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    Amino AcidsSynthetic

    Glycine

    Simplest amino acid acting as an inhibitory neurotransmitter (glycine and NMDA-coagonist receptors), collagen building block (~33% of collagen mass), and metabolic intermediate.

    Last reviewed: 2026-06-23 · 1 indexed study

    Evidence Score
    68/100
    Sleep qualityCollagen synthesisCognitive functionCalm focus
    Data Completeness3/4 · 75%
    Evidence ScoreDosageSafetyLinked Studies

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    Overview

    Glycine is a non-essential amino acid that improves sleep onset and quality (3 g pre-bed), supports collagen synthesis, and provides calming neurotransmission via glycine receptors.

    Mechanism & Function

    Mechanism of Action

    Lowers core body temperature via cutaneous vasodilation (facilitating sleep onset), supports collagen/glutathione synthesis, and modulates NMDA receptor activity.

    Physiological Role

    RCTs show 3 g glycine pre-bed improves subjective and objective sleep quality, reduces sleep latency, and improves next-day cognitive performance.

    Primary Pathways

    Glycine receptor activationNMDA co-agonist siteCutaneous vasodilation/thermoregulationCollagen/glutathione synthesis

    Performance / Health Relevance

    Useful for athletes recovering from sleep debt; pairs with collagen for skin/joint support.

    Evidence Review

    Overall68/100
    Human Clinical74/100
    Meta-AnalysisN/A

    No meta-analyses or systematic reviews indexed for this ingredient yet.

    Mechanistic80/100
    Real-World70/100
    Safety94/100

    Dimensions marked N/A have no indexed evidence of that class. They are shown as unavailable rather than scored.

    Practical Use & Dosage

    Minimum Effective Dose
    3 g pre-bed
    Optimal Range
    3–5 g pre-bed (sleep); 10 g/day collagen support
    Upper / Caution Level
    ~30 g/day short-term
    Timing
    60 min before bed
    Best Format
    Powder (sweet taste), capsule
    Bioavailability
    ~95% absorbed.
    Absorption Considerations
    Active intestinal transport; rapid plasma rise.

    Safety & Interactions

    Side Effects

    • •Mild GI upset at high doses
    • •Rare drowsiness

    Contraindications

    • Schizophrenia on clozapine — discuss

    Drug Interactions

    • •Clozapine

    Who Should Avoid

    • •Severe renal impairment

    Monitoring

    None routine.

    Frequently Asked Questions

    Auto-generated from indexed evidence — dosage, safety, interactions, and more.

    When is Glycine typically used or indicated?

    Glycine is most commonly used for: Sleep quality, Collagen synthesis, Cognitive function, Calm focus. RCTs show 3 g glycine pre-bed improves subjective and objective sleep quality, reduces sleep latency, and improves next-day cognitive performance.

    How does Glycine work?

    Lowers core body temperature via cutaneous vasodilation (facilitating sleep onset), supports collagen/glutathione synthesis, and modulates NMDA receptor activity.

    What is the recommended dose of Glycine?

    The optimal range is 3–5 g pre-bed (sleep); 10 g/day collagen support. with a minimum effective dose of 3 g pre-bed. Best taken: 60 min before bed. Upper / caution level: ~30 g/day short-term.

    What are the side effects of Glycine?

    Reported side effects include: Mild GI upset at high doses; and Rare drowsiness. Monitoring: None routine.

    Does Glycine interact with medications?

    Known or theoretical interactions: Clozapine. Always check with a clinician before combining with prescription medication.

    Who should avoid Glycine?

    Glycine is generally not recommended for: Severe renal impairment; and Schizophrenia on clozapine — discuss.

    How strong is the evidence for Glycine?

    Evidence level: Moderate (overall score 68/100), based on 1 indexed study on SuppIndex.

    Research & References (1)

    Glycine ingestion improves subjective sleep quality

    RCT2007Moderate
    PubMed

    3 g glycine improved subjective sleep, reduced fatigue, and shortened polysomnographic sleep latency.

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    Research Overview

    Moderate Evidence
    1Total Studies
    1Human Trials
    0Meta-Analyses
    2007Latest Study
    0Animal / In Vitro
    0Athlete Studies
    Primary data sourceGeneral Population
    Pooled evidence (meta-analysis / systematic review)No

    Cite this ingredient

    One-click citation export in APA, MLA, Chicago, BibTeX, or HTML. The URL below is stable and safe to link.

    Stable URL

    https://thesuppindex.com/ingredients/glycine

    SuppIndex. (2026). Glycine: Evidence summary, dosage and clinical studies. Retrieved October 16, 2026, from https://thesuppindex.com/ingredients/glycine

    Based on 1 indexed studies · Evidence level: Moderate.

    Goal Ratings

    Sleep
    Recovery
    General Health
    Focus

    Stack Compatibility

    Pair with magnesium, l-theanine for sleep; with collagen and vitamin C for connective tissue.

    MagnesiumL-TheanineCollagen

    Related evidence

    Compare Glycine with other researched ingredients.

    Last reviewed Jun 2026