Glutamine

Evidence ratingLow

The most abundant non-essential amino acid in the body. Plays a key role in maintaining intestinal barrier integrity and fueling immune cells. While blood glutamine drops after intense exercise, multiple RCTs have not confirmed benefits for muscle strength, hypertrophy, or performance in healthy individuals.

An ingredient with still-limited research

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Effects reported in research

Support for intestinal barrier function (research on gut protection during intense exercise and post-surgery)

Mitigation of temporary immune suppression after intense training (limited evidence)

Suggested positive effects on gut microbiome (still under investigation)

Dosage & timing

Research uses 5–20 g/day.
Often taken post-workout or before bed.
Additional benefit is limited when adequate dietary protein is consumed.

Cautions

•Generally safe at typical doses.
•Consult a doctor with kidney or liver disease.
•Caution may be warranted in some neurological conditions due to conversion to glutamate.

Supporting research

Review

Glutamine supplementation in sport and exercise: A review in the field of immunology and cell biology

Nutrients, 2018

A review of glutamine supplementation in athletes and adults performing intense exercise, from an immunology and cell-biology standpoint. It notes that plasma glutamine falls after intense exercise (linked to transient immune suppression) and that glutamine helps maintain gut barrier function, while additional benefits are limited when protein intake is adequate. Direct strength or hypertrophy benefits are not confirmed across multiple RCTs.

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Last checked: 2026-06-23