L-Glutamine

Your intake

What each level of l-glutamine does

Approximate dose-response bands. Individual response varies — these are starting points, not prescriptions.

1. Severely lowYOU ARE HERE

   0 g – 1.65 g

   Well below target. Risk of deficiency symptoms tied to gut · recovery.

2. Insufficient

   1.65 g – 5 g

   Below the recommended daily target. Long-term adequacy not assured.

3. Adequate

   5 g – 7.5 g

   Daily target met. Standard nutritional support for gut · recovery.

4. Therapeutic

   7.5 g – 10 g

   Common for specific health goals. Check the evidence for your situation before sustaining this level.

5. Diminishing returns

   10 g – +

   Past the point where extra intake typically helps. Evidence for further benefit is thin.

Overview

Most abundant free amino acid in plasma and muscle; conditionally essential during catabolic stress (burns, trauma, critical illness). Primary fuel for enterocytes and immune cells. Often marketed for gut health, recovery, and immunity — the evidence is strongest in clinical catabolic states.

Functions

• ●Primary metabolic fuel for enterocytes and lymphocytes
• ●Nitrogen donor for purine/pyrimidine and amino sugar synthesis
• ●Substrate for renal ammoniagenesis (acid-base regulation)
• ●Glutamate precursor (CNS)
• ●Maintains intestinal tight junction integrity

Mechanism

Glutaminase in enterocytes hydrolyses glutamine to glutamate + ammonia; glutamate feeds the TCA cycle for ATP. Plasma glutamine falls rapidly in catabolic states because demand outpaces muscle release. Pharmacologic glutamine supports gut barrier function (reducing bacterial translocation) and immune cell proliferation in critical illness.

Benefits

• ●Reduces infection rate and ICU mortality in critically ill (varies by trial; recent meta-analyses softer)
• ●Reduces intestinal permeability in IBD and short bowel syndrome
• ●May reduce chemo-induced mucositis severity
• ●Modest reduction in upper respiratory infection rate in endurance athletes
• ●Not effective for muscle gain in well-fed adults

Deficiency

Frank deficiency is rare. Functional deficiency in burns, trauma, sepsis, and immediately post-surgical states.

Excess

Well-tolerated to ~30 g/day in studies. Avoid in liver cirrhosis or hepatic encephalopathy — glutamine catabolism elevates ammonia.

Forms

• L-glutamine free-form powder
  Standard form; affordable; dissolves easily
• L-glutamine capsules
  Convenient; pill burden at gram doses
• L-alanyl-L-glutamine (dipeptide)
  Better stability and bioavailability in IV/parenteral use

Food sources

• Beef (cooked) · 3 oz1.5 g
• Eggs (whole) · 1 large0.5 g
• Cottage cheese · 1/2 cup1.5 g
• Tofu · 1/2 cup0.7 g
• White rice (cooked) · 1 cup0.3 g
• Cooked salmon · 3 oz1 g

Supplement forms

L-glutamine free-form powder at 5 g/day is the conventional starting dose. For clinical IBD/IBS protocols, 5–10 g in divided doses with food. Don't take if you have liver cirrhosis or hepatic encephalopathy — glutamine elevates ammonia.

Bioavailability

~30–40% reaches systemic circulation due to first-pass enterocyte and hepatic metabolism. This is the point — gut and liver are primary consumers. Dipeptide forms (alanyl-glutamine) bypass first-pass and are preferred in IV/parenteral use.

Longevity relevance

No direct longevity signal in healthy adults. Adequate dietary intake is sufficient. Pharmacologic use is condition-specific (catabolic states, gut barrier dysfunction).

Relationships

References

• Examine — Glutaminereview
• Heyland — REDOXS trial of glutamine in critical illness (NEJM 2013)study

About L-Glutamine

Most abundant amino acid; gut barrier, immune cell fuel, recovery. Common dose 5 g/day.

Role

Gut · recovery

Daily target

5 g (TR)

Also called

l-glutamine, glutamine