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Supplement

Glycine

Glycine is the simplest amino acid, a building block for proteins like collagen that also acts as a calming messenger in the brain and helps nerve cells respond to other signals. Most research on it centers on schizophrenia, where three small studies with about 50 people found symptoms improved when it was added to usual medication, and the evidence is moderate. Cognition also improved in one very small group of 17 people, but that evidence is limited, so these results are early and mostly apply to people already on antipsychotic medicines.

Sources: PMID 14732596; PMID 38269529

Best evidence
Grade B
Conditions studied
2
Outcomes
5
Graded outcomes
0120

Evidence by condition

  • Strong
  • Moderate
  • Limited
  • Very limited

2 conditions

Schizophrenia

Schizophrenia: outcomes studied for Glycine
GradeOutcomeEffectSizeStudiesPeopleStudies list
Schizophrenia symptoms

Small Improvement

Improves (the measure goes down)Small effect3 studies50 people

Studies that measured schizophrenia symptoms

Cognition

Small Improvement

Improves (the measure goes up)Small effect17 people

Sleep Health

Sleep Health: outcomes studied for Glycine
GradeOutcomeEffectSizeStudiesPeopleStudies list
Cognition

Small Improvement

Improves (the measure goes up)Small effect11 people
Sleep QualityImproves (the measure goes up)1 study33 people

Studies that measured sleep quality

Fatigue SymptomsImproves (the measure goes down)26 people

What the published studies found

1 automated reading

Automated reading of the published studies (Decosa evidence engine), for outcomes Dr. Grey has not graded yet. It is not a Dr. Grey grade and does not change one. How it is read

  • Sleep quality

    The studies read are too weak to tell whether Glycine changes sleep quality. They lean toward an improvement, which is not enough to claim one. The evidence is very weak.

    1 study counted of 9 read: 1 trial (20 people in the trials).
    1. Crossover trial, 2021; 20 people; urology outpatients with overactive bladder symptoms: improves. sleep latency, latency to first nighttime urination Dietary glycine improves urine storage symptoms in urology outpatientsPubMed 33793143

    Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.

Key findings

  • Schizophrenia symptomsSchizophreniaImproves (the measure goes down)
  • CognitionSchizophreniaImproves (the measure goes up)

Shop the evidence-backed picks

Third-party tested Glycine products, in the forms the graded studies used where we can match them.

  • Grade B

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Studies cited

4 studies from PubMed

  1. The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteersFront Neurol · PMID 22529837
  2. Efficacy of pharmacological agents for the management of treatment-resistant schizophrenia: a network meta-analysis.Expert Rev Clin Pharmacol · PMID 38269529
  3. High-dose glycine added to olanzapine and risperidone for the treatment of schizophreniaBiol Psychiatry · PMID 14732596
  4. Glutamatergic drugs for schizophrenia.Cochrane Database Syst Rev · PMID 16625590

Protocols that include Glycine