Tier 2 — strong

The effect of glycine administration on the characteristics of physiological systems in human adults: A systematic review

Soh J, Raventhiran S, Lee JH, Lim ZX, Goh J, Kennedy BK, Maier AB
GeroScience 2024 46(1):219-239

Bibliography

PubMed
PMID 37851316
PubMed Central
PMC10828290
DOI
10.1007/s11357-023-00970-8
Funding
No dedicated funding statement was identified in the retrieved full text; this does not establish absence of funding.
Competing interests
The authors declared no conflicts of interest.

Study snapshot

DesignSystematic review of human intervention studies
ModelHuman studies
SampleAdult human reports spanning 18 healthy and 34 diseased study populations
InterventionGlycine across doses, routes and comparators; combinations excluded
DurationSearch through April 2022; exposures up to 14 days in healthy groups and 4 months in diseased groups
EndpointsEleven physiological systems; Sleep and neuropsychiatric measures; Metabolic and clinical outcomes

What the study showed, in plain terms

This systematic review maps glycine administration across adult physiological systems. It identifies encouraging signals but emphasizes the small, biased and heterogeneous evidence base, particularly for healthy-person sleep and aging claims.

Key findings

  • Healthy-population sleep studies were small and judged at high risk of bias.
  • Most longer-duration evidence came from clinical populations.
  • The review did not establish prevention or reversal of human aging.

What this study can and cannot tell us

An any-route literature review is not equivalent to evidence for a single oral supplement regimen.

Its search predates several newer trials, and some table values conflict with original abstracts.

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Insulin resistance and glycine metabolism in humans
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Alterations in glycine metabolism in obesity and chronic metabolic diseases - an update on new advances
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Glycine as a conditionally essential amino acid and its relationship to l-serine
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Editorial review

Reviewed by the Biohack Blueprint research team

Last verified

Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction