Glycine vs Taurine
Two cheap amino acids, each carrying an animal lifespan result and a human story that does not follow from it. The limits are different, and they matter.
Glycine
Aminoacetic acid, Gly
A genuine 4–6% lifespan result in the ITP and Mendelian-randomisation support for lower coronary risk — but the human sleep evidence comes from a single corporate lab and there is no collagen outcome trial at all.
Full Glycine evidence reviewTaurine
Reversed aging markers and extended lifespan in animals (Singh 2023), with a human association — but no human outcome trial yet.
Full Taurine evidence reviewSide by side
| Glycine | Taurine | |
|---|---|---|
| Marketed for | Sleep quality, collagen support, glutathione, healthy aging | Longevity, healthspan |
| Evidence grade | Clinical data | Preclinical / minimal |
| Family | mTOR & other | mTOR & other |
| Key human source | ITP lifespan study, Aging Cell 2019 | Animal + association, Science 2023 |
marks a row where the two differ. Evidence grades come from our evidence matrix, which grades each molecule on the human data for the use it is marketed for.
Our verdict
Both have a real rodent lifespan finding and neither has a human outcome trial, so the honest comparison is what each result actually rests on. Glycine's is the sturdier kind: in the NIA Interventions Testing Program an 8% glycine diet extended median lifespan 4–6% in both male and female mice at all three sites — replicated across sites, at an intake roughly twenty times a human bedtime dose per kilogram. Taurine's comes from the 2023 Singh work in Science, where taurine declined with age across species and supplementation extended lifespan and healthspan markers in mice, but a 2025 analysis of longitudinal human and primate data found circulating taurine does not reliably decline with age in people, which undercuts the restore-what-you-lost premise rather than the mouse result itself. Neither borrows well from the other: glycine's human sleep evidence is small crossover work from a single corporate laboratory with no independent replication and no meta-analysis to pool, and taurine's human trials are modest cardiometabolic ones — lower blood pressure and improved vascular function in prehypertension, with cognitive effects rated limited and inconclusive.
Glycine fits if
Glycine is the more defensible cheap experiment for someone targeting sleep onset or covering a plausible dietary shortfall, on the understanding that the collagen claim has no human outcome trial behind it at all.
Taurine fits if
Taurine suits someone focused on blood pressure and vascular measures, where the small randomised signal is real, and who reads the anti-aging framing as mouse data resting on a human premise that failed to replicate.