L-Glutamine
Research Reliability -
The most abundant amino acid in the body, supporting gut lining integrity, immune function, and muscle recovery.
Appetite
Mood
Sleep
L-Glutamine
Description
L-Glutamine is a conditionally essential amino acid that becomes critical during periods of physical stress, illness, or intense training. It is the primary fuel source for enterocytes (intestinal lining cells) and plays a key role in maintaining gut barrier integrity, supporting intestinal permeability, and supporting mucosal immune function. Athletes use it to reduce muscle soreness and support recovery, while clinicians recommend it for individuals with intestinal permeability, inflammatory bowel conditions, or post-surgical recovery. The powder form allows for flexible dosing and is easily mixed into water or protein shakes.
Effects
First week
may ease gut discomfort for some
Weeks 1–4
Ongoing
How It Feels
Mostly a quiet gut and recovery supporter with little acute sensation. People with gut-lining issues sometimes report calmer digestion over a few weeks. It mixes tastelessly into water and is easy to tolerate.
Evidence
Evidence Strength
Moderate (some human RCTs)
Caveats
Strongest evidence is in specific gut-permeability and critical-illness contexts; general gut-health or muscle-recovery claims in healthy adults are less supported.
Usage
Commonly Referenced Starting Amount
5 g/day
Commonly Referenced Amount
5–15 g/day is common in gut-support use; clinical settings have used up to 30 g/day
Referenced Upper Limit
No upper limit has been established; roughly 14 g/day has a long track record of tolerability
Onset
1–4 weeks (gut lining)
Biomarkers to Track
Subjective
(Daily)
Gut comfort after meals (1–10)
Bloating and gas frequency
Sugar and alcohol cravings
Objective
(Quarterly)
Intestinal permeability (lactulose)
Calprotectin (gut inflammation)
Plasma glutamine level
Very safe at normal doses.
People with significant liver disease should moderate it.
Expecting dramatic effects, when its benefits are subtle and gut-focused.
Disclaimer
This information is for educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure, or prevent any disease. Consult a qualified healthcare provider before starting any new supplement, especially if you are pregnant, nursing, taking medication, or managing a health condition.
Zhou Q et al. (2019). Gut. RCT (glutamine and intestinal permeability in IBS-D). PMID: 30554159.
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