Glutathione
GSH / S-acetyl glutathione / liposomal glutathione · Longevity
The body's master antioxidant, heavily marketed injectable and oral, with an absorption story more complicated than the labels admit.
What it is
A tripeptide (three amino acids, glutamate, cysteine and glycine, joined together) that your body builds and keeps in nearly every cell. It is not a vitamin: you make your own continuously, and the liver holds the largest pool. Supplements exist because that pool falls with age, illness and heavy alcohol use, and because the marketing around skin lightening and "detox" is relentless.
How it works
Glutathione is the cell's reusable electron donor. It neutralises reactive molecules, then an enzyme recharges it so it can work again, which is why the ratio of charged to spent glutathione is used as a redox health marker. It also does the unglamorous job of phase II liver detoxification: it latches onto certain drugs and toxins to make them water-soluble enough to excrete. The supplement question is not whether it matters (it plainly does) but whether swallowing it raises what your cells actually hold.
Which form to buy
The form used in the 54-person six-month randomised trial that reported raised body stores at 250 and 1,000 mg/day, with some compartments rising by one month. A four-week trial in 40 adults measuring red-cell glutathione and urinary oxidative-stress markers found no change, which is where the "it is destroyed in the gut" claim comes from.
The best-studied oral option, and the one the principal long randomised trial used.
An acetyl group is added to survive digestion. One very small head-to-head crossover study compared single doses against plain glutathione on blood levels; nothing has compared them on a health outcome.
Plausible, more expensive, and not shown to work better where it counts.
Encased in fat vesicles to slip past gut breakdown. Small crossover studies have compared standard, liposomal and micellar forms on blood levels, with the micellar form coming out ahead in one; these are single-dose absorption studies with commercial involvement, not outcome trials.
Reasonable if you like the format. No form has been shown to produce a better health result.
Not glutathione at all, it supplies cysteine, the rate-limiting ingredient your body uses to build its own. Far more human data than glutathione itself, and it is a hospital drug for paracetamol overdose.
The precursor route is better evidenced than the direct one. Frequently conflated with glutathione on labels.
Popular for skin lightening. No injectable glutathione product is FDA-approved. US regulators have flagged compounded sterile injectables specifically over endotoxin contamination, with reported fever, chills, vomiting, low blood pressure, breathing difficulty and hospitalisation, and a 2026 recall warned of severe hypotension, anaphylactic shock and death. The Philippine regulator has separately warned against injectable use for skin whitening.
The weakest evidence and by far the highest risk in the category. Avoid.
What it actually does, graded
A 54-person six-month randomised trial reported increased stores at 250 and 1,000 mg/day, with some compartments rising by one month. A four-week trial found no change on red-cell and urinary markers, which explains the contradictory reputation.
Not in question. Glutathione conjugation is established biochemistry.
A separate claim from the one above, and the trials to support it in a healthy liver have not been done.
Reported in small trials, with the usual caveat that a moved biomarker is not a moved outcome.
Small oral randomised trials have reported modest reductions in skin melanin at some measurement sites but not others, and reviews describe the evidence as inconsistent, at risk of bias, and without durable benefit. None of it justifies the injectable market built on top of it.
No human trial has tested this. Stores decline with age, which is an observation, not a demonstrated lever.
Pros and cons
- One of the few antioxidants with a genuine, central role in human biochemistry rather than a marketing one
- A six-month randomised trial supports oral use actually reaching body stores
- Well tolerated at studied oral doses
- The precursor route (NAC) is cheap and much better evidenced if the goal is raising your own
- Hard outcome data (skin, energy, longevity) is close to absent
- The absorption debate is genuinely unsettled and brands exploit it
- Premium forms charge for theory rather than head-to-head evidence
- The injectable market around it is unregulated and carries real harm reports
What to expect
- Weeks 1-4: nothing perceptible. This is a biochemical pool, not a stimulant, and no trial reports a felt effect on this timescale.
