Glycine
Amino Acid ·Exploratory record · not publication-reviewed ·Updated July 13, 2026
The simplest amino acid with surprisingly powerful effects on sleep quality, collagen synthesis, and neuroprotection. A key component of glutathione.
Exploratory record, not a reviewed medical publication.
See the editorial and medical-review policies for the publication gate.
This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.
What the research says.
A quick, data-only summary. The full evidence, dosing, and sources are below.
Glycine is an amino acid most often used for sleep quality, collagen synthesis, glutathione support. NutriStack rates the overall evidence as moderate. A typical adult dose is 3–5 g daily (before bed for sleep), commonly taken as pure glycine powder. This profile indexes 18 sources.
The bottom line
Evidence rating moderate. Most-documented uses: sleep quality, collagen synthesis, glutathione support. 18 sources indexed (2006–2025), with 0 interaction records on file.
How it works, mechanistically.
Core mechanism
Inhibitory neurotransmitter binding to glycine receptors in the brainstem and spinal cord. Lowers core body temperature (via peripheral vasodilation) to promote sleep onset. One of three amino acids in glutathione (with cysteine and glutamate). Major component of collagen (every third residue).7,10
Dosing & protocol.
Take 3g about 1 hour before bed for sleep; sweet taste makes it easy to take in water1,8
What it actually costs.
Real-world pricing across three quality tiers. Assumes Pure Glycine Powder.
Assumes 3 g nightly from goal dosage. Vendor basis: BulkSupplements powder, NOW/iHerb, Vitacost, and Amazon marketplace; capsules cost more than powder. Updated 2026-05-28.
The same dose, as food.
How much you'd eat to match a supplemental dose.
Collagen-rich foods are the most glycine-dense whole-food approach.
Food can provide glycine, but not always as predictably as a powder.
Full safety detail.
Side effects
- Very safe; mild GI upset at very high doses
- Rare drowsiness
Contraindications
- Clozapine (may reduce efficacy)
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Randomized controlled trials
5- 1Supplementing Glycine and N-Acetylcysteine (GlyNAC) in Older Adults Improves Glutathione Deficiency, Oxidative Stress, Mitochondrial Dysfunction, Inflammation, Physical Function, and Aging Hallmarks: A Randomized Clinical TrialPMIDKumar P et al. · J Gerontol A Biol Sci Med Sci · 2023
GlyNAC supplementation for 16 weeks in older adults improved glutathione levels, oxidative stress, mitochondrial function, inflammation, and physical function.
- 2Glycine increases fat-free mass in malnourished haemodialysis patients: a randomized double-blind crossover trialPMIDGenton L, Teta D, Pruijm M et al. · Journal of cachexia, sarcopenia and muscle · 2021
Genton L, Teta D, Pruijm M et al.. Glycine increases fat-free mass in malnourished haemodialysis patients: a randomized double-blind crossover trial. Journal of cachexia, sarcopenia and muscle. 2021
- 3The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteersPMIDBannai M et al. · Front Neurol · 2012
3g glycine before bedtime significantly reduced fatigue and improved daytime sleepiness induced by acute sleep restriction.
- 4Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changesBannai M, Kawai N, Ono K et al. · Sleep Biol Rhythms · 2012
- 5New therapeutic strategy for amino acid medicine: glycine improves the quality of sleepSource linkedPMIDInagawa K, Hiraoka T, Kohda T et al. · J Pharmacol Sci · 2006
Reviews & position papers
12- 6The complex role of glycine N-methyltransferase in metabolism-a reviewPMIDSuzauddula M, Islam MN, Ahmed T · Molecular biology reports · 2025
Suzauddula M, Islam MN, Ahmed T. The complex role of glycine N-methyltransferase in metabolism-a review. Molecular biology reports. 2025
- 7Glycine receptors: Structure, function, and therapeutic implicationsPMIDMizzi N, Blundell R · Molecular aspects of medicine · 2025
Mizzi N, Blundell R. Glycine receptors: Structure, function, and therapeutic implications. Molecular aspects of medicine. 2025
- 8An Update of the Promise of Glycine Supplementation for Enhancing Physical Performance and Recovery.PMIDRamos-Jimenez A, Hernndez-Torres RP, Hernndez-Ontiveros DA, Ortiz-Ortiz M, Lpez-Fregoso RJ, Martnez-Sanz JM et al. · Sports (Basel) · 2024
Review found glycine supplementation shows promise for enhancing physical performance and recovery through anti-inflammatory, antioxidant, and collagen-synthesis-promoting mechanisms.
