# GlyNAC (Glycine + N-acetylcysteine)

GlyNAC is the combined supplement of glycine plus N-acetylcysteine (NAC). The aim is to refill both building blocks of glutathione (the tripeptide γ-Glu-Cys-Gly), which falls steadily as you age. It works by supplying the two limiting precursors at once: cysteine (via NAC) and glycine. (The middle step, gamma-glutamylcysteine, is usually less of a bottleneck in older adults.) Rajagopal Sekhar and colleagues at Baylor College of Medicine pioneered it. They ran randomized, double-blind pilot trials in older adults. (These GlyNAC trials, published 2021 to 2024, had about 8 to 24 people per arm and used 16 to 24 weeks of supplements.) They reported two main findings. Red-cell glutathione was restored toward young-adult levels. And many aging domains improved: mitochondrial fuel use, oxidative stress, inflammation, blood-vessel function, insulin resistance, DNA damage, muscle strength, and walking speed. But independent replication and longer outcome trials are missing. The evidence so far is short-duration trials with small samples. GlyNAC is sold as a dietary supplement and has no approved medical use.

## Sources

- Kumar P, Liu C, Suliburk J, et al.. (2021). Glycine and N-acetylcysteine (GlyNAC) supplementation in older adults improves glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, insulin resistance, endothelial dysfunction, genotoxicity, muscle strength, and cognition: Results of a pilot clinical trial. Clinical and Translational Medicine. https://doi.org/10.1002/ctm2.372
- Kumar P, Liu C, Hsu JW, et al.. (2023). Supplementing Glycine and N-Acetylcysteine (GlyNAC) in Older Adults Improves Glutathione Deficiency, Oxidative Stress, Mitochondrial Dysfunction, Inflammation, Physical Function, and Aging Hallmarks: A Randomized Clinical Trial. Journals of Gerontology Series A. https://doi.org/10.1093/gerona/glac135

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_Canonical: https://longevity-switzerland.com/en/glossary/glynac · Part of Longevity Cities · Updated 2026-06-22_