L-glutamine

L-Glutamine, C₅H₁₀N₂O

Evidence: Moderate

L-glutamine is the most abundant amino acid in the body and the primary fuel for the cells that line your intestine. Those cells turn over rapidly and have an unusually high demand for energy, and glutamine is what they burn first. By supplying this preferred fuel, glutamine supports the upkeep and renewal of the gut lining, the single-cell barrier that manages what passes from the gut into the body.

It is one of the most studied compounds in nutritional science, and a substantial body of research examines its role in intestinal barrier function and integrity. We include it to support the structural side of gut health, complementing the fibres that feed the microbiome.

PubMed indexes over 58,000 peer-reviewed papers on glutamine.

Selected study 1 of 2

Achamrah N, Dechelotte P, Coeffier M. Glutamine and the regulation of intestinal permeability: from bench to bedside. Current Opinion in Clinical Nutrition and Metabolic Care. 2017;20(1):86-91. doi:10.1097/MCO.0000000000000339

Study summary

Study type: Narrative review on glutamine and intestinal barrier function.

Observed benefits: Across models, glutamine supported the architecture of the gut lining, the proteins that seal the barrier, and measures of intestinal integrity.

Mechanisms: As the preferred fuel for intestinal cells, glutamine preserves cellular energy, supports antioxidant defences and helps maintain tight-junction proteins.

Safety: No consistent adverse events reported at usual oral doses.

Evidence strength: Strong mechanistic basis, with human evidence still limited and judged moderate.

Selected study 2 of 2

Kim M, Kim H. The Roles of Glutamine in the Intestine and Its Implication in Intestinal Diseases. International Journal of Molecular Sciences. 2017;18(5):1051. doi:10.3390/ijms18051051

Study summary

Study type: Narrative review pooling roughly 140 studies on intestinal glutamine.

Observed benefits: Glutamine supported the renewal of the gut lining and the proteins that maintain the barrier across experimental models, with a controlled human trial reporting improved measures of intestinal permeability.

Mechanisms: Glutamine supports growth-factor signalling and tight-junction proteins and tempers pro-inflammatory pathways.

Safety: Generally regarded as safe at clinical doses up to about 15 g/day.

Evidence strength: Robust mechanistic and pre-clinical data, with smaller human trials; clinical support judged moderate.