What it is & primary uses
A conditionally essential amino acid promoted for recovery and gut support, but routine athletic benefits are not established.
Main benefits
- May affect gut-permeability markers in narrow heat-exercise protocols
- No reliable improvement in aerobic performance or body composition
Studied protocols
Research doses are grouped by outcome. They describe study designs—not a personal prescription.
No established effective routine dose
- Study duration
- Not established
- Interpretation
- A meta-analysis found no overall benefit for aerobic performance, body composition or immune outcomes in adult athletes.
0.25–0.9 g/kg fat-free mass
- Study duration
- Single dose 2 hours before a 60-minute run
- Interpretation
- A ten-person crossover study improved a permeability marker without improving gastrointestinal symptoms; another ten-person study at 0.3 g/kg worsened permeability.
04Food sources & equivalents＋
Can food provide a studied amount?
Glutamine occurs throughout dietary protein, but food databases and laboratory methods do not support a simple food-to-free-L-glutamine conversion.
Protein-bound glutamine plus other amino acids
- How this was estimated
- Most food protein contains glutamine, but the free amino-acid supplement used in trials differs from intact dietary protein and weight-based research doses.
- Important limitation
- Eating adequate protein supports amino-acid nutrition; it does not recreate the very large acute doses used in small exercise-heat experiments.
Food equivalents compare ingredient mass using published composition values. They do not prove equal absorption, formulation, physiological effect, safety or personal need.
Source: Composition of amino acids in foods ↗05How to take it for absorption & tolerance＋
With or without food
Experimental exercise-heat studies used acute pre-exercise dosing, but conflicting results and very large weight-based amounts prevent a general timing recommendation.
- Practical approach
- If using a conventional label serving, choose the food context that is easiest to tolerate rather than extrapolating from experimental doses.
- Watch for
- Clinical nutrition protocols and exercise-heat experiments are not interchangeable with routine fitness supplementation.
Meal guidance reflects human pharmacokinetic, clinical, official-label or evidence-review sources where available. A food pairing can change absorption or tolerability, but does not make a supplement necessary, effective or safe for every person.
Source: Glutamine and intestinal permeability during running in heat ↗06Supplement interaction check＋
An unlisted pair means no established pair-specific interaction was identified in this review—not proof that every dose, product or person is safe.
This is not proof that every dose, product or user context is safe. Medication and condition checks still apply.
07Research notes＋
Insufficient for routine athletic performance, muscle gain, recovery or body-composition claims. Small heat-exercise studies report conflicting gut-permeability results using unusually large weight-based doses.
Small exercise-in-heat studies used very large weight-based doses and reported conflicting results. Those protocols should not be converted into a routine recommendation.
08Scientific references＋
Peer-reviewed human research and formal evidence reviews. Open each source to inspect the complete paper record.
Glutamine supplementation in athletes
Dose context: Multiple forms, doses and athletic settings
Found no overall effect on aerobic performance, body composition or most measured immune outcomes.
Glutamine and intestinal permeability during running in heat
Dose context: 0.25, 0.5 or 0.9 g/kg fat-free mass 2 hours pre-exercise
Permeability markers improved dose-dependently, but gastrointestinal symptoms were low and unchanged.
Low-dose glutamine during exhaustive heat stress
Dose context: 0.3 g/kg fat-free mass 1 hour pre-exercise
The dose worsened gastrointestinal permeability and did not improve intestinal injury, microbial translocation or time to exhaustion.
09Expert & media references＋
Podcast and practitioner statements are clearly separated from research. They may explain practice or emerging ideas, but do not prove efficacy.
Dose Radar will leave this lane empty rather than invent or infer a professional opinion.