Enhanced sleep quality and duration
Improves sleep onset, quality, and daytime alertness
Glycine
Non-essential amino acid crucial for sleep quality, collagen synthesis, and detoxification support
Scientific nameGlycine
FormulaC2H5NO2
Molecular weight75.07 g/mol
CAS56-40-6
95
absorption score
9
safety / 10
15
USD per month
5
documented interactions
Check it against something
Glycine with:
- Amylase
- Ashwagandha
- Avocado Oil
- BCAA (Branched-Chain Amino Acids)
- Beetroot Powder
- Beta-Alanine
- Bifidobacterium lactis
- Bifidobacterium longum
- Bovine Collagen
- Caffeine
- Calcium
- Calcium Bone Formula
- Calcium Carbonate
- Casein Protein
- Chicken Collagen
- Choline (Bitartrate)
- Chondroitin Sulfate
- Coconut Oil
- Collagen Peptides
- Comprehensive Immune Support Complex
- Comprehensive Multivitamin-Mineral Complex
- Creatine HCL
- Creatine Monohydrate
- D-Mannose
- DHA
- Electrolyte Blend
- EPA
- Fish Oil (EPA/DHA)
- Folate (5-MTHF)
- Ginger
- Iron Fumarate
- Iron Sulfate
- Joint Mobility Formula
- Keratin
- Krill Oil
- L-Carnitine
- L-Citrulline
- Lactase
- Lactobacillus acidophilus
- Lactobacillus rhamnosus
- Lipase
- Magnesium Citrate
- Magnesium Glycinate
- Magnesium Oxide
- Marine Collagen
- Melatonin
- Modafinil
- Olive Oil Extract
- Omega-3 + Curcumin + Vitamin D Triple Anti-Inflammatory Formula
- Papain
- Protease
- Saccharomyces boulardii
- Turmeric
- Vitamin B12 (Cyanocobalamin)
- Vitamin B12 (Methylcobalamin)
- Vitamin C (Ascorbic Acid)
- Vitamin C (Sodium Ascorbate)
- Vitamin D3
- Whey Protein
- Zinc Gluconate
Nothing found
82
out of 100
Works better together
Compatible. Timing differs, so follow each supplement's own window.
What it does
mechanism and evidence for each claimImproved collagen synthesis and joint health
Essential building block for collagen and connective tissue
Enhanced detoxification support
Supports liver detoxification and glutathione production
Improved cognitive function and memory
Supports brain health and cognitive performance
Reduced inflammation and oxidative stress
Provides anti-inflammatory and antioxidant benefits
Others take these for the same thing
Same goal, different mechanism — check any of them against this one
Melatonin
Sleep support & circadian rhythm
0.5-3mg
A
50%
Ashwagandha
Stress management & energy
300-600mg
A
75%
Magnesium Glycinate
Superior absorption sleep & muscle support
200-600 mg
A
90%
Collagen Peptides
Skin health & joint support
5-15g
B
85%
Bone Broth Collagen
Gut healing & collagen support
20-40g powder
B
85%
Vitamin B7 (Biotin)
Hair, skin & nail health
300-5000 mcg
A
80%
Every pair we checked
12 combinations scored by the engine
Glycine + Caffeine
Caffeine may counteract sleep-promoting effects
Needs attention
52
Glycine + Creatine Monohydrate
No documented interaction either way
No known interaction
70
Glycine + Calcium Carbonate
No documented interaction either way
No known interaction
70
Glycine + Whey Protein
No documented interaction either way
No known interaction
70
Glycine + Lactase
No documented interaction either way
No known interaction
70
Glycine + Bovine Collagen
No documented interaction either way
No known interaction
70
Glycine + DHA
No documented interaction either way
No known interaction
70
Glycine + Turmeric
No documented interaction either way
No known interaction
70
Glycine + Fish Oil (EPA/DHA)
No documented interaction either way
No known interaction
70
Glycine + Marine Collagen
No documented interaction either way
No known interaction
70
Glycine + Magnesium Oxide
Enhanced relaxation and sleep quality
Works better together
78
Glycine + Vitamin D3
Both essential for collagen synthesis
Works better together
82
Dosage
Daily3-10g
Sleep support3g before bed
Collagen support5-10g daily
Detox support3-5g daily
Therapeutic10-15g daily
Before you take it
VeganYes
When to expect it
First Effects1-3 days for sleep benefits
Peak Benefits2-6 weeks for sustained sleep and collagen benefits
Deficiency DevelopmentWeeks to months with inadequate synthesis or intake
Toxicity OnsetVery rare, mainly mild sedation
How to measure it
MarkerPlasma glycine levels or sleep quality assessments
Optimal200-400 μmol/L
Deficient below<150 μmol/L
FrequencyOnly if monitoring sleep disorders or collagen health
What people actually reported to the FDA
CAERS, 6 reports naming it as the suspectMost reported effects
Named as the suspect
6 reports
of 8 that mention it at all
Serious outcome
83%
hospitalisation, emergency room or worse
Other Serious or Important Medical Event3
Hospitalization2
Visited Emergency Room2
Reports are voluntary and unverified — they record what someone experienced while taking something, not what the compound caused. Counts skew towards products people take a lot of, and a serious outcome is more likely to be reported than a mild one, so these are not rates. How we filter them →
What actually reaches you
The label counts the carrier, your body does not
Absorption
Very high 95 of 100 · best absorbed form of this compound
Delivered daily
6175 mg
Cost per 100 mg delivered
$0.01 comparative — uses the absorption score, not a measured percentage
Works better with
+
Vitamin C
Both essential for collagen synthesis
Complementary roles in collagen formation and antioxidant function · level A
+
Magnesium
Enhanced relaxation and sleep quality
Complementary effects on nervous system relaxation · level B
+
Proline Hydroxyproline
Other collagen amino acids work synergistically
Complete collagen amino acid profile · level AWhat not to take with Glycine
!
