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Glutathione
Glutathione is the body's most abundant intracellular antioxidant, and the supplement industry has built a large category around the idea that you can swallow it and raise your levels.
- Evidence
- Weak Evidence
- Category
- Immune Support
- Best form
- Setria reduced glutathione (Kyowa Hakko branded, used in the Richie 2015 dose-response trial and the Sinha immune study)
- Effective dose
- Setria reduced glutathione trials used 250-1000mg/day for 6 months. Liposomal and S-acetyl forms have no agreed clinical dose and limited RCT support.
- Lab tested
- 4 of 8 products
- Category
- Immune Support
- Best form
- Setria reduced glutathione (Kyowa Hakko branded, used in the Richie 2015 dose-response trial and the Sinha immune study)
- Effective dose
- Setria reduced glutathione trials used 250-1000mg/day for 6 months. Liposomal and S-acetyl forms have no agreed clinical dose and limited RCT support.
- Lab tested
- 4 of 8 products
Key takeaways
- →Oral bioavailability is the central problem - free GSH gets hydrolyzed in the gut. Setria at 1000mg/day x 6 months can raise blood GSH ~30-35% (Richie 2015), but smaller doses and shorter trials often show no change.
- →Liposomal glutathione has plausible PK advantages over free GSH but heterogeneous brand-by-brand data and few functional outcome trials. S-acetyl GSH has almost no human RCT base.
- →Skin lightening claims rely mostly on IV glutathione data and small short-duration oral trials. Not a regulated supplement claim and the evidence is weak.
- →For raising intracellular glutathione, NAC is the better-evidenced and far cheaper option - it provides the rate-limiting cysteine precursor with decades of pharmacology behind it.
What Is Glutathione?
Glutathione is the body's most abundant intracellular antioxidant, and the supplement industry has built a large category around the idea that you can swallow it and raise your levels. The honest answer is that you can - barely, with the right form, and the downstream functional outcomes are mostly weak.
Start with the bioavailability problem, because it is the single most important consumer decision factor. Free reduced glutathione (GSH) is a tripeptide of glutamate, cysteine, and glycine. The GI tract has gamma-glutamyltransferase and other peptidases that hydrolyze most oral GSH back into amino acids before it crosses the intestinal wall. For decades the textbook position was that oral glutathione "doesn't work."
The 2015 Richie trial (n=54, 6 months, Setria oral GSH at 250mg/day or 1000mg/day) was the first well-controlled RCT to push back on that. At 1000mg/day, erythrocyte, plasma, and lymphocyte GSH rose about 30-35% over six months and natural killer cell cytotoxicity roughly doubled at the 3-month mark. At 250mg/day the effects were smaller (17-29%). Levels returned to baseline within a month of stopping. This is real but modest, requires a high daily dose, and used a specific branded form (Setria from Kyowa Hakko).
A separate 2018 trial by the same lab in Setria-supplemented adults reported improvements in NK cytotoxicity and some inflammatory markers, again with modest effect sizes. A 2011 trial by Allen and Bradley (n=40, 500mg twice daily x 4 weeks) found no significant change in oxidative stress biomarkers or red cell GSH - probably because the duration was too short for the slow uptake pattern Richie later documented.
Liposomal glutathione gets the most marketing attention. The pitch is that phospholipid encapsulation protects GSH from GI hydrolysis. Small PK studies do suggest better plasma rises than free GSH at lower doses, but the data are heterogeneous, the trials are small, and the formulations vary substantially between brands (Quicksilver, Pure Encapsulations, ProHealth, Bulletproof all use different liposome chemistries). Functional outcome trials are sparse. S-acetyl glutathione is in a worse position - good mechanistic rationale, almost no human RCT base.
The downstream functional claims are where marketing outruns evidence. Skin lightening is the biggest commercial driver, particularly in Asian markets, but the strongest signals are from IV glutathione (outside the supplement scope) and the small oral RCTs are short, often industry-funded, and inconsistent. Fatty liver, Parkinson's, autism, and chronic fatigue all have small open-label signals and no replicated, well-powered trials.
The practical bottom line: if you specifically want to raise blood GSH, Setria at 1000mg/day for several months has the cleanest evidence, and you should expect a 30-35% rise rather than a transformation. If you want a better-evidenced way to support intracellular glutathione, take NAC - it provides the rate-limiting precursor (cysteine), has decades of pharmacology behind it, costs a fraction as much, and has stronger clinical outcome data (COPD exacerbations, OCD, PCOS) than any oral GSH product. For most readers, NAC is the smarter purchase.
