Glutathione Supplement Ireland: Evidence Guide to the Master Antioxidant
Glutathione is all over social media for "glow" and "detox". Here is what the human trials actually show on absorption, skin and liver, how it compares with NAC, how much to take, and what to check before you buy in Ireland.
What it is. Glutathione (GSH) is an antioxidant the body makes from three amino acids. Supplements are sold in Ireland as food supplements under FSAI rules, not medicines, and no EU health claim is authorised for glutathione.
What the evidence shows. Oral glutathione can raise blood glutathione: a 6-month randomised trial in 54 adults found 30 to 35% higher levels at 1,000 mg a day versus placebo (Richie et al., Eur J Nutr, 2015, PMID 24791752). Skin whitening is not established: a 2019 systematic review called the evidence "inconclusive".
What to buy. Reduced glutathione is the best-studied form. Probiotic.ie stocks NOW Foods Glutathione 500mg (30, 60 or 120 vegan capsules), and NAC as the alternative route, shipped from Dublin with no customs charges.
Glutathione (GSH, L-glutathione) definition: glutathione is a tripeptide made in the body from cysteine, glycine and glutamic acid, present in almost every cell, and sold as a supplement mainly in its reduced form in 250 to 500 mg capsules.
- What it is: a tripeptide antioxidant (cysteine + glycine + glutamic acid)
- Made by the body? Yes, in almost every cell
- Supplement forms: reduced (GSH), liposomal, S-acetyl; NAC is an indirect route
- Trial doses: 250 to 1,000 mg a day (Richie et al., 2015)
- Is it a stimulant? No
- Skin whitening? Not established; no EU health claim
- EU health claim for glutathione: none authorised
- Vegan? NOW Foods Glutathione 500mg uses a vegetable capsule
- Irish regulatory status: food supplement under FSAI rules, not a medicine
- Irish VAT on supplements: 13.5%
- Glutathione is not a medicine and is not sold to treat, prevent or cure any condition.
- Glutathione is not proven to whiten or lighten skin.
- Glutathione is not proven to "detox" the liver in healthy adults.
- Oral glutathione is not the same as IV glutathione, which carries different risks and is not a food supplement.
- Raised blood glutathione is a measurement, not proof of a health benefit.
What is well-supported: oral glutathione raised blood glutathione versus placebo over 6 months (Richie et al., Eur J Nutr, 2015, PMID 24791752).
What is not proven: skin whitening, liver "detox" or any health outcome in healthy adults from supplementing.
Human dose range in trials: 250 to 1,000 mg a day.
Key safety note: speak to a GP or pharmacist first if pregnant, breastfeeding, on medication or having medical treatment.
The research discussed in this article relates to glutathione as a studied compound. It should not be read as a claim that NOW Foods Glutathione 500mg, or any other product sold by Probiotic.ie, produces these effects. These products are food supplements, not medicines. No authorised EU health claim is made for glutathione on this page or on any product.
NOW Foods Glutathione 500mg, Vegan Capsules
500 mg reduced glutathione per capsule, with 100 mg milk thistle extract and 50 mg alpha lipoic acid. One capsule a day. Choose 30, 60 or 120 capsules.
Current price on the product page, including Irish VAT at 13.5%. Food supplement, not a medicine. No customs charges. Free DPD delivery on Republic of Ireland orders over €75.
What is glutathione? The antioxidant explained
Glutathione is a short chain of three amino acids: cysteine, glycine and glutamic acid. The body makes it in almost every cell, with high levels in the liver.
It is often called the "master antioxidant". That is a popular nickname, not a regulatory or medical term.
Donates electrons to reactive oxygen species.
Evidence: established biochemistryLinked with vitamin C and E recycling in cells.
Evidence: established biochemistryBinds some compounds so the body can clear them.
Evidence: biochemistry; supplement outcomes not shownCysteine supply limits how much the body makes.
Evidence: established biochemistrySmall studies suggest older adults can have lower glutathione than younger adults; one 2011 study compared 8 older and 8 younger people (Sekhar et al., Am J Clin Nutr, 2011, PMID 21795440).[1]
Does oral glutathione work? The bioavailability evidence
For years the assumption was that oral glutathione is broken down in the gut before it can be absorbed. A 6-month trial challenged that.
Richie et al.: 6 months, 54 adults
Healthy adults took 250 mg or 1,000 mg of oral glutathione a day, or placebo. At 6 months the higher dose showed 30 to 35% higher glutathione in red blood cells, plasma and lymphocytes. Levels returned towards baseline after stopping.[2]
Richie JP Jr et al. Eur J Nutr. 2015;54(2):251-263. PMID 24791752.
