Randomized controlled trial of oral glutathione supplementation on body stores of glutathione.
Level 2 - randomized trial
Randomized, double-blind, placebo-controlled trial
PubMed 24791752 · doi:10.1007/s00394-014-0706-z
What was done
A 6-month randomized, double-blind, placebo-controlled trial evaluated oral glutathione (GSH) supplementation at 250 mg/day or 1,000 mg/day versus placebo in 54 healthy, non-smoking adults. GSH concentrations were measured in whole blood, erythrocytes, plasma, lymphocytes, and exfoliated buccal mucosal cells at baseline, 1, 3, and 6 months, followed by a 1-month washout period. A subset of participants was assessed for secondary immune markers, including natural killer cell cytotoxicity.
What was found
Blood GSH levels increased at 1, 3, and 6 months versus baseline in both dose groups (P < 0.05). At 6 months in the 1,000 mg/day group, mean GSH levels increased 30-35% in erythrocytes, plasma, and lymphocytes, and 260% in buccal cells (P < 0.05). In the 250 mg/day group, GSH increased 17% in blood and 29% in erythrocytes at 6 months (P < 0.05). Increases were dose- and time-dependent, returning to baseline after 1-month washout. The oxidized-to-reduced glutathione ratio in whole blood decreased in both dose groups at 6 months. Natural killer cytotoxicity increased >twofold in the 1,000 mg/day group versus placebo at 3 months (P < 0.05).
Why it matters
This study provides evidence that oral glutathione is bioavailable in humans and can augment body stores across multiple tissue compartments, challenging previous assumptions that oral intake does not alter systemic levels.
Limits
The sample size was small (54 total participants across three arms), and immune functional testing was performed only on an unspecified subset. The cohort was restricted to healthy non-smokers, so results cannot be generalized to populations with baseline glutathione depletion or clinical disease, and long-term clinical health outcomes were not evaluated.
Cited by
- contradicts Non-liposomal oral glutathione is not effectively absorbed or transported into human cells because cells lack transporters for external glutathione.