Does It Work? The Evidence
How A-F grades workRaises blood and tissue glutathione stores (reduced GSH, oral)
Richie 2015 RCT (n=54, Setria GSH 250 or 1000mg/day x 6 months): 30-35% rise in erythrocyte/plasma/lymphocyte GSH at the high dose, smaller rise at the low dose, baseline within 1 month of stopping. Allen 2011 RCT (n=40, 500mg twice daily x 4 weeks): no significant change, likely underpowered and too short.
Liposomal glutathione bioavailability advantage over free GSH
Small PK studies suggest liposomal formulations raise plasma GSH at lower oral doses than free reduced GSH, but trials are heterogeneous, brand-specific, and rarely measure functional endpoints. No head-to-head RCT against Setria at clinical doses.
S-acetyl glutathione resistance to GI hydrolysis
Mechanistic rationale (acetylation slows peptide hydrolysis) is reasonable but human RCT data is essentially absent. Most marketing claims trace back to in vitro and animal work.
Natural killer cell function and immune support
Richie 2015 reported ~2x rise in NK cytotoxicity at 1000mg/day Setria at 3 months. Follow-up Setria-sponsored work has reported related immune markers. Single research group, modest effect sizes, no large independent replication.
Skin lightening and brightening
Strongest melanin-reduction signals come from IV glutathione (not a supplement). Small oral RCTs in Asian populations have shown modest melanin index changes at 250-500mg/day over 4-12 weeks, but trials are short, often industry-funded, and use varying skin-assessment methods. FDA does not permit skin lightening claims on supplements.
Non-alcoholic fatty liver disease (NAFLD)
Small open-label Japanese trial (Honda et al. 2017) reported ALT reductions on 300mg/day. Not replicated in larger blinded RCTs. NAC has more data here.
Parkinson's disease, autism, chronic fatigue, oxidative stress generally
Scattered small trials and open-label series, mostly with IV or intranasal GSH rather than oral. Oral supplement evidence is preliminary across the board.
| Grade | Claimed Benefit | Key Studies | Our Verdict |
|---|---|---|---|
| B | Raises blood and tissue glutathione stores (reduced GSH, oral) | Richie 2015 RCT (n=54, Setria GSH 250 or 1000mg/day x 6 months): 30-35% rise in erythrocyte/plasma/lymphocyte GSH at the high dose, smaller rise at the low dose, baseline within 1 month of stopping. Allen 2011 RCT (n=40, 500mg twice daily x 4 weeks): no significant change, likely underpowered and too short. | Early Signal |
| C | Liposomal glutathione bioavailability advantage over free GSH | Small PK studies suggest liposomal formulations raise plasma GSH at lower oral doses than free reduced GSH, but trials are heterogeneous, brand-specific, and rarely measure functional endpoints. No head-to-head RCT against Setria at clinical doses. | Early Signal |
| D | S-acetyl glutathione resistance to GI hydrolysis | Mechanistic rationale (acetylation slows peptide hydrolysis) is reasonable but human RCT data is essentially absent. Most marketing claims trace back to in vitro and animal work. | Not There Yet |
| C | Natural killer cell function and immune support | Richie 2015 reported ~2x rise in NK cytotoxicity at 1000mg/day Setria at 3 months. Follow-up Setria-sponsored work has reported related immune markers. Single research group, modest effect sizes, no large independent replication. | Early Signal |
| C | Skin lightening and brightening | Strongest melanin-reduction signals come from IV glutathione (not a supplement). Small oral RCTs in Asian populations have shown modest melanin index changes at 250-500mg/day over 4-12 weeks, but trials are short, often industry-funded, and use varying skin-assessment methods. FDA does not permit skin lightening claims on supplements. | Not There Yet |
| D | Non-alcoholic fatty liver disease (NAFLD) | Small open-label Japanese trial (Honda et al. 2017) reported ALT reductions on 300mg/day. Not replicated in larger blinded RCTs. NAC has more data here. | Not There Yet |
| D | Parkinson's disease, autism, chronic fatigue, oxidative stress generally | Scattered small trials and open-label series, mostly with IV or intranasal GSH rather than oral. Oral supplement evidence is preliminary across the board. | Not There Yet |
How to Choose: Forms, Doses & What Matters
Clinical dose: Setria reduced glutathione trials used 250-1000mg/day for 6 months. Liposomal and S-acetyl forms have no agreed clinical dose and limited RCT support.
