Glycine
Also known as: aminoacetic acid, 2-aminoacetic acid, Gly, G
Effective Dosage
No established dose from provided studies
What the Science Says
Glycine is a simple amino acid your body makes and uses in many biological processes, including building collagen and acting as a signaling molecule in the brain. One small clinical trial tested oral glycine supplementation (about 0.12 g/kg daily) in people with alcohol use disorder and found it raised blood glycine levels by 125% but did not reduce alcohol cravings or consumption. Research on glycine's role in liver disease and brain chemistry is ongoing, but no provided studies confirm clear benefits from glycine supplements in healthy adults.
What It Doesn't Do
Won't reduce alcohol cravings — a clinical trial showed no effect. Not proven to improve sleep, build collagen, or boost cognition based on the provided evidence. No data from these studies supports claims about muscle recovery or anti-aging. The fact that glycine is involved in collagen structure doesn't mean taking it as a pill rebuilds your joints.
Evidence-Based Benefits
Glycine acts as an endogenous agonist at glycine receptors (GlyRs) in brain reward regions and may modulate dopamine transmission; however, oral glycine supplementation at 0.12 g/kg raised serum glycine by 125% but did not reduce alcohol craving or consumption in individuals with AUD (PMID: 41189445). Glycine transporter-1 (GlyT1) inhibition has been explored as a pharmacological strategy for erythropoietic protoporphyria and cognitive impairment in schizophrenia, with the former showing significant protoporphyrin-IX reduction (PMID: 41390126) but the latter failing to improve cognition in large phase 3 trials (PMID: 41233083). Glycine also plays a structural role in collagen triple helix formation as part of the repeating Gly-Xaa-Yaa sequence (PMID: 41931485).
Weak EvidenceEffective at: No established dose from provided studies
Source: auto-research
Absorption & Bioavailability
Unknown from provided studies — one trial confirmed oral glycine raises serum levels (125% increase at 0.12 g/kg), but absorption efficiency and clinical relevance were not characterized.
Red Flags to Watch For
- Most marketing claims (sleep, collagen, detox, cognition) are not supported by the clinical trials provided here
- The one human clinical trial found no meaningful benefit for its primary outcome (alcohol craving and intake)
- Glycine is widely used in dental and lab procedures (e.g., air-polishing powder) — products may conflate these uses with supplement benefits
- Over 1,000 registered supplement products contain glycine, suggesting heavy commercialization far outpacing the clinical evidence
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-04-06