Glutamine and Pediatric Intestinal Barrier Function: A Scoping Review of Clinical Evidence and Research Gaps

Background/Objectives: Glutamine has been proposed as a nutritional modulator of intestinal epithelial integrity, but its effects on intestinal barrier function in children remain uncertain. This scoping review mapped the available human evidence on glutamine in relation to pediatric intestinal permeability, mucosal injury, microbial translocation, and intestinal adaptation. Methods: The review followed Joanna Briggs Institute methodology and PRISMA-ScR guidance. PubMed, Scopus, and Web of Science Core Collection were searched. Eligible studies included participants aged <18 years and assessed glutamine supplementation or endogenous glutamine status in relation to predefined barrier-related outcomes. Data were charted using a standardized form and synthesized descriptively according to clinical population, study design, glutamine exposure, and barrier domain. Results: Of 598 records identified, 434 unique records were screened. Eighteen publications representing 15 distinct or partially overlapping studies/cohorts were included. Functional intestinal permeability was the most frequently investigated domain. Findings were heterogeneous, with favorable, partial, transient, and null effects reported across different pediatric populations. Evidence for microbial translocation was limited and showed no clear benefit. Positive findings related to intestinal adaptation were mainly derived from uncontrolled or combined interventions, limiting attribution to glutamine. Direct mechanistic evidence in children was sparse, and no consistent major safety signal emerged, although the available safety evidence was limited. Conclusions: Current evidence does not support a uniform beneficial effect of glutamine on pediatric intestinal barrier function. Observed effects vary across populations, intervention characteristics, and outcome assessment methods.