Best forms: Setria reduced glutathione (Kyowa Hakko branded, used in the Richie 2015 dose-response trial and the Sinha immune study), Liposomal glutathione (phospholipid-encapsulated; PK data suggests better absorption than free GSH but is heterogeneous and brand-variable), S-acetyl glutathione (acetylated form claimed to resist GI hydrolysis; very thin human RCT base), NAC (N-acetyl cysteine) as an upstream precursor with much stronger evidence for actually raising intracellular glutathione - see our NAC profile
For the Richie 2015 protocol, 1000mg/day of Setria reduced glutathione, split or as a single dose, for at least 3-6 months. Food does not appear to make a major difference but most users tolerate it better with a meal. For liposomal forms, follow the brand's label - typical doses run 350-500mg/day and the liquid is taken sublingually for a short hold before swallowing. Effects on blood GSH levels are slow (Richie reported significant rises by 1 month but full effect by 6 months) and disappear within about a month of stopping, so consistent daily dosing matters more than precise timing. If you are taking NAC and oral glutathione together, dose them at separate times of day to avoid GI side effect stacking.
Who Should Take Glutathione?
People specifically targeting blood glutathione elevation who are willing to commit to a Setria-branded product at 1000mg/day for at least 3-6 months (the Richie 2015 protocol). People who have already tried NAC and want to add or compare a direct GSH approach. People taking high oxidative stress loads (smoking, heavy alcohol, occupational toxin exposure) who want a glutathione-targeted intervention under physician guidance. Anyone curious about liposomal forms should treat them as experimental and stick to brands with published PK or COA data.
Who Should Avoid It?
Not for everyone
Side Effects & Safety
Product Scores
8 products scored on dosing accuracy, third-party testing, cost per effective dose, and label transparency.
The Scorecard: 8 Products Compared
Reduced Glutathione 500mg, 60 Veggie Caps
Jarrow Formulas$22.95 ÷ 30 days at 1000mg/day (2 servings × 500mg)
The Setria form Jarrow uses is the same reduced glutathione tested in the Richie 2015 trial. If you specifically want the form with the cleanest published bioavailability data, this is the pick.
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
Glutathione 500mg with Milk Thistle & Alpha Lipoic Acid, 60 Veg Capsules
NOW Foods$32.99 ÷ 60 days at 500mg/day (1 serving × 500mg)
Setria GSH at the clinical dose plus a small ALA and milk thistle add. If you want a Setria product but also want some hepatic cofactors in the same cap, this is the cleaner buy than most stacks.
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
Glutathione 1000mg Equivalent (Setria), 120 Capsules
Toniiq
$26.99 ÷ 60 days at 1000mg/day (2 servings × 500mg)
Toniiq has been aggressive about publishing batch CoAs and is one of the most affordable ways to hit the Richie 1000mg/day Setria dose. The '1000mg equivalent' label phrasing refers to two-cap daily intake, not per-cap content.
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
Liposomal Glutathione, 60 Softgels
Pure Encapsulations$78.00 ÷ 60 days at 250mg/day (1 serving × 250mg)
The cleanest-tested liposomal GSH softgel on the market. Pay for the testing if quality verification matters more to you than hitting the Richie dose. To actually match clinical dosing you would be at 4 caps/day, which makes the per-day cost steep.
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
L-Glutathione Reduced 500mg, 60 Capsules
Nutricost$17.95 ÷ 60 days at 500mg/day (1 serving × 500mg)
If you accept that reduced GSH is the same molecule regardless of brand and you want the cheapest 500mg-per-cap option, Nutricost works. You are trading the Setria PK paper trail for a significantly lower cost.
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
Liposomal Glutathione, 3.38 fl oz (100 mL)
Quicksilver Scientific
$90.00 ÷ 50 days at 410mg/day (1 serving × 410mg)
The most-cited premium liposomal GSH brand. The phospholipid chemistry is real and the brand is transparent about formulation, but you are paying 3-4x what a Setria product costs for evidence that is thinner. Worth it only if you have specifically tried Setria and want to compare.
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
Liposomal Glutathione 450mg, 30 Servings
ProHealth
$32.95 ÷ 30 days at 450mg/day (1 serving × 450mg)
A reasonable mid-priced entry into liposomal GSH if Quicksilver's price tag is too steep. Just be honest with yourself that you are paying a premium over Setria capsules for a form with thinner outcome data.
