L-Glutamine
Also known as: Glutamine
The most abundant amino acid in muscle and blood — essential for gut health, immune function, and recovery from intense exercise.
What it is
L-Glutamine is the most abundant free amino acid in the body, comprising 60% of the free amino acid pool in skeletal muscle. While classified as conditionally essential (the body can synthesize it), demands during illness, surgery, intense training, or GI disease can outpace production. It serves as the primary fuel source for intestinal epithelial cells and immune cells, making it a key nutrient for gut integrity and immune function.
How it works
In the gut, glutamine fuels the enterocytes lining the intestinal wall and maintains tight junction protein expression — preventing intestinal hyperpermeability ('leaky gut'). In immune cells, it is the preferred fuel for lymphocytes and macrophages, particularly during high-demand states like infection or surgery. In muscle, glutamine participates in nitrogen balance and protein synthesis and may reduce exercise-induced cortisol.
Clinical dose range
5–20 g/day
For gut health and general immune support: 5–10 g/day. For post-surgical recovery, critical illness, or intense athletic training: 10–20 g/day. No meaningful benefit to exceeding 20 g/day for most applications. Take away from high-protein meals to avoid competitive absorption.
Forms comparison
What to look for on the label
- Free-form L-Glutamine (not di-peptide forms without clinical evidence)
- Pharmaceutical or fermentation-derived glutamine (not hydrolyzed protein sources)
- Third-party tested for purity
- No unnecessary fillers or excipients in powder form
Health goals supported
Safety & dosing notes
Very well tolerated at typical doses. GI discomfort possible at very high doses (>30 g/day). Theoretical concern in individuals with liver disease or history of seizures (glutamine is a precursor to glutamate). Not recommended for those with active cancer without medical supervision (cancer cells utilize glutamine as fuel).
SuppsBuddy validates dose against the clinical range and flags products providing sub-gram doses of glutamine (insufficient for gut or immune applications). Free-form L-glutamine receives the highest form score.
Frequently asked questions
What is L-Glutamine?
L-Glutamine is the most abundant free amino acid in the body, comprising 60% of the free amino acid pool in skeletal muscle. While classified as conditionally essential (the body can synthesize it), demands during illness, surgery, intense training, or GI disease can outpace production. It serves as the primary fuel source for intestinal epithelial cells and immune cells, making it a key nutrient for gut integrity and immune function.
How does L-Glutamine work?
In the gut, glutamine fuels the enterocytes lining the intestinal wall and maintains tight junction protein expression — preventing intestinal hyperpermeability ('leaky gut'). In immune cells, it is the preferred fuel for lymphocytes and macrophages, particularly during high-demand states like infection or surgery. In muscle, glutamine participates in nitrogen balance and protein synthesis and may reduce exercise-induced cortisol.
What is the typical clinical dose range for L-Glutamine?
5–20 g/day. For gut health and general immune support: 5–10 g/day. For post-surgical recovery, critical illness, or intense athletic training: 10–20 g/day. No meaningful benefit to exceeding 20 g/day for most applications. Take away from high-protein meals to avoid competitive absorption.
What forms of L-Glutamine should I look for?
Free-form L-Glutamine powder: Most bioavailable and practical; cost-effective at the required gram-level doses | L-Glutamine capsules: Convenient but expensive at higher doses due to capsule volume limitations
Is L-Glutamine safe?
Very well tolerated at typical doses. GI discomfort possible at very high doses (>30 g/day). Theoretical concern in individuals with liver disease or history of seizures (glutamine is a precursor to glutamate). Not recommended for those with active cancer without medical supervision (cancer cells utilize glutamine as fuel). This information is educational and is not medical advice.
How does SuppsBuddy evaluate L-Glutamine?
SuppsBuddy validates dose against the clinical range and flags products providing sub-gram doses of glutamine (insufficient for gut or immune applications). Free-form L-glutamine receives the highest form score.
Related ingredients
This page is for educational purposes only. These statements have not been evaluated by the FDA. This information is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before starting any supplement.