Glutathione

Neutralizes reactive oxygen species, the unstable molecules produced during normal metabolism that can damage DNA, proteins, and cell membranes when they accumulate.

Serves as a cofactor for glutathione peroxidase, the enzyme that converts hydrogen peroxide into water, preventing downstream oxidative injury.

Recycles other antioxidants like vitamin C and vitamin E back to their active forms, extending their protective action inside cells.

Maintains redox balance inside mitochondria, the energy-producing structures in cells, which is required for efficient ATP production.

In randomized trials of older adults, precursor loading with glycine and N-acetylcysteine raised intracellular glutathione, improved mitochondrial fuel burning, and reversed several aging biomarkers.

Binds to environmental toxins, heavy metals, and drug metabolites through phase II conjugation, making them water-soluble so they can be excreted through bile or urine.

Is the main defense against acetaminophen overdose, where depleted glutathione stores are the mechanism of liver injury, and N-acetylcysteine is given as a glutathione precursor to treat it.

Higher intracellular glutathione is associated with better T cell and natural killer cell function. In a pilot study, oral liposomal glutathione raised natural killer cell cytotoxicity meaningfully within two weeks.

Older adults taking 500 mg daily for four months in a randomized trial reported reduced cold and flu symptom burden and improved immune cell markers.

Intracellular glutathione levels decline with age and with chronic illness, contributing to the oxidative stress and mitochondrial dysfunction seen in older adults.

Restoring glutathione stores, directly or through precursor supplementation, is an active area of clinical research on aging-related decline.