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Glycine

Well Researched

Cheapest amino acid supplement on the shelf with two real but limited use cases: (1) 3 g pre-bed for subjectively better sleep — evidence…

Aliases (5)

Gly · G · Aminoacetic acid · 2-Aminoacetic acid · GLYCINE

TYPICAL DOSE

500-1000 mg

Daily

ROUTE

Oral (powder)

Oral / mixed in liquid

CYCLE

None needed. Daily-safe indefinitely

Continuous / daily

STORAGE

Room temp; sealed, dry

Cool, dry place

Overview

What is Glycine?

Glycine is the simplest amino acid and an inhibitory neurotransmitter in the CNS. Sold as a supplement for sleep, cognition, and metabolic support. Sweet-tasting and well-tolerated at gram doses.

Key Benefits

Improves subjective sleep quality and reduces sleep onset latency at 3 g pre-bed. May enhance cognition the following day after better sleep. Supports collagen synthesis and methylation balance. Bedtime cooling effect via thermoregulation.

Mechanism of Action

Activates inhibitory glycine receptors (strychnine-sensitive) in spinal cord and brainstem, plus serves as a co-agonist at NMDA receptor glycine sites. Pre-bed glycine lowers core body temperature, promoting sleep onset.

Pharmacokinetics

PeakHalf-life

Approximate curve — visual aid only, not data-precise PK

▸ Mixing & scoop math Powder

Mixing

• Mix into 8-16 oz cold water (or sports drink / protein shake). Most powders dissolve in < 30 sec with a brisk stir.
• If using a shaker, add liquid first, then powder, then shake — minimizes foam and clumps.
• Hot water is fine for most amino acids and creatine; avoid for heat-sensitive compounds (NAC degrades above ~60 °C).
• Drink within 5-10 min of mixing — most powders are stable in solution but taste degrades.

Research Indications

Most Effective

1. Inhibitory neurotransmitter at the glycine receptor (GlyR)

The strychnine-sensitive glycine receptor is a pentameric ligand-gated chloride channel, structurally related to GABA-A. It is the domina…

Effective

2. NMDA receptor glycine-site co-agonist (forebrain)

Glycine (and D-serine) is an obligatory co-agonist at the NMDA glutamate receptor — both glutamate AND a glycine-site agonist must bind f…

Investigational

3. Thermoregulation via peripheral vasodilation (the actual sleep mechanism)

This is the best-evidenced mechanism for glycine's sleep effect. Pre-bed glycine (3 g) produces peripheral vasodilation (likely via NMDA-…

Most Effective

4. Other roles (relevant context, not primary for users in this archetype)

- Glutathione synthesis substrate. Glutathione (GSH) is glycine + cysteine + glutamate. Glycine availability becomes rate-limiting for GS…

Research Protocols

Disclaimer: These are commonly discussed research protocols and not medical advice.

Goal

Dose

Frequency

Solo Use

Cycle

Goal:1-2 g

Dose:—

Frequency:—

Solo:—

Cycle:—

Goal:3 g

Dose:—

Frequency:—

Solo:—

Cycle:—

Goal:5-10 g

Dose:3 g

Frequency:—

Solo:—

Cycle:—

Goal:10-60 g/day (split doses)

Dose:—

Frequency:—

Solo:—

Cycle:—

Peptide Interactions

magnesium-glycinate

Synergistic

users in this archetype often already take 400 mg elemental Mg as glycinate (V4). The glycinate form contributes a small additional glycine load (~1-2 g equi…

l-tryptophan

Synergistic

different mechanism (substrate vs thermoregulation); could co-administer pre-bed without antagonism. Not recommended for users in this archetype because of p…

l-theanine (V4: 200 mg)

Synergistic

different mechanism (GABA/glutamate), additive subjective relaxation. Fine to co-administer.

n-acetyl-cysteine (V4: 1200 mg)

Synergistic

provides cysteine; combined with glycine improves glutathione synthesis substrate base. The "GlyNAC" Sekhar protocol uses ~100 mg/kg glycine + ~100 mg/kg NAC…

magnesium (any form)

Synergistic

Mg is a calming pre-bed adjunct via NMDA modulation + GABA-A facilitation; glycine + Mg is a common pre-bed pair. Already in V4 via Mg-glycinate + magtein.

apigenin (V5 plan)

Synergistic

different mechanism (GABA-A PAM). Additive sedation likely mild; safe stack.

collagen peptides

Synergistic

collagen is glycine-rich; if user is taking collagen for joints/skin, additional glycine supplementation has diminishing returns.

Strychnine

Avoid

joke. Strychnine is a glycine receptor antagonist; not a real-world concern.

No clinically meaningful contraindications

Avoid

at supplement doses. Glycine is one of the safest amino acid supplements.

Quality Indicators

✓

Single-ingredient, COA-backed

Look for single-ingredient powders from vendors who publish a Certificate of Analysis.

✓

Mixes cleanly

Should dissolve or suspend cleanly in water without large clumps once stirred.

Off taste or smell

Strong rancid, fishy, or chemical odors can indicate oxidation or contamination.

✗

Color or texture change over time

A powder that yellows, clumps, or hardens over time may be hygroscopic and degraded.

What to Expect

Onset
30-60 min after dose. The most common subjective is mild warmth or relaxation, not sedation.
Peak
60-120 min. Faster sleep onset reported by responders; some report no effect at all.

Side Effects & Safety 5

Side Effects

1None reliably at 3 g. Most users report nothing.
2Mild sweet aftertaste with powder form (intended; no GI implication).
3GI upset (loose stool, mild nausea, bloating) at higher doses (5+ g) or rapid escalation. Dose-dependent; usually resolves by splitting or reducing dose.
4Daytime drowsiness if dose is too late or too high — uncommon at 3 g pre-bed.
5Vivid dreams (10-20%); usually transient.

When to Stop

No serious adverse effect signal at typical supplement doses (1-10 g/day) in healthy adults. Glycine has GRAS status, used in IV nutrition formulas at multiple grams.
High-dose schizophrenia trial reports: mild GI symptoms, occasional headache, no organ toxicity at 30-60 g/day over months.
Glycine encephalopathy (nonketotic hyperglycinemia) — a rare inborn error of glycine metabolism that produces severe neonatal encephalopathy. Affected individuals would not tolerate glycine supplementation, but this is a genetic disorder presenting in infancy, not a side effect of supplementation in healthy adults.
Hypotensive interaction with antihypertensives — theoretical (peripheral vasodilation), no clinical reports at 3 g doses.
None. Glycine is one of the cleanest amino acid supplements safety-wise. No tolerance to monitor, no withdrawal, no organ toxicity at supplement doses.
EFSA / various risk assessments: no formal UL set. Doses up to 9-10 g/day in healthy adults appear safe.
Schizophrenia trial doses up to 60 g/day tolerated by most subjects with GI as the main limit.
Practical ceiling: 5 g daily-driver is well within safe bounds; 10 g/day for short-term (days-weeks) is reasonable; >10 g chronic only with monitoring (but no clear use case for healthy adults).