Randomized controlled trial of oral glutathione supplementation on body stores of glutathione

Whether oral glutathione can meaningfully raise body stores has been a longstanding debate in clinical nutrition. This randomized, double-blind, placebo-controlled trial by Richie, Nichenametla, Neidig, and colleagues, published in the European Journal of Nutrition, provided definitive evidence that it can.

The researchers enrolled 54 healthy adults and randomized them to receive either 250 mg/day or 1,000 mg/day of oral glutathione, or placebo, for 6 months. They measured GSH levels in erythrocytes, plasma, lymphocytes, and buccal cells at baseline, 1, 3, and 6 months, as well as immune function markers including natural killer cell cytotoxicity.

The high-dose group (1,000 mg/day) showed impressive results: erythrocyte GSH increased 30-35%, plasma GSH rose significantly, and buccal cell levels jumped by 260%. Most notably, NK cell cytotoxicity more than doubled compared to placebo at the 3-month mark. All effects were dose-dependent, with the 250 mg group showing more modest improvements. After a 1-month washout period, levels returned to baseline.

This trial settled the debate about oral glutathione bioavailability. The dose-dependent increases across multiple tissue compartments, combined with the dramatic improvement in immune function, establish oral glutathione as a clinically meaningful intervention for raising body stores and enhancing immune defense.