L-Glutamine
The body's most abundant free amino acid. Where the evidence sits depends on context.
L-glutamine is the most abundant free amino acid in blood and muscle, and cells lining the gut use it as their preferred fuel, which is why it turns up in gut-support formulas at 5-10g doses. The body normally synthesises enough on its own, but production can fall short under severe physical stress — burns, surgery, prolonged intense training — where supplemental glutamine has real clinical support. For general users without that stress load, the evidence for benefits like muscle recovery or immune support is weaker than the marketing implies. Free-form powder and peptide-bound forms both absorb well; peptides may have a small absorption edge but rarely justify the price gap.
Forms and bioavailability
Not all forms are absorbed equally. The form on your supplement label affects how much your body can actually use.
| Form | Absorption | With food | Timing | Evidence |
|---|---|---|---|---|
| L-glutamine peptide | Higher | Either | Either | Possible |
| L-glutamine (free form) | Typical | Either | Either | Likely |
Stack Almanac tracks your glutamine intake and form, so a high daily dose from a gut-support formula doesn't quietly double up with the glutamine already in your protein powder.
Track your L-Glutamine in Stack Almanac
Last reviewed: 2026-07-22. Reference values are adult-general RDAs. Individual needs may vary. This page is for informational purposes only and is not a substitute for professional medical advice.