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.

Last reviewed: June 22, 2026

This definition is educational and is not medical advice, a diagnosis, or treatment. Talk to a doctor about any health decisions. Read our full medical disclaimer