Last verified: 17 days ago
L-Glutathione
Also known as: GSH, reduced glutathione, L-GSH, reduced L-glutathione, gamma-glutamylcysteinylglycine
Evidence under review. — Not yet rated
Antioxidant tripeptide. Some evidence for skin lightening, gut health in CF, and liver support when combined with diet.
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What it does
L-Glutathione is a naturally occurring antioxidant tripeptide made from three amino acids. Clinical trials suggest it may lighten skin and reduce dark spots when combined with L-Cystine, improve...
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Evidence quality
Evidence base hasn't been formally rated yet. See research below.
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Clinical dose
65 mg/kg/day (pediatric CF); 250 mg/day (skin lightening combo); sublingual dosing studied for cardiovascular
What the Science Says
L-Glutathione is a naturally occurring antioxidant tripeptide made from three amino acids. Clinical trials suggest it may lighten skin and reduce dark spots when combined with L-Cystine, improve growth and gut inflammation in children with cystic fibrosis, and support liver health alongside a Mediterranean diet. A sublingual form showed modest effects on cholesterol and vascular function in people with cardiovascular risk factors.
What It Doesn't Do
Not proven to detox your body on its own — your liver already makes glutathione. No evidence it boosts athletic performance or builds muscle. Oral pills alone don't reliably raise blood glutathione levels. Not a standalone treatment for any disease. Most dramatic anti-aging claims are not backed by the studies available.
Evidence-Based Benefits
Reduces skin darkness and facial dark spot size in Asian women when combined with L-Cystine over 12 weeks.
Weak EvidenceEffective at: 250 mg/day L-Glutathione + 500 mg/day L-Cystine
Supporting studies (click to view on PubMed):
Improves weight, BMI, and height in children with cystic fibrosis over 6 months.
Weak EvidenceEffective at: 65 mg/kg/day divided into 3 doses
Supporting studies (click to view on PubMed):
May reduce liver steatosis in overweight adults with NAFLD when added to a Mediterranean diet.
Weak EvidenceEffective at: No data from provided studies (used as part of multi-ingredient formula)
Supporting studies (click to view on PubMed):
Sublingual glutathione may lower LDL cholesterol and improve arterial stiffness in people with cardiovascular risk factors.
Weak EvidenceEffective at: No data from provided studies (sublingual formulation, dose not specified)
Supporting studies (click to view on PubMed):
Absorption & Bioavailability
Poor to Moderate — standard oral glutathione is poorly absorbed intact through the gut. Sublingual delivery may improve absorption by bypassing first-pass metabolism. Combining with L-Cystine may enhance effects. Absorption data from provided studies is limited.
Red Flags to Watch For
- Oral bioavailability is a known problem — many products may not raise blood glutathione levels meaningfully
- Skin-lightening claims are popular in marketing but only one small RCT (in Asian women) supports this use
- Most NAFLD/liver studies used glutathione as part of a multi-ingredient formula, making it impossible to isolate its effect
- High-dose use in children (65 mg/kg/day) was studied in a specific disease context — do not generalize to healthy kids
- Products marketed for 'detox' or 'immune boosting' have no direct support from the provided clinical evidence
Products Containing L-Glutathione
See how L-Glutathione is used in these analyzed products:
Halo Beauty Hair Skin Nails Booster
Supplement
Smartvita Men's Total Synergy Multivitamins
Supplement
Cymbiotika Liposomal Glutathione
Supplement
Vitabiotics Neuromind Plus
Supplement
Transparent Labs Nitric Oxide
Supplement
Smartvita Women's Total Synergy Multivitamins
Supplement
NutraBio Liver
Supplement
Frequently Asked Questions
What does L-Glutathione do?
Antioxidant tripeptide. Some evidence for skin lightening, gut health in CF, and liver support when combined with diet.
What is the effective dose of L-Glutathione?
65 mg/kg/day (pediatric CF); 250 mg/day (skin lightening combo); sublingual dosing studied for cardiovascular
Is L-Glutathione safe?
Oral bioavailability is a known problem — many products may not raise blood glutathione levels meaningfully
What doesn't L-Glutathione do?
Not proven to detox your body on its own — your liver already makes glutathione.
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-05-25