Glycine for longevity

At a Glance

Mechanism of Action

Supplies the glycine half of glutathione synthesis, which becomes rate-limiting with age. Separately acts as an inhibitory neurotransmitter at glycine and NMDA receptors, and lowers core body temperature — the likely route by which it shortens time to sleep onset.

Glycine is typically taken orally as powder — it is naturally sweet and dissolves easily, 60 minutes before bed for sleep; split through the day at higher doses. Supplies the glycine half of glutathione synthesis, which becomes rate-limiting with age. Separately acts as an inhibitory neurotransmitter at glycine and NMDA receptors, and lowers core body temperature — the likely route by which it shortens time to sleep onset. Effective range is 3 g - 15 g, with 3 g before bed for sleep; 10-15 g daily as part of GlyNAC being the most-studied dose. It does not require food, and fasted dosing is often preferred for absorption or timing reasons.

Dosage & Timing

Splitting the daily dose keeps plasma concentrations steadier, which matters for compounds with a shorter half-life or narrower therapeutic window.

How to Take

1. Start at the lower end of the range (3 g - 15 g) for the first 7–10 days to gauge tolerance.
2. Titrate up to the target dose of 3 g before bed for sleep; 10-15 g daily as part of GlyNAC once tolerance is confirmed.
3. Fasted or with a light snack is acceptable — food is not required.
4. Best timing: 60 minutes before bed for sleep; split through the day at higher doses. Keep the daily window consistent so effects are legible against baseline.
5. Missed dose: skip and resume normally; never double up.

Absorption & Bioavailability

• Absorption for Glycine is generally reliable at 3 g before bed for sleep; 10-15 g daily as part of GlyNAC; splitting the daily dose into two smaller servings can smooth plasma concentrations.
• Hydrate adequately — most oral supplements are absorbed better when total daily water intake is above 30 ml/kg.

Cycling & Stacking Strategy

• Most users run Glycine continuously and reassess every 12 weeks with bloods and a symptom log.
• If effect plateaus, a 2–4 week wash-out often restores responsiveness by resetting receptor sensitivity and feedback loops.
• Common stack: N-acetylcysteine, Magnesium glycinate, L-theanine. Introduce one addition at a time so you can attribute effect and side effect.
• Rotate related supplements seasonally rather than layering five products in the same category.

Who This Is For

What to Monitor

Reported Benefits

• Improved glutathione, oxidative stress, mitochondrial function, inflammation and insulin resistance in a 24-week randomised trial of older adults
• Shortened sleep onset and improved subjective sleep quality in Japanese trials at 3 g
• Improvements in muscle strength, gait speed and cognition in the same GlyNAC trial
• Extremely cheap — one of the lowest cost-per-effect items in this database

Safety Profile

How to Choose a Quality Product

• Third-party tested — look for NSF, Informed Sport, USP or an equivalent independent COA (certificate of analysis) on the batch you're buying.
• Standardised active — the label should specify the exact active compound and its concentration, not just the botanical name.
• Minimal excipients — avoid unnecessary fillers, artificial colours and shared allergens (soy, gluten) unless you're happy to test for reactions.
• Dose per serving matches the researched range (3 g - 15 g) — many consumer products under-dose to widen margins.
• Manufactured in a cGMP-certified facility with a clear country of origin.
• Reasonable price per effective dose — cheaper products often deliver less active per capsule, so the true cost-per-dose is higher.

Common Mistakes

• Under-dosing — using 3 g - 15 g when the research uses 3 g before bed for sleep; 10-15 g daily as part of GlyNAC.
• Stopping after two weeks — most longevity-relevant endpoints need 8–12 weeks of consistent dosing before they move on bloods.
• No baseline labs, so any effect is attributed to placebo or hype rather than to the supplement.
• Stacking three or four new products in the same month — you lose all ability to attribute results.
• Buying the cheapest brand and skipping the third-party COA — potency and purity vary dramatically between manufacturers.
• Timing it inconsistently — the biological effect depends on steady exposure, not sporadic doses.

Evidence Grade — B (66/100)

Grade B — mechanism is credible and at least one human trial, pharmacokinetic study or strong observational evidence exists. Long-term effects on healthspan endpoints are still incomplete.

The primary references used to grade Glycine are listed below. Cross-check against the current literature and expect the grade to move as new human trials publish.

References

1. [1]Supplementing glycine and N-acetylcysteine (GlyNAC) in older adults improves glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, physical function and aging hallmarks: a randomized clinical trial — Journals of Gerontology: Series A, 2023
2. [2]GlyNAC supplementation in older adults improves glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, insulin resistance, endothelial dysfunction, genotoxicity, muscle strength and cognition: results of a pilot clinical trial — Clinical and Translational Medicine, 2021

Further reading: Research library → · Protocols →