Blood levels are not outcomes
The trial measured glutathione levels, not health outcomes. It used a branded fermented glutathione (Setria) and was funded by its manufacturer. Results may not apply equally to every product.
Glutathione for skin: what the evidence actually shows
Skin "glow" is the main reason glutathione trends online. The trials are small and the results are weaker than social media suggests.
Weschawalit et al.: 12 weeks, 60 women
Thai women aged 20 to 50 took 250 mg glutathione (GSH), 250 mg oxidised glutathione (GSSG) or placebo. Melanin differences versus placebo were not significant overall. In women over 40, GSH was lower than placebo at one sun-exposed site, and some wrinkle measures improved.[3]
Weschawalit S et al. Clin Cosmet Investig Dermatol. 2017;10:147-153. PMID 28490897.
Dilokthornsakul et al.: "inconclusive"
A review of four trials concluded the evidence for a skin whitening effect of glutathione is still inconclusive, with a possible trend in sun-exposed areas only.[4]
Dilokthornsakul W et al. J Cosmet Dermatol. 2019;18(3):728-737. PMID 30895708.
- Trials were small and mostly in Asian populations with darker skin types than most Irish skin.
- No EU health claim exists for glutathione and skin, so no product can lawfully promise skin results.
- Realistic expectation: no reliable visible skin change has been shown.
Glutathione and liver support
Glutathione is central to liver biochemistry. That does not mean a supplement protects or "detoxes" a healthy liver.
Honda et al.: 29 patients
People with fatty liver disease took 300 mg glutathione a day for 4 months in an open-label pilot. Liver enzyme ALT fell. There was no control group, and this was a clinical population, not healthy adults.[5]
Honda Y et al. BMC Gastroenterol. 2017;17(1):96. PMC5549431.
"Detox" is not shown
No controlled trial in healthy adults shows a glutathione supplement "cleanses" or "detoxes" the liver. In hospital, paracetamol overdose is treated with acetylcysteine (NAC), not glutathione supplements.
Forms of glutathione: reduced, liposomal, S-acetyl, NAC
| Form | How it works | Human evidence |
|---|---|---|
| Reduced glutathione (GSH) | Supplies the active form directly | Best studied (Richie 2015) |
| Liposomal glutathione | Wrapped in fat particles to protect it from digestion | No head-to-head trial vs reduced |
| S-acetyl glutathione | Chemically protected form | Little comparative human data |
| NAC | Supplies cysteine so the body makes its own | Large body of human research |
NOW Foods Glutathione 500mg contains reduced glutathione, the same form studied by Richie et al. NOW does not state that it uses the branded Setria ingredient used in that trial.
Glutathione vs NAC: which should I buy?
Both relate to the same antioxidant system, but they take different routes. Our NAC supplement Ireland guide covers NAC in full.
| Feature | NOW Foods Glutathione 500mg | NOW Foods NAC 600mg |
|---|---|---|
| Route | Supplies glutathione directly | Supplies cysteine; body makes glutathione |
| Per capsule | 500 mg reduced glutathione, 100 mg milk thistle extract, 50 mg alpha lipoic acid | 600 mg NAC, 25 mcg selenium, 50 mcg molybdenum |
| Label serving | 1 capsule daily, empty stomach | 1 capsule once or twice daily |
| Packs | 30, 60 or 120 capsules | 100 capsules |
| Human evidence | Raises blood GSH (one 6-month RCT) | Larger, longer research base |
| Vegan | Yes | Yes |
- Want glutathione itself, one capsule a day? NOW Foods Glutathione 500mg.
- Want the more-researched route? NOW Foods NAC 600mg. It also contains selenium, and selenium contributes to the protection of cells from oxidative stress.
The selenium statement is an authorised EU health claim for selenium (25 mcg, 45% NRV per NAC capsule), not a claim for NAC or glutathione. No claim is made for the milk thistle or alpha lipoic acid in the glutathione product.
Dosage, timing, and how long to take it
- Trial doses: 250 to 1,000 mg a day.[2]
- NOW label: 1 capsule (500 mg) daily, preferably on an empty stomach.
- How long: in the Richie trial, blood levels were higher than placebo from 1 month and stayed higher at 6 months.
- After stopping: blood levels went back towards baseline.
- Days per pack at 1 a day: 30, 60 or 120 days.
Side effects, safety, and drug interactions
- Well tolerated at 250 to 1,000 mg a day for 6 months in the Richie trial.
- Mild digestive effects are occasionally reported.
- IV glutathione is different. It is given by injection, carries different risks, and is not a food supplement.