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
S-Acetyl L-Glutathione 100mg, 60 Capsules
Double Wood Supplements$29.95 ÷ 60 days at 100mg/day (1 serving × 100mg)
If you want to experiment with S-acetyl GSH, Double Wood is a reasonable brand pick. But understand that the bioavailability advantage claim is mechanistic, not clinical, and there is no published S-acetyl trial comparable to Richie 2015.
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
Full Comparison
| Category | Reduced Glutathione 500mg, 60 Veggie Caps Jarrow Formulas | Glutathione 500mg with Milk Thistle & Alpha Lipoic Acid, 60 Veg Capsules NOW Foods | Glutathione 1000mg Equivalent (Setria), 120 Capsules Toniiq | Liposomal Glutathione, 60 Softgels Pure Encapsulations | L-Glutathione Reduced 500mg, 60 Capsules Nutricost | Liposomal Glutathione, 3.38 fl oz (100 mL) Quicksilver Scientific | Liposomal Glutathione 450mg, 30 Servings ProHealth | S-Acetyl L-Glutathione 100mg, 60 Capsules Double Wood Supplements |
|---|---|---|---|---|---|---|---|---|
| Brand Score | 86/100Winner | 82/100 | 78/100 | 76/100 | 70/100 | 70/100 | 68/100 | 64/100 |
| Dosing & Form | 23/25Winner | 22/25 | 22/25 | 19/25 | 22/25 | 18/25 | 16/25 | 13/25 |
| Purity | 19/25 | 16/25 | 13/25 | 21/25Winner | 10/25 | 16/25 | 13/25 | 19/25 |
| Value | 21/25 | 21/25 | 20/25 | 13/25 | 22/25Winner | 13/25 | 16/25 | 13/25 |
| Transparency | 23/25Winner | 23/25 | 23/25 | 23/25 | 16/25 | 23/25 | 23/25 | 19/25 |
| Cost/Day | $0.77 | $0.55 | $0.45 | $1.30 | $0.30Winner | $1.80 | $1.10 | $0.50 |
| Dose/Serving | 500mg | 500mg | 500mg | 250mg | 500mg | 410mg | 450mg | 100mg |
| Form | Setria Reduced Glutathione (vegetarian capsule) | Setria Reduced Glutathione + ALA + Milk Thistle (vegetable capsule) | Setria Reduced Glutathione (capsule) | Liposomal Glutathione (softgel) | Generic Reduced L-Glutathione (capsule) | Liposomal Glutathione (liquid) | Liposomal Glutathione (liquid) | S-acetyl L-glutathione (capsule) |
| Third-Party Tested | No | No | ✓ Yes | ✓ Yes | No | ✓ Yes | No | ✓ Yes |
| Proprietary Blend | No | No | No | No | No | No | No | No |
Frequently Asked Questions
Does oral glutathione actually work, or does it get destroyed in the stomach?
Both, partially. The older view was that oral GSH was useless because the GI tract hydrolyzes it. The Richie 2015 RCT showed that at 1000mg/day of Setria reduced glutathione for 6 months, blood, red cell, and lymphocyte GSH rose about 30-35%. So oral glutathione can raise body stores, but you need a high daily dose, the right branded form, and several months of consistent intake. Shorter or smaller trials have generally been negative (Allen 2011 at 1000mg/day for 4 weeks showed nothing). It is not a quick-acting supplement.
Glutathione vs NAC - which should I take?
For most people, NAC. NAC provides cysteine, the rate-limiting building block your body uses to synthesize glutathione inside cells. NAC has decades of clinical pharmacology, much better oral bioavailability, far stronger outcome data (COPD exacerbations, OCD, PCOS), and costs a fraction of what oral glutathione does. The case for direct oral glutathione is mainly that it can raise blood GSH measurably on the right dose-duration protocol, but the functional outcomes are not better-evidenced than NAC's. Practical rule: start with NAC. Consider oral glutathione if you have already tried NAC, want to specifically target blood GSH levels, or have a reason to avoid the sulfur smell of NAC.
Is liposomal glutathione really better absorbed than regular glutathione?
Plausibly yes, but the data is thinner than the marketing suggests. Liposomes are phospholipid vesicles that can protect GSH from GI hydrolysis, and small pharmacokinetic studies have shown plasma GSH rises at lower oral doses than free reduced GSH. The catch is that liposome quality varies dramatically between brands (Quicksilver, Pure Encapsulations, ProHealth, Bulletproof all use different formulations), few brands publish their own PK data, and functional outcome trials are sparse. If you want liposomal, pick brands that publish formulation and stability data. If you want the form with the most outcome data, that is still Setria reduced GSH at 1000mg/day.
