What Is L-Glycine?
L-glycine is a unique amino acid - it is the smallest, simplest and ONLY achiral (has no D and L forms). Despite its simplicity, glycine performs extremely diverse functions: (1) acts as an inhibitory neurotransmitter in the CNS, (2) makes up ~33% of collagen structure (every third amino acid!), (3) participates in liver detoxification (conjugates toxins), (4) is a component of glutathione, creatine, hemoglobin and DNA. Glycine also improves sleep quality through lowering body temperature and nervous system inhibition. For athletes, glycine is especially important due to sleep quality (3-5 g before sleep), connective tissue health (collagen), creatine synthesis (together with arginine and methionine) and liver protection.
L-Glycine Classification and Molecular Properties
| Property | Value |
|---|---|
| Type | Non-essential amino acid (smallest) |
| Molecular formula | C2H5NO2 |
| Molecular mass | 75.07 g/mol (smallest) |
| Codons | GGU, GGC, GGA, GGG |
| Side chain | Hydrogen atom (the only achiral amino acid) |
| Water solubility | Very good (250 g/L 20C) |
| RDA / Sports dose | No RDA; athletic 3-5 g |
L-Glycine Benefits for Athletes
Nervous System Inhibition
Glycine acts as an inhibitory neurotransmitter in the spinal cord and brainstem. It activates glycine receptors that inhibit neuron activity - this causes relaxation and calms.
Sleep Quality Improvement
3-5 g glycine before sleep lowers body temperature (through peripheral vasodilation) and activates glycine receptors - both mechanisms promote deeper and higher-quality sleep.
Collagen Synthesis (33% of Structure!)
Glycine is the most abundant collagen amino acid - it makes up about 33% of total collagen! Every third amino acid in the collagen chain is glycine. This is critically important for joint, skin and bone health.
Creatine Synthesis
Glycine, together with arginine and methionine (via SAMe), is essential for creatine synthesis in the liver and kidneys. Supplemental glycine may support endogenous creatine production.
Liver Detoxification
Glycine conjugates various toxins in the liver (e.g., benzoic acid into hippuric acid) and helps eliminate them. This is important for athletes consuming a lot of protein and supplements.
Glutathione Synthesis
Glycine is one of the three components of glutathione (the main antioxidant) (together with cysteine and glutamate). Sufficient glycine is essential for antioxidant protection.
Dosage Recommendations
- Daily requirement: The body synthesizes ~3-4 g of glycine per day
- For sleep quality: 3-5 g glycine 30-60 min before sleep
- For collagen synthesis: 3-5 g glycine per day (together with proline and lysine)
- For liver detoxification: 2-3 g glycine 2-3 times per day
- Maximum Safe Dose: 15 g per day
Scientific Research
Sleep Quality
3 g glycine before sleep reduced time to fall asleep, reduced nighttime awakenings and improved morning alertness. The effect was achieved within 2 weeks.
Body temperature
Glycine causes peripheral vasodilation, lowering body temperature by 0.3-0.5C. This is a natural signal to the body that it is 'time to sleep'.
Collagen Synthesis
Glycine + proline + lysine together with vit. C increased collagen synthesis in vitro. Glycine was the most abundantly required amino acid.
Liver protection
Glycine supplements (5 g/day) reduced ALT and AST liver enzymes in people with nonalcoholic fatty liver within 3 months.
Practical Tips
Before Sleep for Sleep Quality
Dissolve 3-5 g glycine powder in warm water and drink 30-60 min before sleep. Sweet taste - like natural 'sleep tea'.
Combine with Magnesium
Magnesium + glycine is one of the best natural sleep combinations. Magnesium relaxes muscles, glycine acts through the nervous system - synergistic effect.
For collagen synthesis
Glycine + proline + lysine + vit. C is the optimal combination for collagen production. Glycine provides quantity (33% of collagen), proline provides structure, lysine provides cross-links.
As a Sweetener
Glycine has a naturally sweet taste and can be used as a sugar substitute in coffee or tea. 1 g glycine ~ 0.6 g sugar sweetness.
L-Glycine Synergy with Other Supplements
- Glycine + Magnesium: The golden sleep combination. Magnesium relaxes muscles, glycine calms the nervous system - together they create deep, quality sleep.
- Glycine + Proline + Lysine: The collagen synthesis 'trio'. Glycine (33% of collagen) + proline (15%) + lysine (cross-links) = complete collagen building.
- Glycine + Arginine + Methionine: Creatine synthesis precursors. Glycine provides the 'backbone', arginine the amidino group, methionine the methyl group.
- Glycine + Glutamine + Cysteine: Glutathione synthesis components. Glycine is one of the three glutathione "building blocks".
Natural L-Glycine Sources in Food
| Food Product (100 g) | L-Glycine Content | Extra Benefit |
|---|---|---|
| Collagen Peptides | ~22 000 mg/100g | Concentrated source of glycine and proline |
| Bone broth | ~4 000 mg/100g | Minerals, glucosamine |
| Pork skin | ~8 000 mg/100g | Collagen-rich product |
| Chicken skin | ~5 000 mg/100g | Collagen source |
| Fish skin | ~6 000 mg/100g | Marine collagen, omega-3 |
| Spirulina | ~2 500 mg/100g | Antioxidants, B vitamins |
Collagen peptides and bone broth are the best sources of glycine. Glycine powder has a naturally sweet taste - it can be used as a healthy alternative to sugar.
Who Needs L-Glycine Supplements Most?
- Athletes with sleep disorders: Glycine is one of the best natural sleep quality improvers.
- Athletes with joint problems: Glycine makes up one third of collagen - essential for joint health.
- Strength athletes: Glycine is involved in creatine synthesis.
- Athletes taking many supplements: Glycine helps the liver detoxify various compounds.
Signs of L-Glycine Deficiency
Poor sleep quality
Difficulty falling asleep, frequent awakenings, insufficient deep sleep - glycine helps through nervous system inhibition.
Joint and skin problems
Glycine makes up 33% of collagen - its deficiency weakens connective tissue.
Reduced creatine synthesis
Lower endogenous creatine production - glycine is one of the three creatine precursors.
Liver burden
Glycine helps conjugate toxins in the liver - its deficiency makes detoxification more difficult.