- Months 1-6: the trial that reported raised stores ran six months, with some compartments rising by month one. If your goal is repletion, that is the timescale to think in.
- Skin lightening: not an expectation this page will set. The evidence does not support it and the injectable route carries regulator warnings.
Interactions
Is it for you?
- You want the biochemistry supported and are content with a slow, unfelt repletion goal
- You are curious about the pathway but would rather take the better-evidenced precursor, read NAC first
- You are buying it to lighten skin, that use is unsupported and the injectable form carries regulator warnings
- You expect to feel something; no trial reports a perceptible short-term effect
- You are already taking NAC, which works on the same pathway from the precursor end
Who should avoid it
- Anyone considering injectable glutathione from an unregulated source
- Anyone in active cancer treatment, without their oncologist signing off
Research on this supplement
Papers about this supplement, not proof of the claims above. A title says what was studied, which is sometimes a negative result or a different question entirely.
- Glutathione as a skin-lightening agent and in melasma: a systematic review
- Impact of malaria on glutathione peroxidase levels: a systematic review and meta-analysis
- The clinical effect of glutathione on skin color and other related skin conditions: A systematic review
What the evidence says
Oral bioavailability findings are mixed, some short studies found little serum change, while at least one six-month randomized trial reported increased body stores with ordinary oral glutathione. Hard outcome data (skin, detox, longevity) is thin; the popular skin-lightening use rests on the weakest evidence and the most aggressive marketing.
What studies used
Published oral trials have used 250-1,000 mg/day. Published trials dosed daily without establishing a preferred time.
Reported from published studies and product labelling — a record of what was used in research, not a recommendation. What is right for you is a conversation with a clinician.
Watch out for
- Injectable vials from unregulated sources carry sterility risk, this category enters the same needle as everything else sold beside it
- NAC, a precursor, has its own separate absorption evidence, the two are often conflated in marketing
Evidence base
established literature
Large human evidence base: several phase 3 or 4 trial reports, plus multiple meta-analyses or systematic reviews.
This letter measures how much human research exists, not whether it works for you — the tier above (Limited) is the read on quality.
Research (12)
- Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune functionEur J Clin Nutr · 2018
- Oral delivery of therapeutic peptides and proteins: Technology landscape of lipid-based nanocarriersAdv Drug Deliv Rev · 2022
- The clinical effect of glutathione on skin color and other related skin conditions: A systematic reviewJ Cosmet Dermatol · 2019
- Bioavailability and metabolismMol Aspects Med · 2002
- Oral Exposure of Arsenic-Contaminated Soils Triggers Hepatic Ferroptosis via Iron Dysregulation and Glutathione Metabolism Disruption: From Bioavailability to MechanismsEnviron Sci Technol · 2025
- Curcumin: the story so farEur J Cancer · 2005
- Enhanced oral bioavailability and in vivo antioxidant activity of chlorogenic acid via liposomal formulationInt J Pharm · 2016
- Design of novel proliposome formulation for antioxidant peptide, glutathione with enhanced oral bioavailability and stabilityDrug Deliv · 2019
- Development of Poly(lipoic acid) Nanoparticles with Improved Oral Bioavailability and Hepatoprotective Effects of QuercetinMol Pharm · 2022
- Ginsenoside F2-modified liposomes delivering FTY720 enhance glioblastoma targeting and antitumor activity via ferroptosisPhytomedicine · 2025
- Liposomal-glutathione provides maintenance of intracellular glutathione and neuroprotection in mesencephalic neuronal cellsNeurochem Res · 2010
- Nano-Structured Lipid Carrier-Based Oral Glutathione Formulation Mediates Renoprotection against Cyclophosphamide-Induced Nephrotoxicity, and Improves Oral Bioavailability of Glutathione Confirmed through RP-HPLC Micellar Liquid ChromatographyMolecules · 2021
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