Amino Acid ·Moderate evidence ·Reviewed May 2026
Most abundant amino acid in the body, critical for gut health and immune function.
The bottom line
Evidence rating moderate. Most-documented uses: gut health, immune support, muscle recovery. 19 sources indexed (2014–2024), with 6 interaction records on file.
Core mechanism
Primary fuel for enterocytes (intestinal cells) and immune cells. Supports gut barrier integrity by maintaining tight junction proteins. Precursor for glutathione and nucleotide synthesis.1,9
Ranked by evidence and value.
Real-world pricing across three quality tiers. Assumes L-Glutamine Powder.
Assumes 5-10 g/day. Vendor basis: BulkSupplements powder, NOW Sports/iHerb, Vitacost, and Amazon marketplace; capsule dosing costs more. Updated 2026-05-28.
How much you'd eat to match a supplemental dose.
Foods provide glutamine as part of intact protein; isolated supplement dosing is more concentrated.
What to test, the optimal window inside the conventional range, and how long a response takes.
Glutamine (5 to 20 g per day) modestly raises plasma glutamine; clinical benefit is most clear in critical illness and burn patients.1,8
Routine plasma glutamine in healthy adults is rarely clinically actionable. Functional markers in IBD/IBS: fecal calprotectin, zonulin (controversial).
Where this appears in the symptom-to-supplement map, ranked by relevance.
L-glutamine fuels enterocytes and may support tight junction integrity, which could help maintain normal intestinal permeability.1,16
Often dosed away from meals; use caution in significant hepatic or renal impairment.
Glutamine is the primary fuel for enterocytes and small trials show it can blunt the rise in intestinal permeability triggered by prolonged or heat-stressed exercise.14,16
Tested at roughly 0.25 to 0.9 g per kg taken in the hours before a long effort; this is adjunctive and does not replace a graded gut-training and fueling plan with a sports clinician.
Glutamine is a primary fuel for rapidly dividing immune and gut cells, which can be depleted by surgical stress.15
Most relevant after major or catabolic surgery rather than minor procedures; discuss with your care team if you have liver or kidney concerns.
Glutamine can serve as an alternative brain fuel and some people use it to blunt acute sugar cravings, but controlled data are sparse.1,2
Useful only as an in-the-moment self-experiment for sugar urges; responses vary widely between people.
Glutamine is commonly used for gut-barrier support and post-infectious GI recovery.1,2
Often better tolerated in divided doses.
Glutamine is a primary fuel for enterocytes and may help restore gut barrier integrity in post-infectious IBS-D.1,2
One notable trial showed benefit specifically in post-infectious IBS-D with increased intestinal permeability; less clear for other IBS-D subtypes.
L-glutamine is a primary fuel for enterocytes and may support mucosal repair, though evidence for treating routine diarrhea is limited.1,2
Most relevant when diarrhea relates to mucosal injury; use caution in those with significant liver dysfunction.
L-Glutamine is a brain amino acid that some report helps curb sugar and alcohol cravings, possibly by stabilizing blood sugar and neurotransmitter supply.19,1
Evidence is largely anecdotal; view as a minor supportive measure rather than a treatment and seek professional care for alcohol use disorder.
Glutamine is a primary fuel for intestinal enterocytes and may support repair of the gut lining, though evidence for post-antibiotic recovery specifically is limited.15,1
A reasonable adjunct for mucosal support, not a substitute for probiotics here.
Glutamine fuels immune and gut cells and plasma levels fall after prolonged exercise, but supplementation has not reliably reduced infection rates.17,9
May support gut comfort during heavy training blocks; immune benefit is unproven.
L-glutamine fuels enterocytes and may support mucosal health, with only indirect relevance to general digestive comfort.
Adjunctive at best for this symptom; use caution in significant liver impairment.
Glutamine can be converted to glucose via gluconeogenesis and may help blunt sugar cravings, but data for reactive hypoglycemia are minimal.1,2
Lowest-priority option here; prioritize balanced meals and clinical assessment of recurrent crashes.
Evidence-based stacks that include it, with the exact dose and timing each one uses.
Primary fuel source for enterocytes and studied for gut-barrier biology; human benefit depends on population and clinical context.
