A 2023 Baylor University trial found GlyNAC supplementation (glycine + N-acetylcysteine) reversed multiple aging hallmarks in healthy older adults. It's the most comprehensive clinical trial evidence for any single supplement combination in longevity history.
A 2023 randomized controlled trial published in *The Journal of Nutrition* by Premranjan Kumar and colleagues at Baylor College of Medicine produced results that were, by supplement trial standards, extraordinary. GlyNAC — a combination of glycine and N-acetylcysteine — supplemented for 24 weeks in healthy older adults reversed deficiencies in multiple aging hallmarks simultaneously. The trial measured outcomes that almost no supplement study has touched: mitochondrial function, oxidative stress, inflammation, insulin resistance, cognitive function, and muscle strength — and found significant improvements across all of them.
Here is what GlyNAC is, what the trial found, and what the evidence means for practical supplementation.
Glutathione (GSH) is the body's master antioxidant. Unlike vitamin C or E, which are dietary antioxidants, glutathione is synthesized endogenously. It neutralizes reactive oxygen species (ROS), regenerates other antioxidants, supports mitochondrial function, and plays roles in detoxification, immune function, and DNA repair.
Glutathione levels fall ~30–50% with aging. Kumar's group identified this glutathione deficiency as a consequence of substrate deficiency: aging cells don't lack glutathione-synthesizing enzymes — they lack adequate concentrations of glycine and cysteine, the two amino acids from which glutathione is made.
The two key amino acid precursors: