Comparison
Creatine vs Glycine
Creatine
The most-studied performance supplement in history, now well-evidenced as a cognitive enhancer in its own right. The brain consumes about 20% of resting metabolic rate, and creatine buffers ATP at the use site for fast regeneration — especially valuable under mental fatigue and sleep deprivation. Vegetarians benefit most because dietary creatine comes from animal flesh.
Glycine
Smallest amino acid, inhibitory neurotransmitter and sleep enhancer. NMDA co-agonist.
| Field | Creatine | Glycine |
|---|---|---|
| Category | amino-acid | amino-acid |
| Dose range | 3000–5000mg | 3000–5000mg |
| Half-life | 3h | 1h |
| Onset | — | — |
| Evidence | EVIDENCEA | EVIDENCEB |
| Safety | ●●●●● | ●●●●● |
| Legal (US) | USOTC | USOTC |
| PubMed refs | 1800 | 980 |
The comparison in plain English
Auto-generated from dataCreatine and Glycine are both in the amino-acid category respectively. Creatine The most-studied performance supplement in history, now well-evidenced as a cognitive enhancer in its own right. Glycine Smallest amino acid, inhibitory neurotransmitter and sleep enhancer.
Bottom line
Creatine (evidence A, safety 5/5) has a weaker evidence base than Glycine (evidence B, safety 5/5). Creatine has the slightly cleaner safety profile. For users new to either, the higher-evidence option is the safer first try.
Choose Creatine if
Creatine is the better fit when your goal aligns with its mechanism (Phosphorylated by creatine kinase to phosphocreatine, the fastest available ATP buffer in the cell (millisecond timescale)) and the dose range (3000–5000mg) suits your protocol. Half-life is 3h.
Choose Glycine if
Glycine is the better fit when your goal aligns with its mechanism (The simplest amino acid and a direct inhibitory neurotransmitter at glycine receptors concentrated in the brainstem and spinal cord) and the dose range (3000–5000mg) suits your protocol. Half-life is 1h.