L-Glutamine is a primary fuel source for intestinal epithelial cells and may help support gut barrier integrity, with a single randomized trial suggesting benefit in post-infectious, diarrhea-predominant IBS. Evidence is limited to early studies, so any benefit should be considered tentative.1,15
L-Glutamine is a primary fuel for rapidly dividing cells such as fibroblasts, enterocytes, and immune cells, and it can become conditionally essential during the catabolic stress of major surgery or trauma. Most supportive data come from clinical or critically ill populations, so benefit in routine outpatient recovery is less established.1,2
L-Glutamine is an amino acid that can serve as a substrate for glucose production, and some practitioners use it to try to take the edge off acute sugar or carbohydrate cravings. Direct human evidence for craving control is very limited and largely anecdotal, so it is positioned as an optional, experimental support tool.19,1
Glutamine is a substrate for glutathione synthesis (via glutamate). Combined use supports antioxidant capacity in critical illness and gut health.
Recommendation: Combine for gut and oxidative support. Useful in IBD and post-surgical recovery.
Colostrum and L-glutamine are frequently combined for gut barrier support, as both contribute to intestinal mucosal repair and integrity.
Recommendation: Reasonable to combine for gut health. No timing separation needed.
L-glutamine fuels intestinal cells and supports the gut barrier, complementing the way probiotics strengthen the mucosal lining.
Recommendation: Reasonable to combine for gut barrier and digestive support, with no special timing required.
L-glutamine and zinc carnosine are a complementary gut-repair pairing, both promoting integrity and healing of the intestinal and gastric mucosa.
Recommendation: Reasonable to combine for gut barrier support. No timing separation needed; both are commonly taken with or between meals.
L-glutamine and the probiotic yeast Saccharomyces boulardii are often combined for gut barrier and digestive support, acting through complementary mucosal mechanisms.
Recommendation: Reasonable to combine for intestinal support. No timing separation needed.
Psyllium forms a viscous gel that slows gastric emptying and small-bowel transit, which may trap free amino acids and theoretically reduce absorption of L-glutamine when the two are taken together.
Recommendation: Separate L-glutamine and psyllium by at least 2 hours. Take L-glutamine on its own with water, away from your fiber dose.
Numbered references. Citations throughout the page link here.
Meta-analysis of 10 studies (352 participants) found glutamine did not significantly affect intestinal permeability overall, but subgroup analysis showed significant reduction at doses >30g/day.
Glutamine supplementation in burn patients significantly reduced mortality, length of hospital stay, and infection rates compared to standard care.
Yue HY, Wang Y, Zeng J et al.. Enteral glutamine supplements for patients with severe burns: A systematic review and meta-analysis. Chinese journal of traumatology = Zhonghua chuang shang za zhi. 2024
Linden MA, Teixeira TLM, Freitas RGBON et al.. Arginine and glutamine supplementation on transthyretin levels in severely burned patients: A systematic review. Nutrition (Burbank, Los Angeles County, Calif.). 2022
Sun Y, Zhu S, Li S et al.. Glutamine on critical-ill patients: a systematic review and meta-analysis. Annals of palliative medicine. 2021
Cieri-Hutcherson NE, Hutcherson TC, Conway-Habes EE et al.. Systematic Review of l-glutamine for Prevention of Vaso-occlusive Pain Crisis in Patients with Sickle Cell Disease. Pharmacotherapy. 2019
Sayles C, Hickerson SC, Bhat RR et al.. Oral Glutamine in Preventing Treatment-Related Mucositis in Adult Patients With Cancer: A Systematic Review. Nutrition in clinical practice : official publication of the American Society for Parenteral and Enteral Nutrition. 2016
Systematic review and meta-analysis examining glutamine's effects on athletic performance, body composition and immune function across clinical trials.
Oldani M, Sandini M, Nespoli L et al.. Glutamine Supplementation in Intensive Care Patients: A Meta-Analysis of Randomized Clinical Trials. Medicine. 2015
Wischmeyer PE, Dhaliwal R, McCall M et al.. Parenteral glutamine supplementation in critical illness: a systematic review. Critical care (London, England). 2014
Oral glutamine supplements dramatically and safely reduced all major IBS-related endpoints in patients with IBS-D with intestinal hyperpermeability following enteric infection.
Acute oral glutamine consumption attenuated gastrointestinal permeability relative to placebo during exercise in the heat, even at lower doses, in a dose-dependent manner.
Glutamine essential for lymphocyte proliferation, cytokine production, macrophage phagocytosis, and neutrophil bacterial killing; becomes conditionally essential in critical illness.
Glutamine is major nutrient for maintaining intestinal barrier function; depletion results in villus atrophy, decreased tight junction protein expression, and increased intestinal permeability.
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