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Research · Supplements

Glutamine

A meta-analysis of 25 trials in athletes found no effect of glutamine on aerobic performance, lean mass or immune cell counts. One crossover trial reported less soreness. Pooled trials found no change in gut permeability overall. In critically ill patients with organ failure, high-dose glutamine was linked to higher mortality in one trial. Pooled IV trials found no difference.

Add to Bio HackChecked 2026-11-09
Status
Dietary supplement in the US. L-glutamine oral powder is also an FDA-approved prescription drug (Endari, NDA 208587) to reduce acute complications of sickle cell disease.
Also called
L-glutamine, glutamine powder, alanyl-glutamine, glutamine dipeptide, Sustamine, GLN
Taken for
muscle recovery, less soreness, muscle gain, immune support, gut health, leaky gut, preventing overtraining

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help1

Reported risks2

What people take it for, and what was found

Shown to help1

Limited

Muscle soreness and strength recovery

One small trial found lower soreness and faster strength recovery over 72 hours after eccentric exercise in young adults.

The numbers and sources
Effect
In 16 young adults doing eccentric knee extensions, 0.3 g per kg a day for 72 hours gave lower soreness at 24 hours (2.8 against 3.4), 48 hours (2.6 against 3.9) and 72 hours (1.7 against 2.9), and higher fast-speed peak torque at 72 hours (91% against 86% of baseline) [2].
Population
8 women and 8 men, crossover design [2].
Sources
[2]
Caveats
One small trial in one muscle group. No meta-analysis of glutamine and soreness was located.

Not shown to help3

Moderate

Athletic performance and body composition

Not shown to change lean mass, body fat or VO2max in athletes. Body weight fell about 1.4 kg.

The numbers and sources
Effect
Across 25 trials in athletes over 18, glutamine did not change lean body mass, body fat percentage or VO2max. Body weight fell by 1.36 kg (95% CI -2.55 to -0.16) [1].
Population
Athletes, 47 studies reviewed and 25 pooled [1].
Sources
[1]
Caveats
One meta-analysis. The weight change is not explained by a lean mass or fat change in the same analysis [1].
Moderate

Immune function in athletes

Not shown to change lymphocyte or leukocyte counts in athletes.

The numbers and sources
Effect
Glutamine did not change lymphocyte or leukocyte counts. Neutrophils fell at doses above 200 mg per kg (WMD -605.77), and glutamine dipeptide raised post-exercise blood glucose by 0.51 mmol/L [1].
Population
Athletes [1].
Sources
[1]
Caveats
Cell counts are not infection rates. The neutrophil confidence interval as printed (-1200.0 to 52.1) crosses zero, which conflicts with its reported p-value of 0.03 [1].
Moderate

Gut permeability

Not shown to change gut permeability in adults with various diseases. A subgroup taking more than 30 g a day showed a reduction.

The numbers and sources
Effect
Across 10 RCTs (352 participants, mean age 46.5, mixed health conditions), glutamine did not change intestinal permeability (WMD -0.00, 95% CI -0.04 to 0.03). A subgroup above 30 g a day showed a reduction [3]. In 10 men running 60 minutes at 30°C, 0.25 to 0.9 g per kg of fat-free mass 2 hours before lowered a permeability marker; GI symptoms did not change [4].
Population
Adults with various diseases [3]; recreationally active men in heat [4].
Sources
[3], [4]
Caveats
The meta-analysis abstract gives the subgroup dose as both 30 g and 30 mg a day, and its confidence interval (-0.10 to -0.08) does not contain its estimate (-0.01) [3]. A lab marker change without a symptom change [4].

Doses studied

The soreness trial used 0.3 g per kg a day for 3 days [2]. The heat trial used single doses of 0.25, 0.5 and 0.9 g per kg of fat-free mass 2 hours before running [4]. Immune effects on neutrophils appeared above 200 mg per kg [1]. A gut permeability subgroup used more than 30 g a day [3].

