Glutamine vs Glycine: Repairs vs Dreams
These two amino acids are "conditionally essential," meaning your body makes them, but not enough during times of stress.
L-Glutamine is the primary fuel for your gut cells (enterocytes). Glycine is the primary inhibitor in the brainstem (spinal cord).
| Feature | L-Glutamine | Glycine |
|---|---|---|
| Primary System | Digestive / Immune | Nervous System |
| Sleep Effect | Neutral (Can be stimulating) | Positive (Lowers temp) |
| Taste | Neutral | Sweet |
| Dose | 5g - 10g | 3g - 5g |
Mechanisms: Fuel vs Signal
L-Glutamine: The Brick
Glutamine provides the nitrogen and carbon that cells use to build DNA and proteins. It is critically important for repairing "leaky gut" (intestinal permeability). It also helps muscle recovery.
Glycine: The Switch
Glycine acts as a neurotransmitter. Before REM sleep, glycine floods the brainstem to paralyze your muscles (atonia) so you don't act out your dreams. Taking it helps trigger deep sleep.
What it means
Glutamine rebuilds the house. Glycine turns off the lights.
Which One Matches Your Goal?
For Stomach Issues
Winner: L-Glutamine.
If you have IBS, bloating, or ulcers, Glutamine is the first-line therapy. Glycine has some anti-inflammatory effects but is nowhere near as potent for the gut.
For Sleep
Winner: Glycine.
Taking 3g of Glycine one hour before bed significantly improves sleep quality and reduces morning drowsiness. Glutamine can sometimes convert to glutamate (excitatory) in the brain, so it creates anxiety for some people at night.
The Verdict
Choose L-Glutamine if: You have gut issues or are recovering from intense exercise.
Choose Glycine if: You want deeper, more restorative sleep or to detoxify from excessive methionine (meat) intake.