Amino Acid
L-Glycine
Also known as: Glycine, L-α-Aminoacetic acid, Aminoacetic acid
A simple, non-essential amino acid with documented sleep-promoting properties through thermoregulation and GABA receptor modulation. Evidence supports its use for improving sleep latency and quality.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Every L-Glycine product we have scored
| # | Product | Score | Per serving |
|---|---|---|---|
| 1 | Nutricost Glycine Powder | 92 A | $0.17 |
| 2 | Thorne Glycine | 92 A | $0.25 |
| 3 | Pure Encapsulations Glycine | 92 A | $0.58 |
| 4 | Life Extension Glycine | 92 A | $0.13 |
| 5 | NutraBio Glycine Powder | 92 A | $0.13 |
| 6 | Pure Encapsulations NAC + Glycine powder | 88 A | $1.27 |
| 7 | Pure Encapsulations Pure Tranquility Liquid | 87 A | $1.76 |
| 8 | Life Extension Optimized Carnitine | 87 A | $0.78 |
| 9 | Thorne MediClear-SGS™ - Vanilla | 86 A- | $2.10 |
| 10 | Vital Nutrients Glycine Powder | 85 A- | $0.60 |
| 11 | NOW Foods Double Strength 5-HTP | 84 A- | $0.37 |
| 12 | Swanson GABAplex with L-Tyrosine & L-Theanine | 84 A- | $0.28 |
Scored on dose accuracy, form, label transparency and third-party testing. Per-serving cost is list price divided by servings per container. No brand pays to be listed or ranked.
Common questions
How much L-Glycine should I take?
The typical range is 3-10 g daily (most studies use 3g). Safe for long-term daily use; benefits may increase with consistent use over 2+ weeks
When should I take L-Glycine?
30-60 minutes before bed. Can take with or without food.
Which form of L-Glycine is best?
L-Glycine powder or capsules.
Is L-Glycine safe?
Commonly reported: Well-tolerated; minimal side effects at 3-10g doses, Mild GI effects possible at very high doses.
Which L-Glycine supplement scores highest?
Nutricost Glycine Powder, at 92/100. Scored on dose accuracy, form, label transparency and third-party testing — no brand pays to be listed or ranked.
Daily target & upper limit
3 g / dayL-Glycine has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:
L-Glycine dosage reference →Primary uses
- Sleep onset improvement
- Sleep quality
- Relaxation
- Collagen synthesis
How it works
- Glycine receptor agonist (inhibitory neurotransmitter)
- Promotes vasodilation and heat dissipation (core temperature reduction)
- Indirect GABA potentiation
- CNS relaxation
Dosage
- Typical range
- 3-10 g daily (most studies use 3g)
- Timing
- 30-60 minutes before bed
- With food
- Can take with or without food
- Duration
- Safe for long-term daily use; benefits may increase with consistent use over 2+ weeks
- Special populations
- Generally well-tolerated across populations
Forms
- L-Glycine powder or capsules· 70/100
Safety
Common side effects
- Well-tolerated; minimal side effects at 3-10g doses
- Mild GI effects possible at very high doses
Contraindications
- None established at typical doses
Products containing L-Glycine
Top-scoring supplements in our catalog that list L-Glycine on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
Known interactions
Evidence notes
Good RCT evidence (Japanese trials) showing 3g glycine reduces sleep latency and improves subjective sleep quality; mechanism well-characterized.
Grade B: Some human trials support key claims; further confirmation needed.
Cited research for L-Glycine
Clinical studies referenced across Formulate guides that mention l-glycine. Each links to the full study page with PubMed source + the guides that cite it.
- Kawai N, Sakai N, Okuro M, et al. (2015)Neuropsychopharmacology
The sleep-promoting and hypothermic effects of glycine are mediated by NMDA receptors in the suprachiasmatic nucleus
- Bannai and Kawai (2012)Journal of Pharmacological Sciences
New therapeutic strategy for amino acid medicine: glycine improves the quality of sleep
- Yamadera W, Inagawa K, Chiba S, et al. (2007)Sleep and Biological Rhythms
Glycine ingestion improves subjective sleep quality in human volunteers
Related in Amino Acid
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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.