- are pregnant or breastfeeding
- take prescription medication
- are having cancer treatment or other medical treatment
- have kidney or liver disease
Glutathione supplements in Ireland
- Legal to buy. Glutathione is sold in Ireland as a food supplement under FSAI rules and the EU Food Supplements Directive 2002/46/EC.[6] It is not a medicine.
- No authorised health claim. No EU health claim is authorised for glutathione under Regulation (EC) No 1924/2006, so no product can lawfully claim skin, liver or immune benefits.
- FSAI notification is not approval. The FSAI states notification is not an approval or authorisation process.[7]
- 13.5% VAT. Food supplements carry Ireland's reduced VAT rate.[8]
- No customs from us. Stock ships from Dublin. Orders from outside the EU can attract VAT and customs charges (see customs charges Ireland).
Product details were checked by Probiotic.ie on 14 October 2026 against the NOW Foods manufacturer listing and the live Probiotic.ie product pages: NOW Foods Glutathione 500mg (500 mg reduced glutathione, 100 mg milk thistle extract standardised to 80 mg silymarin, 50 mg alpha lipoic acid per vegetable capsule; 30, 60 or 120 capsules; 1 capsule daily, preferably on an empty stomach) and NOW Foods NAC 600mg (600 mg NAC, 25 mcg selenium, 50 mcg molybdenum per vegan capsule). Always check the label on the pack you receive.
The research discussed in this article relates to glutathione and NAC as studied compounds and should not be read as a claim that any product sold by Probiotic.ie produces these effects. These products are food supplements, not medicines. The only authorised health claim on this page is for selenium, at the stated amount in NOW Foods NAC 600mg.
Ready to order? NOW Foods Glutathione 500mg
Reduced glutathione, one vegan capsule a day. Or choose NAC 600mg to support your own production.
Current price on the product page, including Irish VAT at 13.5%. Food supplement, not a medicine. Prefer NAC? View NOW Foods NAC 600mg.
Frequently asked questions
What is glutathione and what does it do?
Glutathione (GSH) is a tripeptide made by the body from three amino acids: cysteine, glycine and glutamic acid. It is found in almost every cell and acts as an antioxidant, neutralising reactive oxygen species and helping recycle other antioxidants. The body makes its own glutathione; supplements supply it from outside. No EU health claim is authorised for glutathione.
Does oral glutathione actually work? Is it absorbed?
Oral glutathione can raise glutathione levels in the blood. In a 6-month randomised controlled trial in 54 healthy adults, Richie et al. found 1,000 mg a day raised glutathione in red blood cells, plasma and lymphocytes by 30 to 35% compared with placebo (Eur J Nutr, 2015, PMID 24791752). The trial measured blood levels, not health outcomes, and used a branded fermented glutathione.
Does glutathione whiten skin or reduce pigmentation?
This is not established. A 2019 systematic review of four trials by Dilokthornsakul et al. concluded the evidence for a skin whitening effect of glutathione is still inconclusive (J Cosmet Dermatol, 2019, PMID 30895708). In a 12-week trial in 60 Thai women, melanin differences versus placebo were not significant overall (Weschawalit et al., 2017). No EU health claim exists for glutathione and skin.
Should I take NAC or glutathione?
They take different routes to the same system. Glutathione supplies the finished molecule; NAC (N-acetylcysteine) supplies cysteine, which the body uses to make its own glutathione. NAC has the larger body of human research; oral glutathione has direct evidence of raising blood glutathione levels. Our NAC supplement Ireland guide covers NAC in detail.
What is the best form of glutathione supplement?
Reduced glutathione (GSH) has the most human trial data, including the 6-month Richie et al. trial. Liposomal glutathione is designed to improve absorption, but no head-to-head trial has shown it works better than reduced glutathione at the same dose. S-acetyl glutathione has little comparative human data. Choose a product that states the form and the amount per capsule.
Is glutathione good for the liver?
Glutathione is central to liver biochemistry, but that does not mean a supplement protects a healthy liver. The main human study is a small open-label pilot in 29 people with fatty liver disease, with no control group (Honda et al., BMC Gastroenterol, 2017). Claims that glutathione supplements "detox" the liver are not supported by controlled trials in healthy adults.
How much glutathione should I take per day?
Follow the product label. Human trials have used 250 mg to 1,000 mg a day (Richie et al.). NOW Foods Glutathione 500mg suggests 1 capsule daily, preferably on an empty stomach. There is no official recommended intake for glutathione.
How long does glutathione take to work?
In the Richie et al. trial, blood glutathione was higher than placebo at 1 month, and the increase continued at 3 and 6 months. Levels returned towards baseline after stopping (Eur J Nutr, 2015). Blood levels are a measurement, not a guarantee of any felt effect.