Risks

Reported risks1

LimitedHow often is not known

Kidney markers

One small trial found estimated GFR fell 13.3% on high-dose glutamine against 2.9% on control over 14 days in older adults.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
In a crossover RCT of 30 adults (mean age 69) given 0.5 g per kg a day for 14 days, estimated GFR fell 13.3% on glutamine against 2.9% on a casein control, with small rises in urea nitrogen and creatinine; no adverse clinical effects were seen [7]. A review of kidney safety in athletes found 5 glutamine studies; short-term (20 to 30 g within a few hours) and 2-week (0.1 g per kg four times a day) use showed no significant adverse effects in healthy athletes, while the review notes glomerulosclerosis and raised creatinine reported in the setting of diabetic kidney disease [8].
Population
Older care-home residents [7]; athletes and bodybuilders [8].
Sources
[7], [8]
Caveats
The authors of [7] describe the eGFR drop as below their 25% threshold for biological significance. Reference [8] is a narrative review of few studies.

Mixed results1

LimitedHow often is not known

Higher mortality in critically ill patients

One trial found 28-day deaths of 32.4% against 27.2% with high-dose glutamine in ventilated ICU patients. A review of IV trials found no difference.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
In 1,223 ventilated ICU patients with multiorgan failure, 28-day mortality was 32.4% with glutamine against 27.2% without (adjusted OR 1.28, 95% CI 1.00 to 1.64, p = 0.05). In-hospital and 6-month mortality were significantly higher with glutamine [5].
Population
Critically ill adults in 40 ICUs, given glutamine intravenously and enterally [5]. 1,593 critically ill adults in 10 RCTs of IV glutamine [6].
Sources
[5], [6]
Caveats
High doses by vein and tube in people with organ failure. This does not test oral supplement use in healthy people. A 2026 meta-analysis of 10 IV glutamine trials found overall mortality did not differ from standard care (RR 0.93, 95% CI 0.77 to 1.13), while ICU and hospital stays were longer with glutamine [6].

Claims tested and not found

  1. That glutamine builds muscle. Lean body mass did not change across 25 trials in athletes [1].
  2. That glutamine boosts athlete immunity. Lymphocyte and leukocyte counts did not change in pooled trials [1].
  3. That glutamine heals a leaky gut in general. Permeability did not change overall across 10 RCTs [3].

Sources

  1. Ramezani Ahmadi A, Rayyani E, Bahreini M, et al. The effect of glutamine supplementation on athletic performance, body composition, and immune function: A systematic review and a meta-analysis of clinical trials. Clinical Nutrition. 2019. https://doi.org/10.1016/j.clnu.2018.05.001
  2. Legault Z, Bagnall N, Kimmerly DS. The Influence of Oral L-Glutamine Supplementation on Muscle Strength Recovery and Soreness Following Unilateral Knee Extension Eccentric Exercise. International Journal of Sport Nutrition and Exercise Metabolism. 2015. https://doi.org/10.1123/ijsnem.2014-0209
  3. Abbasi F, Haghighat Lari MM, Khosravi GR, et al. A systematic review and meta-analysis of clinical trials on the effects of glutamine supplementation on gut permeability in adults. Amino Acids. 2024. https://doi.org/10.1007/s00726-024-03420-7
  4. Pugh JN, Sage S, Hutson M, et al. Glutamine supplementation reduces markers of intestinal permeability during running in the heat in a dose-dependent manner. European Journal of Applied Physiology. 2017. https://doi.org/10.1007/s00421-017-3744-4
  5. Heyland D, Muscedere J, Wischmeyer PE, et al. A Randomized Trial of Glutamine and Antioxidants in Critically Ill Patients. New England Journal of Medicine. 2013. https://doi.org/10.1056/nejmoa1212722
  6. Lee JG, Kwon IG, Baik SM. The effects of intravenous glutamine supplementation in critically ill patients: a systematic review and meta-analysis. Acute and Critical Care. 2026. https://doi.org/10.4266/acc.002132
  7. Galera SC, Fechine F, Teixeira MJ, et al. The safety of oral use of l-glutamine in middle-aged and elderly individuals. Nutrition. 2010. https://doi.org/10.1016/j.nut.2009.05.013
  8. Davani-Davari D, Karimzadeh I, Sagheb MM, et al. The Renal Safety of L-Carnitine, L-Arginine, and Glutamine in Athletes and Bodybuilders. Journal of Renal Nutrition. 2019. https://doi.org/10.1053/j.jrn.2018.08.014

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