- 9The effect of glycine administration on the characteristics of physiological systems in human adults: A systematic reviewPMIDRazak MA et al. · Nutrients · 2023
Longer-term glycine administration improved sleep in healthy populations, though studies had small sample sizes with high risk of bias.
- 10Cesium activates the neurotransmitter receptor for glycinePMIDFricke S, Harnau M, Hetsch F et al. · Frontiers in molecular neuroscience · 2023
Fricke S, Harnau M, Hetsch F et al.. Cesium activates the neurotransmitter receptor for glycine. Frontiers in molecular neuroscience. 2023
- 11Effects of glycine on metabolic syndrome components: a reviewPMIDImenshahidi M, Hossenzadeh H · Journal of endocrinological investigation · 2022
Imenshahidi M, Hossenzadeh H. Effects of glycine on metabolic syndrome components: a review. Journal of endocrinological investigation. 2022
- 12Glycine Signaling in the Framework of Dopamine-Glutamate Interaction and Postsynaptic Density. Implications for Treatment-Resistant SchizophreniaPMIDde Bartolomeis A, Manchia M, Marmo F et al. · Frontiers in psychiatry · 2020
de Bartolomeis A, Manchia M, Marmo F et al.. Glycine Signaling in the Framework of Dopamine-Glutamate Interaction and Postsynaptic Density. Implications for Treatment-Resistant Schizophrenia. Frontiers in psychiatry. 2020
- 13Glycine Exhibits Neuroprotective Effects in Ischemic Stroke in Rats through the Inhibition of M1 Microglial Polarization via the NF-κB p65/Hif-1α Signaling PathwayPMIDLiu R et al. · Neuroscience · 2019
Glycine inhibits ischemia-induced inflammation and promotes M2 microglial polarization, reducing infarct volume and neuronal death.
- 14Roles of dietary glycine, proline, and hydroxyproline in collagen synthesis and animal growthPMIDLi P et al. · Amino Acids · 2018
Glycine, proline, and hydroxyproline contribute to 57% of total amino acids in collagen; endogenous glycine synthesis falls short of metabolic needs by about 10g/day.
- 15Glycine transporter-1 inhibitors: a patent review (2011-2016)PMIDCioffi CL · Expert opinion on therapeutic patents · 2018
Cioffi CL. Glycine transporter-1 inhibitors: a patent review (2011-2016). Expert opinion on therapeutic patents. 2018
- 16Dietary glycine is rate-limiting for glutathione synthesis and may have broad potential for health protectionSource linkedPMIDMcCarty MF, O'Keefe JH, DiNicolantonio JJ · Ochsner J · 2018
- 17The sleep-promoting and hypothermic effects of glycine are mediated by NMDA receptors in the suprachiasmatic nucleusPMIDKawai N et al. · Neuropsychopharmacology · 2015
Glycine promotes sleep by lowering core body temperature via peripheral vasodilation through NMDA receptor activation in the SCN.
Common questions.
Quick answers about Glycine, drawn from the data on this page.
What is Glycine?
The simplest amino acid with surprisingly powerful effects on sleep quality, collagen synthesis, and neuroprotection. A key component of glutathione.
What is Glycine used for?
Commonly cited benefits of Glycine include: Sleep quality; Collagen synthesis; Glutathione support; Neuroprotection; Blood sugar support. NutriStack rates the overall evidence as moderate.
What is a typical dose of Glycine?
A typical adult dose of Glycine is 3–5 g daily (before bed for sleep). The commonly recommended form is Pure glycine powder. These are general ranges, not personalized advice; confirm the right dose with a clinician.
What are the side effects of Glycine?
Reported side effects include very safe; mild gi upset at very high doses, rare drowsiness. This is educational information; check with a healthcare professional before use.
How strong is the evidence for Glycine?
NutriStack rates this as Moderate, meaning several aligned RCTs or one large RCT plus supporting reviews. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.
Use this with your stack
Glycine in NutriStack.
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