Glutathione Benefits: What the Research Shows

Glutathione is a popular supplement ingredient in Malaysia. It is sold for antioxidant support, skin and liver health. But which benefits of glutathione are backed by human studies, and which are not yet proven? This guide summarises the research for formulators and brand owners. A short summary in Bahasa Melayu follows at the end.

Glutathione is an antioxidant made by every cell

Glutathione is an antioxidant and a tripeptide, a small protein made of three amino acids: glutamic acid, cysteine and glycine. Every cell can make glutathione. It is often called the master antioxidant, and it is the most abundant antioxidant the body produces itself. [1]

The active form is reduced glutathione (GSH), also sold as L-glutathione. When it neutralises a free radical, two molecules join to form oxidised glutathione (GSSG). Enzymes then recycle GSSG back to GSH.

The role of glutathione in the body

• Antioxidant defence. Glutathione neutralises free radicals and peroxides, which limits oxidative stress in cells.
• Detoxification. In the liver, glutathione binds toxins and drug metabolites so the body can clear them.
• Immune function. In one trial, oral glutathione raised natural killer cell activity. [1]
• Recycling other antioxidants. Glutathione works alongside vitamin C and vitamin E in the cell’s antioxidant network.

Oxidative stress and inflammation often occur together. That is why glutathione levels are studied in many health conditions.

Does glutathione supplementation raise glutathione levels?

This is the key question for oral glutathione, because glutathione is a peptide and the gut breaks peptides down. The trials disagree, so here are both sides.

• In a 6-month double-blind trial in 54 healthy adults, 250 or 1,000 mg a day raised glutathione in blood. At the higher dose, levels rose 30–35% in red blood cells, plasma and lymphocytes. They returned to baseline a month after stopping. [1]
• A 4-week double-blind trial in 40 healthy adults found no change in glutathione status or oxidative stress markers with 500 mg twice a day. [2]

The trials differed in length (4 weeks versus 6 months), which may explain part of the difference. Formulators exploring absorption often look at liposomal and sublingual forms. Our glutathione forms guide compares them.

Effect of glutathione on skin health

In Asia, glutathione is commonly used as a supplement to lighten skin colour. [4] Oral glutathione has been tested in several placebo-controlled trials. A 2025 systematic review found that 250–500 mg a day lowered the skin melanin index versus placebo in five randomised trials. The effect did not last after people stopped. [3] An earlier review called the evidence inconclusive because of study quality and mixed results. [4]

Our glutathione for skin guide covers the oral and topical studies in detail.

Glutathione and liver disease

Glutathione has been given by injection for chronic liver disease. [5] Whether oral glutathione may help the liver is less clear. In an open-label pilot study, 29 people with non-alcoholic fatty liver disease completed 4 months of 300 mg a day. Their ALT liver enzyme levels fell, as did triglycerides. [5] The study had no placebo group, and the authors called for larger trials.

How to increase glutathione levels

The body builds glutathione from its three amino acids. Cysteine is usually considered the limiting one. That is why N-acetyl cysteine (NAC), a cysteine source, is widely used as a glutathione precursor. In a small crossover trial in 20 people with metabolic syndrome, a sublingual glutathione raised plasma glutathione more than standard oral glutathione or NAC. [6] Two of the authors worked for the company that makes the sublingual product.

What happens if I take glutathione every day?

In the trials above, people were taking glutathione supplements daily for 4 weeks to 6 months. Blood levels rose with daily use and fell back within a month of stopping. [1] Skin effects also faded after stopping. [3] So the benefits studied so far depend on continued use.

Side effects of glutathione

Skin trials of oral glutathione reported it was well tolerated, as our safety guide explains. IV glutathione is another matter: a 2025 review concluded it is contraindicated because of a lack of efficacy and side effects. [3] See our full guide to glutathione side effects and safety.

Glutathione or collagen?

They do different jobs. Glutathione is a three-amino-acid antioxidant. Collagen is a large structural protein, sold as peptides for skin and joints. Beauty supplements often combine glutathione with vitamin C rather than with collagen alone.

Ringkasan dalam Bahasa Melayu: glutathione untuk apa?

Glutathione ialah antioksidan semula jadi yang dihasilkan oleh sel badan daripada tiga asid amino: asid glutamik, sisteina dan glisina. Ia melindungi sel daripada tekanan oksidatif dan membantu hati menyingkirkan toksin.

Kebaikan glutathione yang dikaji pada manusia:

• Pengambilan 250–1,000 mg sehari selama 6 bulan meningkatkan paras glutathione dalam darah. [1]
• Pengambilan 250–500 mg sehari menurunkan indeks melanin kulit berbanding plasebo, tetapi kesannya hilang selepas berhenti. [3]
• Glutathione melalui suntikan IV tidak disyorkan kerana kurang berkesan dan mempunyai kesan sampingan. [3]

Untuk pengeluar suplemen, FC Materials membekalkan L-glutathione reduced dengan COA untuk setiap batch.

What the research says

• In a 6-month double-blind trial in 54 healthy adults, oral glutathione at 250 or 1,000 mg a day raised blood glutathione, by 30–35% in several blood compartments at the higher dose. Levels returned to baseline a month after stopping. [1]
• In a 4-week double-blind trial in 40 healthy adults, 500 mg twice a day did not change glutathione status or oxidative stress markers. [2]
• A 2025 systematic review found oral glutathione at 250–500 mg a day lowered the melanin index versus placebo in five randomised trials, with no lasting effect after stopping. It concluded IV glutathione is contraindicated. [3]
• In an open-label pilot study without a placebo group, 300 mg a day for 4 months lowered ALT in 29 people with non-alcoholic fatty liver disease. [5]

These summaries describe published research on the ingredient. They are not claims for any finished product; claims on finished products must meet the rules of the market where they are sold.

References

1. Richie JP, et al. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione. Eur J Nutr. 2015;54(2):251-263. doi:10.1007/s00394-014-0706-z
2. 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. doi:10.1089/acm.2010.0716
3. Sarkar R, et al. Glutathione as a skin-lightening agent and in melasma: a systematic review. Int J Dermatol. 2025;64(6):992-1004. doi:10.1111/ijd.17535
4. Dilokthornsakul W, et al. The clinical effect of glutathione on skin color and other related skin conditions: a systematic review. J Cosmet Dermatol. 2019;18(3):728-737. doi:10.1111/jocd.12910
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. doi:10.1186/s12876-017-0652-3
6. Schmitt B, et al. Effects of N-acetylcysteine, oral glutathione (GSH) and a novel sublingual form of GSH on oxidative stress markers: a comparative crossover study. Redox Biol. 2015;6:198-205. doi:10.1016/j.redox.2015.07.012