Research compound
Glutathione is classified as a research compound. Regulatory status varies by jurisdiction. Always verify current legal status and source from vendors providing third-party certificates of analysis (COA).
Frequently asked questions
Glutathione is a tripeptide (glycine, cysteine, glutamate) present in virtually all mammalian cells at millimolar concentrations. It is the central hub of cellular redox regulation, acting as a direct free radical scavenger, enzyme cofactor, and regenerator of vitamins C and E.
Oral bioavailability is poor due to GI peptidase hydrolysis. IV administration reliably raises plasma and tissue levels. Liposomal oral formulations may improve absorption. N-acetylcysteine (NAC) is commonly used as a glutathione precursor with superior oral bioavailability.
Oral supplementation ranges from 250 to 1000 mg daily. IV protocols typically use 600 to 1200 mg administered 1 to 3 times per week under clinical supervision. Oral supplementation is often paired with vitamin C to support recycling.
Chronic IV glutathione use has been associated with skin lightening effects, which has led to its use in cosmetic contexts in some countries. This effect is a side effect of its antioxidant activity on melanin pathways rather than an approved medical indication.
Oral glutathione supplements are generally well tolerated, with bloating at high doses being the most common complaint. IV administration has rare hypersensitivity reactions. It is available OTC as a dietary supplement with no prescription required.
Research references
- Randomized controlled trial of oral glutathione supplementation on body stores of glutathionePubMed
- Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune functionPubMed
- Randomized Clinical Trial of How Long-Term Glutathione Supplementation Offers Protection from Oxidative Damage and Improves HbA1c in Elderly Type 2 Diabetic PatientsPubMed
- The Role of Glutathione Metabolism in Chronic Illness Development and Its Potential Use as a Novel Therapeutic TargetPubMed
- Effects of N-acetylcysteine, oral glutathione (GSH) and a novel sublingual form of GSH on oxidative stress markers: A comparative crossover studyPubMed