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Glutathione (reduced L-glutathione, GSH)
The body's main intracellular antioxidant; supplemental forms are best studied for skin-lightening, with debated oral bioavailability for systemic effects.
What the evidence says
Most Glutathione studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from high-quality meta-analyses and randomised trials published 2011–2026 with a typical study size of 1,019 participants.
Based on 14 studies · 1 meta-analysis · 10 RCTs · 1,073 total participants
Confidence
HighBy outcome
Glutathione has an evidence score of 5.2/10 — moderate evidence based on 14 indexed studies. The body's main intracellular antioxidant; supplemental forms are best studied for skin-lightening, with debated oral bioavailability for systemic effects. Representative study: PMID 39444151.
The commonly studied dose of Glutathione is 250-1000mg/day oral reduced L-glutathione (skin-lightening trials often used ~500mg); liposomal/sublingual forms aim to improve absorption. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
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Last reviewed June 2026 · evidence from 14 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
Glutathione (GSH) is a tripeptide (glutamate-cysteine-glycine) and the body's principal intracellular antioxidant, central to detoxification and redox balance in the liver and elsewhere. As a supplement it's marketed for antioxidant support, skin brightening, and detox. The catch is oral bioavailability: glutathione is broken down in the gut, so raising tissue levels by swallowing it is debated — the most consistent clinical effect is modest skin-lightening, and some trials in specific conditions (e.g. cystic fibrosis growth) are mixed. Notably, supplying its precursors (cysteine via NAC, plus glycine — 'GlyNAC') often raises glutathione more reliably than glutathione itself.
Directly neutralizes reactive oxygen species and regenerates other antioxidants (vitamins C and E).
A cofactor for glutathione-S-transferases that conjugate and clear toxins and drug metabolites, especially in the liver.
Inhibits tyrosinase and shifts melanin toward lighter pheomelanin, the basis of its skin-lightening effect.
250-1000mg/day oral reduced L-glutathione (skin-lightening trials often used ~500mg); liposomal/sublingual forms aim to improve absorption
Can be taken without food
| Form | Type |
|---|---|
| 💊Liposomal or sublingual glutathione (for absorption) | Recommended |
| 💊Plain oral reduced L-glutathione | Alternative |
| 💊Precursors (NAC + glycine / GlyNAC) | Alternative |
If the goal is systemic glutathione, precursors (NAC + glycine) are often more effective than oral GSH.
Minimum: 4 weeks
Optimal: 12 weeks
Cycling: Not required
Note: Commonly taken on an empty stomach; liposomal forms are flexible.
Dose-response data unavailable. The current published research for Glutathione does not provide sufficient dose-specific outcome data to generate reliable dose-response curves.
Refer to the Dosage & Timing section above for recommended dose ranges based on available evidence.
Modestly lightens skin and improves melasma; effect is often temporary.
May lower some oxidative-stress markers; systemic effect limited by oral bioavailability.
Oral glutathione is largely broken down in the gut; precursors (GlyNAC) may raise levels more reliably.
Discuss with your oncologist before using antioxidants.
Not well studied at supplemental doses — avoid without medical advice.
Antioxidants may theoretically interact with pro-oxidant chemotherapy — coordinate with your oncologist.
Tip: Take with a little food; reduce dose
Tip: Expected; reverses after stopping
NAC supplies cysteine, the rate-limiting precursor for glutathione synthesis — often more effective than oral glutathione for raising levels.
More reliable increase in endogenous glutathione.
Glycine is a glutathione building block; with NAC ('GlyNAC') it raises glutathione and improves several aging markers in trials.
GlyNAC reliably restores glutathione in older adults.
ALA helps regenerate glutathione and other antioxidants.
Broader antioxidant/redox support.
Vitamin C helps recycle oxidized glutathione back to its active form.
Mutually regenerating antioxidant pair.
The best time to take Glutathione is between meals. It can be taken on an empty stomach. Often taken on an empty stomach; liposomal/sublingual forms are used to limit gut breakdown.
Glutathione is generally well-tolerated and considered safe for most healthy adults at recommended doses. The most commonly reported side effects are mild GI upset, transient skin lightening (intended effect). Use caution if any of these apply to you: Known glutathione/sulfur supplement hypersensitivity.
Hydrolyzed peptides that rebuild skin elasticity, reduce joint pain, and strengthen bone density — results build over 8-12 weeks.