What is Setria glutathione?
Setria is the branded reduced glutathione made by Kyowa Hakko, the Japanese pharma company that also makes Cognizin citicoline. It is the form used in the 2015 Richie dose-response trial and the immune-function studies that followed. Setria is not magic - it is the same molecule as any other reduced glutathione - but it is the form with published clinical PK and functional data, and it carries FDA NDI status. Most credible oral glutathione products use Setria; look for the logo on the label.
Does oral glutathione lighten skin?
Marketing says yes; the evidence says probably a little, maybe, in some people, with effect sizes that are usually small. The strongest melanin-reduction signals are from intravenous glutathione, which is outside the supplement category and has documented safety issues. Oral GSH trials in skin lightening are mostly small (n=30-60), short (4-12 weeks), conducted in Asian populations, often industry-funded, and use varying melanin assessment methods. The FDA does not permit skin lightening claims on supplements, and we will not make any here. If skin tone is your primary goal, you are unlikely to be satisfied with what oral glutathione delivers.
How long does it take for oral glutathione to work?
Months, not days. Richie 2015 reported significant rises in blood GSH by 1 month at 1000mg/day, with the full ~30-35% effect by 6 months. Levels returned to baseline within a month of stopping. If a brand promises a noticeable effect in a week or two, treat that as marketing, not pharmacology. For the immune-function endpoint (NK cytotoxicity) the same trial showed effects by 3 months.
Is S-acetyl glutathione actually better than regular glutathione?
Mechanistically reasonable, clinically unproven. The acetylation is supposed to slow GI hydrolysis. There is some in vitro and animal work supporting that, but human RCT data on S-acetyl GSH is essentially absent at the time of writing. If you see strong claims that S-acetyl is the most bioavailable form, they are based on theory rather than human trials. Setria (regular reduced GSH at a high enough oral dose) has more actual outcome data than S-acetyl does.
Can I take glutathione long-term?
The Richie 2015 trial ran 6 months at up to 1000mg/day with no serious adverse events, and decades of clinical use as an adjunct in Japan and Italy support a benign safety profile at these doses. Long-term safety at supraphysiologic doses (over 1000mg/day) is less well characterized. If you take it longer than 6 months without measurable benefit (energy, skin, lab GSH), it is reasonable to stop and consider whether NAC would have been the better target.
Sources
- Richie JP Jr, Nichenametla S, Neidig W, et al. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione. Eur J Nutr. 2015;54(2):251-263.
- Allen J, Bradley RD. Effects of oral glutathione supplementation on systemic oxidative stress biomarkers in human volunteers. J Altern Complement Med. 2011;17(9):827-833.
- Witschi A, Reddy S, Stofer B, Lauterburg BH. The systemic availability of oral glutathione. Eur J Clin Pharmacol. 1992;43(6):667-669. (Classic study showing free oral GSH is largely hydrolyzed in the GI tract - the bioavailability problem.)
- Hauser RA, Lyons KE, McClain T, Carter S, Perlmutter D. Randomized, double-blind, pilot evaluation of intravenous glutathione in Parkinson's disease. Mov Disord. 2009;24(7):979-983. (IV glutathione, not oral - cited to clarify that the Parkinson's signal in the popular literature comes from IV trials.)
- Honda Y, Kessoku T, Sumida Y, et al. Efficacy of glutathione for the treatment of nonalcoholic fatty liver disease: an open-label, single-arm, multicenter, pilot study. BMC Gastroenterol. 2017;17(1):96. (Small open-label NAFLD trial cited above - hypothesis-generating only.)
- Sinha R, Sinha I, Calcagnotto A, et al. Oral supplementation with liposomal glutathione elicits an immune response against latent reservoir of HIV-1 in cultured CD4+ lymphocytes. (Sinha-Richie lab follow-up work on Setria and liposomal GSH immune endpoints; see also subsequent papers from the same group.)
- Park EY, Shimura N, Konishi T, et al. Increase in the protein-bound form of glutathione in human blood after the oral administration of glutathione. J Agric Food Chem. 2014;62(26):6183-6189.
- Schmitt B, Vicenzi M, Garrel C, Denis FM. Effects of N-acetylcysteine, oral glutathione (GSH) and a novel sublingual GSH formulation on oxidative stress markers in healthy volunteers. Redox Biol. 2015;6:198-205.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products discussed on this page are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before starting any supplement regimen.