Caffeine
Caffeine may counteract sleep-promoting effects
Opposing effects on nervous system arousal · moderate significance
!
Strychnine
Blocks glycine receptors (toxicological concern only)
Competitive antagonist at glycine receptors · theoretical significanceMedication interactions
Discuss these with a pharmacist before combiningMay enhance sedative effects
What to do: Monitor for excessive sedation
May reduce effectiveness of antipsychotic
What to do: Monitor psychiatric symptoms
Available forms
Glycine (Free Form): Sleep enhancement, Collagen support, Excellent safety, Inexpensive
Food sources
Bone broth
2-5g per cup · 95
Gelatin
2-3g per tablespoon · 95
Meat and poultry
1-2g per 100g · 90
Fish and seafood
1-2g per 100g · 90
Too little
- Poor sleep quality and insomnia
- Joint pain and poor collagen health
- Impaired detoxification capacity
- Poor wound healing
- Muscle weakness and fatigue
- Cognitive issues and poor memory
- Increased inflammation
Too much
- Excellent safety profile:
- Mild daytime drowsiness
- Digestive upset with very large doses
- Generally very well tolerated
Who benefits most
sleep-disorders-insomnia
Effective for improving sleep quality and reducing sleep onset time
3g 30-60 minutes before bed
collagen-joint-health
Essential building block for collagen and connective tissue
5-10g daily
detoxification-support
Supports liver detoxification and glutathione production
3-5g daily
aging-anti-aging
Supports collagen production and cellular repair
5-10g daily
cognitive-enhancement
Supports brain health and cognitive function
3-5g dailyWhere to buy it
Look for Glycine at 3-10g per serving. The form that matters here is Glycine (Free Form).
Find on Amazon
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How it works
- Activates glycine receptors and NMDA receptors for calming effects
- Essential component of collagen providing every third amino acid
- Required for glutathione synthesis and phase II detoxification
- Inhibitory neurotransmitter in brain and spinal cord
- Essential for creatine synthesis and cellular energy
- Important for proper methylation and one-carbon metabolism
Key findings
what the evidence supports- Effective for improving sleep quality and reducing sleep onset time
- Essential building block for collagen and connective tissue
- Important for detoxification and glutathione synthesis
- Excellent safety profile with minimal side effects
Sources: NIH Examine.com · data reviewed 2026-08-02
Compiled by Denis, who maintains this database and holds no medical qualification — every figure here is sourced or derived, never asserted. How we calculate it →
Common questions
What are the benefits of Glycine?
Documented effects: Enhanced sleep quality and duration; Improved collagen synthesis and joint health; Enhanced detoxification support; Improved cognitive function and memory. Improves sleep onset, quality, and daytime alertness
How much Glycine should you take per day?
The common daily range is 3-10g. By goal — sleep support: 3g before bed; collagen support: 5-10g daily; detox support: 3-5g daily; therapeutic: 10-15g daily.
When is the best time to take Glycine?
Bedtime. First effects are typically reported within 1-3 days for sleep benefits.
What are the side effects of Glycine?
At excessive doses: Excellent safety profile:, Mild daytime drowsiness, Digestive upset with very large doses, Generally very well tolerated. Safety rating at normal doses is 9 out of 10.
What should you not take with Glycine?
Separate it from Caffeine, Strychnine by two to four hours. Caffeine may counteract sleep-promoting effects
Does Glycine interact with medications?
Documented interactions with sleep-medications, clozapine. Discuss these with a pharmacist before combining.
How do you know if you need Glycine?
The marker is Plasma glycine levels or sleep quality assessments, optimal range 200-400 μmol/L. Common deficiency signs: Poor sleep quality and insomnia, Joint pain and poor collagen health, Impaired detoxification capacity, Poor wound healing.