Amino acids
Glycine
Sleep · collagen
Inhibitory neurotransmitter; collagen synthesis, sleep depth, glutathione precursor. Common dose 3 g before bed.
What Glycine does
Glycine is the smallest amino acid and triple-jobbed: it's an inhibitory neurotransmitter in the spinal cord and brainstem, the most abundant amino acid in collagen (33% of all collagen residues), and a precursor to glutathione, heme, creatine, and bile acids. The body can synthesize glycine, but at a rate that probably falls short of total demand — particularly when collagen turnover is high. Three grams before bed is the most-studied dose for sleep depth and morning alertness.
Food sources of Glycine
Approximate Glycine content per serving. Whole-food intake counts toward your daily total alongside any supplemental dose.
| Food | Serving | Glycine |
|---|---|---|
| Bone broth | 1 cup | 0.5–2 g |
| Pork rinds | 1 oz | 1.5 g |
| Chicken skin (cooked) | 1 oz | 1.2 g |
| Gelatin powder | 1 tbsp | 2 g |
| Cooked salmon | 3 oz | 1 g |
| Beef (cooked) | 3 oz | 1.2 g |
Signs of Glycine deficiency
- ●No classical deficiency syndrome — glycine is conditionally essential
- ●Chronic suboptimal intake may contribute to poor connective tissue repair, low glutathione, sleep fragmentation
Who needs more Glycine
Groups and situations where Glycine requirements rise or status commonly runs low:
- ●Diets that exclude collagen-rich tissues (skin, bone, connective tissue)
- ●Heavy training/recovery loads with high collagen turnover
- ●Sleep depth and onset (clinical-trial-supported at 3 g pre-sleep)
How Glycine appears on labels
Supplement labels list Glycine under several names depending on the chemical form used. Any of these on an ingredients panel counts toward your Glycine intake:
- glycine
- l-glycine
Best supplements for Glycine
Top-scoring supplements in our catalog that list Glycine on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
Deep dive
For mechanism of action, dosing protocols, evidence grade, and interaction warnings on Glycine, see the full encyclopedia entry:
Glycine encyclopedia entry →Conditions where Glycine has evidence
Glycine appears on the supplement list for the following condition pages — each links to the full evidence summary, dose, and lifestyle context.
Research on Glycine
Peer-reviewed studies in our research database that reference Glycine. Each entry links to a detailed methodology review.
- Kawai N, Sakai N, Okuro M, et al., 2015 · NeuropsychopharmacologyThe sleep-promoting and hypothermic effects of glycine are mediated by NMDA receptors in the suprachiasmatic nucleus
- Bannai and Kawai, 2012 · Journal of Pharmacological SciencesNew therapeutic strategy for amino acid medicine: glycine improves the quality of sleep
- Yamadera W, Inagawa K, Chiba S, et al., 2007 · Sleep and Biological RhythmsGlycine ingestion improves subjective sleep quality in human volunteers
Guides covering Glycine
Long-form articles in our guide library that go deeper on Glycine — comparisons, protocols, and reviews.
Frequently asked questions
What is the daily target for Glycine?
What foods are highest in Glycine?
What is the best form of Glycine to supplement?
What are the signs of Glycine deficiency?
Who is most at risk for low Glycine?
Related amino acids
Track your full intake
Formulate's free web app aggregates Glycine (and ~40 other nutrients) across every supplement in your stack — flagging underdoses, overlaps, and upper-limit overshoots in one view.
Track your intake free →Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Targets and upper limits are general adult reference values; individual needs vary by age, sex, pregnancy status, and clinical context.