Glutamine
No evidence it helps muscle or performance; the sources don't support taking it
What it is
The most abundant amino acid in muscle and blood. The body makes it itself, and an adult gets about 3–6 g a day from protein-containing foods.
Benefits
No scientific evidence shows that glutamine increases lean body mass or muscular performance (ISSN). In weightlifters it changed neither strength nor body composition. In another, of 16 people, it reduced strength loss and muscle soreness after exercise. Research offers little support for protection from upper respiratory tract infections (NIH).
Dose
There is no recommended dose: ISSN puts glutamine among supplements with little to no evidence of efficacy and does not support taking them. The study that found no effect on strength used almost 45 g a day (NIH).
When to take it
The sources give no advice on timing.
Who it's for
The sources name no group of people who train and need glutamine. In medicine, seriously ill patients, for example with infections, intestinal diseases or burns, take it safely as part of their care (NIH).
Who can skip it
People hoping for muscle growth or better results: research to date does not support taking glutamine alone to improve athletic performance (NIH).
Forms
Free L-glutamine and the dipeptide L-alanyl-L-glutamine are sold. According to a 2019 review, the dipeptide raised glutamine in plasma, muscle and liver more effectively than free glutamine and is more stable in solution. These are data on glutamine levels, not on sports performance; that passage of the review does not say in whom they were obtained.
Safety
No side effects were reported in the studies, and no safety concerns were reported at about 45 g a day for 6 weeks (NIH). The sources give no tolerable upper level.
This is a summary of public sources, not medical advice. If you have a health condition, are pregnant or take medication, talk to a doctor before taking a supplement.
Sources
- Dietary Supplements for Exercise and Athletic Performance — Fact Sheet for Health Professionals . NIH Office of Dietary Supplements, 2024.
- ISSN exercise & sports nutrition review update: research & recommendations . International Society of Sports Nutrition, 2018.
- Glutamine as an Anti-Fatigue Amino Acid in Sports Nutrition . Nutrients, 2019.
Other supplements
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