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, preventing leaky gut, 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
gut lining and recovery support builds
Ongoing
most useful under high training or gut stress
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.
Usage
Entry Dose
2.5g
Standard Dose
5–10g
Max Dose
20g
Onset
1–4 weeks (gut lining)
Combinations
Pairs well with
Synergistic
Bacillus coagulans — glutamine repairs gut lining; probiotics restore healthy flora together
Zinc + vitamin A — gut integrity trio; each supports different aspects of mucosal repair
Collagen peptides — collagen provides glycine and proline; glutamine fuels enterocytes
Avoid combining
Contraindicated
Seizure medications (Depakote, Lamictal) — glutamine is a glutamate precursor; may lower seizure threshold
Hepatic encephalopathy — impaired ammonia clearance; glutamine raises ammonia in liver failure
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.
Moderate (some human RCTs)
Strongest evidence is in specific gut-permeability and critical-illness contexts; general gut-health or muscle-recovery claims in healthy adults are less supported.
Zhou Q et al. (2019). Gut. RCT (glutamine and intestinal permeability in IBS-D). PMID: 30554159.