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Glycine
Glycine is the simplest amino acid, serving as an inhibitory neurotransmitter and a key building block for proteins, collagen, and glutathione. It promotes deep, restorative sleep, reduces anxiety, and supports cognitive function through NMDA receptor co-agonism.
Benefits
What is Glycine?
Glycine is the smallest and simplest amino acid, yet it plays an outsized role in brain function, sleep quality, and overall health. As a neurotransmitter, glycine acts on inhibitory glycine receptors in the brainstem and spinal cord, and as a co-agonist at excitatory NMDA receptors throughout the brain - giving it a unique dual role in neural signalling.
Glycine has gained significant attention as a sleep aid after Japanese researchers discovered that 3 grams taken before bed dramatically improves subjective sleep quality, reduces daytime fatigue, and enhances cognitive performance the following day. Unlike many sleep aids, glycine achieves this without sedation - it lowers core body temperature, which is a natural signal for sleep onset.
Beyond sleep, glycine is essential for the production of glutathione (the body's master antioxidant), collagen (the most abundant protein in the body), and creatine. Its role as an NMDA receptor co-agonist also supports memory, learning, and synaptic plasticity.
- Thermoregulation: Glycine lowers core body temperature by dilating peripheral blood vessels via NMDA receptors in the suprachiasmatic nucleus, mimicking the natural temperature drop that triggers sleep.
- Inhibitory neurotransmission: Acts on glycine receptors in the brainstem and spinal cord, producing calming, anxiolytic effects and reducing neural excitability.
- NMDA receptor co-agonism: Serves as an obligatory co-agonist at the glycine-binding site of NMDA receptors, facilitating synaptic plasticity, learning, and memory formation.
- Glutathione synthesis: Essential precursor for glutathione (GSH), the body's primary endogenous antioxidant, supporting detoxification and neuroprotection.
- Anti-inflammatory effects: Activates glycine-gated chloride channels on immune cells, reducing inflammatory cytokine production.
- For sleep: 3 grams taken 30–60 minutes before bed (the dose used in most clinical studies)
- For cognitive support: 1–3 grams per day
- For antioxidant support: 1–3 grams per day, often combined with N-acetylcysteine (NAC) for glutathione synthesis
- Taste: Naturally sweet - dissolves easily in water and is pleasant to drink
- Upper limit: Well-tolerated up to 9 grams per day in studies. Higher doses may cause mild gastrointestinal effects.
- Side effects: Very few. Possible mild nausea or soft stools at high doses.
- Drug interactions: May interact with clozapine (antipsychotic). Consult a doctor if taking psychiatric medications.
- Pregnancy: Glycine is a naturally occurring amino acid present in many foods and is generally considered safe, though supplementation during pregnancy should be discussed with a healthcare provider.
- Safety profile: Excellent. Glycine is endogenous, non-toxic at supplemental doses, and does not cause tolerance or dependence.
Natural Sources & Forms
- Endogenous production: The body synthesises glycine from serine and threonine
- Food sources: Bone broth, gelatin, meat (especially skin and connective tissue), fish, dairy, legumes, and spinach
- Collagen supplements: Collagen peptides are approximately 33% glycine by weight
- Supplements: Available as pure powder (pleasant sweet taste), capsules, and tablets. Inexpensive and widely available.
Research Studies
Frequently Asked Questions
Glycine is the simplest amino acid, serving as an inhibitory neurotransmitter and a key building block for proteins, collagen, and glutathione. It promotes deep, restorative sleep, reduces anxiety, and supports cognitive function through NMDA receptor co-agonism.
The key benefits of Glycine include: Anxiety & Calm, Cognitive Enhancement, Longevity, Memory, Mood, Sleep, Stress Relief.
Thermoregulation: Glycine lowers core body temperature by dilating peripheral blood vessels via NMDA receptors in the suprachiasmatic nucleus, mimicking the natural temperature drop that triggers sleep. Inhibitory neurotransmission: Acts on glycine receptors in the brainstem and spinal cord, producing calming, anxiolytic effects and reducing neural excitability. NMDA receptor co-agonism: Serves as an obligatory co-agonist at the glycine-binding site of NMDA receptors, facilitating synaptic plasticity, learning, and memory formation. Glutathione synthesis: Essential precursor for glutathione (GSH), the body's primary endogenous antioxidant, supporting detoxification and neuroprotection. Anti-inflammatory effects: Activates glycine-gated chloride channels on immune cells, reducing inflammatory cytokine production.
For sleep: 3 grams taken 30–60 minutes before bed (the dose used in most clinical studies) For cognitive support: 1–3 grams per day For antioxidant support: 1–3 grams per day, often combined with N-acetylcysteine (NAC) for glutathione synthesis Taste: Naturally sweet - dissolves easily in water and is pleasant to drink Upper limit: Well-tolerated up to 9 grams per day in studies. Higher doses may cause mild gastrointestinal effects.
Side effects: Very few. Possible mild nausea or soft stools at high doses. Drug interactions: May interact with clozapine (antipsychotic). Consult a doctor if taking psychiatric medications. Pregnancy: Glycine is a naturally occurring amino acid present in many foods and is generally considered safe, though supplementation during pregnancy should be discussed with a healthcare provider. Safety profile: Excellent. Glycine is endogenous, non-toxic at supplemental doses, and does not cause tolerance or dependence.
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