What does the evidence show about Glycine (longevity / metabolic)'s effects?

Read Off Label rates the evidence for Glycine (longevity / metabolic) as Moderate and the benefit magnitude as med, producing an overall grade of B+ (7.1/10). NIA Interventions Testing Program (Miller 2019, Aging Cell) — 8% glycine diet extended median lifespan ~4-6% in both sexes across 3 independent sites with reduced pulmonary adenocarcinoma mortality.

What safety findings are reported for Glycine (longevity / metabolic)?

Glycine (longevity / metabolic) has a low risk profile in the database. Low (well-tolerated to tens of g/day; mild GI at high doses; sweet taste) Legal status: OTC.

What doses or routes are reported for Glycine (longevity / metabolic)?

10-15 g/day in divided doses (covers age-related collagen-turnover shortfall); 100 mg/kg/day in MASLD/obesity trials This is context from studies, approved labeling, clinical practice, or documented use; it is not individualized guidance and does not establish safety.

Rankings / Longevity — Supplements

Glycine (longevity / metabolic)

Longevity · Amino acid / methionine restriction mimetic

Tier B+

Reviewed by Read Off Label · Last reviewed Jun 8, 2026 · How we grade

methionine-restrictionautophagyglutathioneone-carbonmasldcollagenotc

7.1 / 10

Tier B+

Ev 6 Bn 5 Sf 9

Bottom line

Read Off Label grades Glycine (longevity / metabolic) as B+ (7.1/10) based on moderate evidence, med benefit magnitude, and a low-risk safety profile.

Studied, labeled, or reported-use context: 10-15 g/day in divided doses (covers age-related collagen-turnover shortfall); 100 mg/kg/day in… — OTC; not individualized guidance.

What the evidence says

NIA Interventions Testing Program (Miller 2019, Aging Cell) — 8% glycine diet extended median lifespan ~4-6% in both sexes across 3 independent sites with reduced pulmonary adenocarcinoma mortality. Soultoukis 2023 (PMID 37004845) reviews glycine's role mimicking methionine restriction via GNMT-mediated SAM consumption; methionine restriction itself robustly extends lifespan across species. Razak 2023 PRISMA systematic review (GeroScience) covered 11 physiological systems in humans; cardiovascular and nervous-system signals were strongest. 2025 Singapore RCT (Cossiga et al, Scientific Reports, n=19 severe obesity, 100 mg/kg × 2 weeks) — no weight change but significant reductions in plasma triglycerides and aminotransferases plus improved glutamate-serine-glycine MASLD index, supporting glycine as a MASLD-adjacent intervention; larger trial NCT07285135 ongoing. Hannan 2024 Nutrients update review (PMID 39453231) covers exercise/recovery applications. Background: typical Western diet supplies ~3-5 g glycine vs. ~10-15 g daily metabolic demand for collagen turnover and one-carbon flux — chronic shortfall worsens with age. Distinct from Sleep entry (3 g pre-bed) and GlyNAC (paired with NAC for glutathione).

Mechanism

Conditionally essential amino acid; ~33% of collagen by residues; substrate for glutathione/creatine/heme/purines/bile salts; key acceptor for GNMT (glycine N-methyltransferase) which consumes excess SAM (S-adenosylmethionine) — acts as a methionine restriction mimetic; lowered SAM/mTOR signaling permits autophagy; plasma glycine declines with age and is reduced in obesity/MASLD

Studied, labeled, or reported dose & route

10-15 g/day in divided doses (covers age-related collagen-turnover shortfall); 100 mg/kg/day in MASLD/obesity trials

This records doses and routes described in studies, approved labeling, clinical practice, or documented use. It is not individualized guidance and does not establish safety; context changes with indication, formulation, health history, monitoring, and other medicines.

Citations

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Common questions

What does the evidence show about Glycine (longevity / metabolic)'s effects?: Read Off Label rates the evidence for Glycine (longevity / metabolic) as Moderate and the benefit magnitude as med, producing an overall grade of B+ (7.1/10). NIA Interventions Testing Program (Miller 2019, Aging Cell) — 8% glycine diet extended median lifespan ~4-6% in both sexes across 3 independent sites with reduced pulmonary adenocarcinoma mortality.
What safety findings are reported for Glycine (longevity / metabolic)?: Glycine (longevity / metabolic) has a low risk profile in the database. Low (well-tolerated to tens of g/day; mild GI at high doses; sweet taste) Legal status: OTC.
What doses or routes are reported for Glycine (longevity / metabolic)?: 10-15 g/day in divided doses (covers age-related collagen-turnover shortfall); 100 mg/kg/day in MASLD/obesity trials This is context from studies, approved labeling, clinical practice, or documented use; it is not individualized guidance and does not establish safety.
How does Glycine (longevity / metabolic) work?: Conditionally essential amino acid; ~33% of collagen by residues; substrate for glutathione/creatine/heme/purines/bile salts; key acceptor for GNMT (glycine N-methyltransferase) which consumes excess SAM (S-adenosylmethionine) — acts as a methionine restriction mimetic; lowered SAM/mTOR signaling permits autophagy; plasma glycine declines with age and is reduced in obesity/MASLD

This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.