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Open WellbeingWhat the studies actually measured

Mood, stress and thinking

Glycineand Cognitive performance

Two sources here, and they say different things: one found no clear difference in cognitive performance and one reported mixed results.

How sure anyone can be

Low certainty, level 2 of 4

Further research is likely to change this.

The most certain of the two findings here; each record carries its own.

The numbers reported

No number has been put on this yet. Two sources recorded only which way the numbers went — for now, that is all we have here.

Two sources, newest first

We do not pick between these or average them into one number.

What we read is the published abstract, not the full paper, so a blank below may still be printed in the paper itself. A fixed rule worked this out from the source’s own fields. Nobody checked this rating by hand.

  • Randomised trial, 2008

    Low certainty, level 2 of 4

    The cognitive effects of modulating the glycine site of the NMDA receptor with high-dose glycine in healthy controls.

    Hum Psychopharmacol. 2008;23(2):151-9. doi:10.1002/hup.904. PMID:17972276.

    Number reported
    Not in the abstract
    Which way it went
    No clear difference
    Likely range
    Not in the abstract
    Source’s own words
    not reported in the abstract
    Who was studied
    Adult
    Compared with
    placebo
    Amount taken
    0.8 g/kg body weight, single oral dose
    For how long
    1 days
    Disagreement between studies
    Not in the abstract
    Kind of record
    Journal article
    How this rating was reachedstarts at High, 2 steps down: risk of bias and imprecision
    1. Starts at High
    2. Risk of bias brought it down to Moderatethe abstract reports no risk-of-bias or quality appraisal, so study limitations cannot be ruled outNot in the abstract
    3. Imprecision brought it down to Lowthe abstract reports no confidence interval for the estimateNot in the abstract
    4. Ends at Low2 steps down.
    Checked, nothing to step it down for
    indirectness
    Inconsistency
    One study, so there was nothing to disagree

    Imprecision stops at the first check that applies; others may apply too.

    AI-reviewed & signed — an AI agent re-read this finding against the saved source and checked that the quote, the numbers, the units and the direction match it. No person read it. The owner authorised the agent to sign the batch with the owner's key, and every build rechecks that signature against these exact bytes.

    Read the abstract on PubMed

  • Randomised trial, 1999

    Very low certainty, level 1 of 4

    Beneficial effects of glycine (bioglycin) on memory and attention in young and middle-aged adults.

    J Clin Psychopharmacol. 1999;19(6):506-12. doi:10.1097/00004714-199912000-00004. PMID:10587285.

    Number reported
    Not in the abstract
    Which way it went
    Mixed results
    Likely range
    Not in the abstract
    Source’s own words
    not reported in the abstract
    Who was studied
    Adult
    Compared with
    placebo
    Amount taken
    Recorded detail — mg/d
    For how long
    Not in the abstract
    Disagreement between studies
    Not in the abstract
    Kind of record
    Journal article
    How this rating was reachedstarts at High, 3 steps down: risk of bias, imprecision and inconsistency
    1. Starts at High
    2. Risk of bias brought it down to Moderatethe abstract reports no risk-of-bias or quality appraisal, so study limitations cannot be ruled outNot in the abstract
    3. Imprecision brought it down to Lowthe abstract reports no confidence interval for the estimateNot in the abstract
    4. Inconsistency brought it down to Very lowpooled studies disagree on the direction of effectReported in the abstract
    5. Ends at Very low3 steps down.
    Checked, nothing to step it down for
    indirectness

    Imprecision stops at the first check that applies; others may apply too.

    AI review could not confirm it — an AI agent re-read this finding against the saved source and at least one check failed. The batch record names the check and quotes the sentence that caused the doubt. No person read it.

    Read the abstract on PubMed

What is still missing from these readings

  • None gives a number at all, only which way it went.
  • Two give no likely range, so how precise those numbers are is unknown.
  • Two do not say how many people took part.
  • For how long — One of Two readings: Not in the abstract.

Something nobody wrote down is never a zero and never a guess.

Still to read for Glycine

One of the seven things on our list for Glycine has no reading here yet:

  • Sleep onset latency

Still to read means nobody here has got to it, not that it was tried and did nothing or that no research exists. A pairing on no list is not a gap: we never set out to read it.

Read next

This is a library, not advice. No recommendation, no dose, no diagnosis, no ranking. We never ask about your symptoms, and nothing here is tailored to you.