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

This randomized, double-blind, placebo-controlled clinical trial evaluated the efficacy of oral glutathione (GSH) supplementation in increasing body stores of this essential antioxidant. The study included 54 healthy adults randomized to receive glutathione at doses of 250 mg/day or 1000 mg/day, or placebo, for 6 months.

The results demonstrated that the high dose of glutathione (1000 mg/day) produced significant increases in GSH levels across multiple biological compartments:

• Erythrocytes: 30-35% increase in GSH levels
• Plasma: significant elevation of GSH concentrations
• Lymphocytes: substantial increase in intracellular stores
• Even the low dose (250 mg) produced measurable elevations, though less pronounced

A particularly notable finding was the effect on immune function: Natural Killer (NK) cell cytotoxicity increased more than two-fold in the high-dose group compared to placebo. NK cells are crucial components of innate immunity, responsible for eliminating virus-infected cells and tumor cells.

This study was important for challenging the prevailing view that oral glutathione would be ineffective due to degradation in the gastrointestinal tract. The data clearly demonstrated that oral supplementation at adequate doses can significantly elevate body GSH stores and enhance immune function, establishing an evidence base for the clinical use of oral glutathione.