GlyNAC: the Kumar and Sekhar trials, with critiques
Glycine plus NAC raised glutathione in small trials from one lab. Interesting, unreplicated.
Education only, not medical advice. Talk to your clinician before starting a supplement, especially if you are pregnant, take medication or have a condition.
Evidence grade: D (A strong, B good with gaps, C limited or mixed, D early)
The studies
Sekhar's group reported that glycine and cysteine restored glutathione synthesis in people with uncontrolled diabetes over two weeks [1]. An open-label pilot in eight older adults reported improvements in glutathione, oxidative stress, mitochondrial markers, strength and gait after 24 weeks of GlyNAC [2]. A placebo-controlled trial then randomized 24 older adults to GlyNAC or alanine for 16 weeks and reported improvements in many of the same markers and in gait speed and strength [3].
Critiques
All three come from the same research group, with 12 people per arm at most [3]. The pilot had no control group [2]. Dozens of outcomes were measured, which raises the chance of false positives, and most are surrogate markers rather than health outcomes. No independent replication had been published when we reviewed. We grade GlyNAC D and do not sell it.
Sources
- Sekhar et al. 2010, Diabetes Care. doi.org/10.2337/dc10-1006
- Kumar et al. 2021, Clin Transl Med. doi.org/10.1002/ctm2.372
- Kumar et al. 2022, J Gerontol A. doi.org/10.1093/gerona/glac135
DOIs verified against Crossref and official pages checked on 2026-10-15.