Glycine
Also known as: Aminoacetic acid
Glycine is a simple amino acid people commonly explore before bed for relaxation and sleep quality. Some small studies are encouraging, but evidence is limited. It has a mildly sweet taste and is generally well tolerated.
Snapshot
What this page can tell you: That glycine is one of the two components studied together with NAC as GlyNAC, and how the combination was studied — plus that glycine on its own is only lightly studied here.
What it cannot: That glycine treats or prevents any condition, or that you should combine it with NAC. Glycine-alone efficacy is not source-reviewed on this page yet.
🧩 Stack insights — how this fits into a schedule
GlyNAC (Glycine + NAC) — Glycine has been studied together with NAC as GlyNAC in an older-adult trial. Studied together does not mean everyone combining them needs to — review the comparison before adding items.
Relationship insights are informational only — they describe what is commonly discussed or studied, not what you should take. Not medical advice; review your routine with a clinician or pharmacist.
NAC alone vs glycine alone vs GlyNAC (combination)
Same comparison shown on the NAC/GlyNAC pages — a discussion aid, not a recommendation.
| Option | Evidence status | Studied populations | Safety cautions |
|---|---|---|---|
| NAC alone | Established medical uses; general supplement benefits mixed/uncertain. | Broad supplemental use, less characterized. | Bleeding/surgery category; asthma/bronchospasm; regional regulation. |
| Glycine alone | Only lightly studied here; glycine-alone outcomes not source-reviewed on this page. | Not characterized on this page. | Generally well tolerated; review sedative/serotonergic interactions. |
| GlyNAC (combination) | One small randomized trial in older adults (16 weeks). | Older adults / specific group. | Inherits NAC cautions; no standardized dose. |
Pairing and combination notes are informational — they describe what is commonly discussed or studied, not what you should take. Review combinations with a clinician or pharmacist.
📊 Studied dosing
Studied dose, not a personal recommendation. These are amounts used in specific studies or populations — not guidance for you.
| Intervention | Dose | Form | Frequency | Duration | Population | Outcome studied | Source | Limitations |
|---|---|---|---|---|---|---|---|---|
| Glycine + NAC (GlyNAC), combined | 100 mg/kg/day each of glycine and NAC (per body weight) | Capsules (pharmacist-filled) | Daily | 16 weeks (older adults); 2 weeks (younger adults) | 24 older adults (12 GlyNAC / 12 alanine placebo); 12 young adults | Glutathione levels, oxidative stress, mitochondrial function, inflammation, physical function markers | PMID 35975308 · DOI 10.1093/gerona/glac135 (full text) | Small single trial; combination design cannot separate glycine vs NAC; specific older-adult population; not a general-population or personal-dose claim. |
This row is the glycine + NAC combination study — not glycine alone. Studied dose, not a personal recommendation.
🕒 Timing
When: Bedtime
Food: With or without food
Commonly taken shortly before bed.
💊 Common use range
3 g
Generally well tolerated; follow product guidance.
Ranges are informational, not a recommended dose. Talk to a professional about what is right for you.
⚠️ Commonly noted interactions (supplements)
None listed.
Often about absorption or timing rather than danger — separating doses is common. This list is not exhaustive.
🧭 Caution level
Ask a clinician or pharmacist before use.
- Commonly discussed as relaxing/sedating
- Sedative / CNS-depressant interaction
- Serotonergic (SSRI/SNRI) interaction
- Evidence not fully source-reviewed yet
Caution level is an informational summary of commonly discussed caution categories and doses — not a safety rating, approval, or medical advice. Low caution does not mean safe for you.
🩺 Medication caution categories
- Sedatives / CNS depressants
- Antidepressants (SSRIs/SNRIs)
🏥 Surgery & procedure caution
Not a well-established surgical concern; share your supplement list.
If you have a procedure scheduled, bring your full supplement list to your surgical and anesthesia team. Do not stop prescribed medication unless your clinician tells you to. Do not start or stop supplements based only on this app.
✅ Quality checklist
- Prefer products with third-party testing or a certificate of analysis (COA).
- Check the label for the exact form and the elemental or active amount per serving.
🧩 Commonly paired with
🔁 Alternatives
🗣️ Questions for a professional
- Is Glycine appropriate alongside my medications and health history?
- Is there a test or check that would tell us whether I actually need it?
⚖️ Evidence limitations
- Glycine-alone efficacy is not source-reviewed on this page yet (marked needs-review elsewhere).
- The combination evidence is a single small older-adult trial.
❓ Frequently asked
What is GlyNAC?
GlyNAC is the name for taking glycine together with N-acetylcysteine (NAC). Both are amino-acid-related compounds the body can use toward making glutathione.
Is GlyNAC the same as NAC?
No. NAC is N-acetylcysteine on its own. GlyNAC is NAC plus glycine taken together. Some research studied the combination rather than NAC alone.
Why combine glycine with NAC?
The mechanism rationale (not an outcome claim) is that the body builds glutathione from cysteine — supplied by NAC — and glycine. Researchers studied supplying both together. Mechanism is not the same as proven benefit for an individual.
Is GlyNAC better than NAC?
The available research does not establish the combination as better for most people, or that anyone needs it. One randomized trial studied it in older adults. Whether NAC, glycine, or the combination fits your situation is a question for a clinician or pharmacist.
What has GlyNAC actually been studied for?
In a small 2023 randomized trial, the glycine + NAC combination was studied in older adults over 16 weeks, measuring glutathione, oxidative stress, mitochondrial function, inflammation, and physical-function markers. It is one early-stage trial in a specific population — not evidence for the general public.
What should someone review before adding GlyNAC?
That it is a combination concept (not a single standard product), the NAC-related cautions (bronchospasm risk in asthma, bleeding/surgery category, regional regulatory status), and — with a clinician or pharmacist — whether any of it is relevant to them. Compare NAC alone, glycine alone, and the combination first.
🔬 Evidence snapshot
Overall evidence level here is listed as "Limited evidence". A detailed, source-reviewed evidence summary has not been completed yet.
🧪 Forms & quality
Needs evidence review — no source-reviewed information yet. We only show dose and monitoring details after they have been checked against reputable sources.
See the supplement glossary for what form names like "L-", chelated, or standardized extract mean.
📏 Dose & monitoring
Needs evidence review — no source-reviewed information yet. We only show dose and monitoring details after they have been checked against reputable sources.
Evidence vs. burden: Not yet reviewed
😐 Commonly reported side effects
- Uncommon; mild digestive upset in some people
Non-exhaustive and individual.
🔄 Cycling & breaks
Not typically cycled.
📅 Daily use notes
Often taken nightly as part of a wind-down routine.
📋 Source review status
Needs evidence review
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