Glutathione

Is glutathione absorbed when taken by mouth?

Updated 10 Nov 2026

Short answer

Partly. Enzymes in the gut and liver break swallowed glutathione down, and one large dose did not raise its level in the blood.[1] But in a 6-month trial, 250 or 1,000 mg a day did raise glutathione in the blood.[2] A 4-week trial of 1,000 mg a day found no rise.[3]

What one dose does

In a 1992 study, 7 healthy volunteers took one dose of glutathione of about 3 g. Before the dose, their plasma held about 6 µmol/L of glutathione. Over the next 4.5 hours, the levels of glutathione, cysteine and glutamate in their blood plasma did not rise significantly.[1] The authors explained this by an enzyme, gamma-glutamyltransferase, in the gut and the liver. It splits glutathione into its amino acids before it reaches the blood.[1]

What daily use does

A 6-month trial in 54 non-smoking adults compared 250 mg a day, 1,000 mg a day and placebo:[2]

  • Glutathione in the blood rose after 1, 3 and 6 months with both doses.[2]
  • At 6 months, 1,000 mg a day raised levels by 30% to 35% in red blood cells, plasma and lymphocytes, and by 260% in cells from the inside of the cheek.[2]
  • 250 mg a day raised levels by 17% in whole blood and by 29% in red blood cells.[2]
  • With both doses, the ratio of oxidized to reduced glutathione in the blood fell, a sign of less oxidative stress.[2]
  • 1 month after people stopped, levels were back where they started.[2]

A smaller trial gave 40 healthy adults 500 mg twice a day, or placebo, for 4 weeks. It found no change in glutathione in red blood cells and no change in two markers of oxidative damage in urine.[3]

Other forms

In a 1-month pilot study, 12 healthy adults took liposomal glutathione at 500 or 1,000 mg a day. Glutathione rose by up to 40% in whole blood and by up to 28% in plasma after 2 weeks.[4] A marker of oxidative damage in plasma, 8-isoprostane, fell by 35%.[4] A company that supplies liposomal glutathione paid for the study.[4]

In a 3-week crossover trial, 20 people with metabolic syndrome took sublingual glutathione, plain glutathione by mouth and NAC, one after another. Sublingual glutathione raised glutathione in plasma more than plain glutathione by mouth did.[5] Two of the authors worked for Laboratoires Le Stum.[5]

A 2026 review said that liposomal, nasal and sublingual forms may make glutathione more stable and more available to the body. It also said that proof of real health benefits from these forms is still limited.[6]

How the two trials compare

The trial that found no change lasted 4 weeks and measured glutathione in red blood cells.[3] The 6-month trial found higher levels in the blood already after 1 month, and in most cases the rise grew with the dose and with time.[2]

Sources (6)

  1. The systemic availability of oral glutathione. Witschi A, Reddy S, Stofer B, Lauterburg BH Eur J Clin Pharmacol, 1992. PMID 1362956
  2. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione. Richie JP Jr, Nichenametla S, Neidig W, Calcagnotto A, Haley JS, Schell TD, et al. Eur J Nutr, 2015. PMID 24791752
  3. Effects of oral glutathione supplementation on systemic oxidative stress biomarkers in human volunteers. Allen J, Bradley RD J Altern Complement Med, 2011. PMID 21875351
  4. Oral supplementation with liposomal glutathione elevates body stores of glutathione and markers of immune function. Sinha R, Sinha I, Calcagnotto A, Trushin N, Haley JS, Schell TD, et al. Eur J Clin Nutr, 2018. PMID 28853742
  5. Effects of N-acetylcysteine, oral glutathione (GSH) and a novel sublingual form of GSH on oxidative stress markers: A comparative crossover study. Schmitt B, Vicenzi M, Garrel C, Denis FM Redox Biol, 2015. PMID 26262996
  6. Glutathione in redox homeostasis: Bridging molecular mechanisms, bioavailability constraints, and translational challenges in systemic therapeutics. Carnib BL, Matos ERSB, Lage TM, Pedro IDR, Ecclissato MCD, Teixeira RL, et al. Biomed Pharmacother, 2026. PMID 42585816

More about glutathione

What is glutathione?Does glutathione work?Do glutathione levels fall with age?Is glutathione safe?Does glutathione lighten skin?Does glutathione help the liver?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.