What are the side effects of glutathione supplements?
In the 6-month Richie et al. trial, oral glutathione was well tolerated. Mild digestive effects are occasionally reported. Intravenous glutathione is a different thing with different risks and is not a food supplement. If you are pregnant, breastfeeding, taking medication or having medical treatment, speak to your GP or pharmacist first.
Is glutathione legal in Ireland?
Yes. Glutathione is sold legally in Ireland as a food supplement under FSAI food supplement rules (FSAI). No prescription is needed and it is not a medicine. No EU health claim is authorised for glutathione under Regulation (EC) No 1924/2006. Food supplements carry Irish VAT at 13.5% (Revenue).
Can I take glutathione with vitamin C?
Yes, there is no known reason not to take them together, and many people do. Vitamin C and glutathione are linked in the body's antioxidant recycling. There is little trial evidence that taking them together produces a better result than either alone.
Where can I buy glutathione supplements in Ireland?
Glutathione is sold in Irish pharmacies, health food shops and online. Probiotic.ie stocks NOW Foods Glutathione 500mg in 30, 60 and 120 vegan capsule packs, shipped from Dublin with no customs charges and free DPD delivery on Republic of Ireland orders over €75 (delivery information).
- Glutathione (GSH) is an antioxidant tripeptide the body makes from cysteine, glycine and glutamic acid.
- No EU health claim is authorised for glutathione under Regulation (EC) No 1924/2006.
- Oral glutathione at 1,000 mg a day raised blood glutathione by 30 to 35% versus placebo over 6 months in 54 adults (Richie et al., Eur J Nutr, 2015, PMID 24791752).
- A 2019 systematic review called the evidence for glutathione skin whitening "inconclusive" (Dilokthornsakul et al., J Cosmet Dermatol, PMID 30895708).
- No controlled trial shows glutathione supplements "detox" a healthy liver.
- NAC is an indirect route: it supplies cysteine so the body makes its own glutathione.
- In Ireland, glutathione is sold as a food supplement under FSAI rules, not a medicine; 13.5% VAT applies.
- Probiotic.ie stocks NOW Foods Glutathione 500mg (30, 60 or 120 vegan capsules) and NOW Foods NAC 600mg, shipped from Dublin with no customs charges.
More evidence guides from Probiotic.ie
This guide was first published on 28 May 2026 and reviewed by Probiotic.ie on 14 October 2026. In the review we:
- Re-checked every citation against PubMed or publisher records, and corrected a misattributed skin review, an overstated skin trial result, an unsupported age-decline statistic and a wrong PMC record from the original version.
- Reviewed Richie 2015, Weschawalit 2017, Dilokthornsakul 2019, Honda 2017 and Sekhar 2011.
- Separated hospital and IV uses from food supplement use throughout.
- Checked FSAI food supplement rules and confirmed no EU health claim is authorised for glutathione.
- Verified product details against the NOW Foods listing and our live product pages.
- Made no disease-treatment claims and no health claims for glutathione.
This guide has not been reviewed by a clinician. It is not medical advice.
Sources
- [1] Sekhar RV et al. Deficient synthesis of glutathione underlies oxidative stress in aging and can be corrected by dietary cysteine and glycine supplementation. Am J Clin Nutr. 2011;94(3):847-853. PMID 21795440. — pubmed.ncbi.nlm.nih.gov/21795440
- [2] Richie JP Jr et al. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione. Eur J Nutr. 2015;54(2):251-263. PMID 24791752. — pubmed.ncbi.nlm.nih.gov/24791752
- [3] Weschawalit S, Thongthip S, Phutrakool P, Asawanonda P. Glutathione and its antiaging and antimelanogenic effects. Clin Cosmet Investig Dermatol. 2017;10:147-153. PMID 28490897. — pubmed.ncbi.nlm.nih.gov/28490897
- [4] Dilokthornsakul W, Dhippayom T, Dilokthornsakul P. The clinical effect of glutathione on skin color and other related skin conditions: a systematic review. J Cosmet Dermatol. 2019;18(3):728-737. PMID 30895708. — pubmed.ncbi.nlm.nih.gov/30895708
- [5] Honda 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. PMC5549431. — pmc.ncbi.nlm.nih.gov/articles/PMC5549431
- [6] Food Safety Authority of Ireland. Food Supplements: legislation and guidance. — fsai.ie/legislation/food-legislation/food-supplements
- [7] Food Safety Authority of Ireland. Food Supplements – Legislative Requirements. 2024. — fsai.ie (PDF)
- [8] Revenue Commissioners. Tax and Duty Manual: VAT treatment of food supplement products. — revenue.ie (PDF)