Glutamine is an amino acid that has been studied for its potential role in supporting intestinal health, specifically in relation to what is sometimes called "Leaky Gut Syndrome"—a condition characterized by increased intestinal permeability. Scientific evidence, primarily from in vitro studies, animal models, and clinical trials in critically ill or hospitalized patients (such as those with short bowel syndrome or undergoing chemotherapy), suggests that glutamine is important for the maintenance and repair of the intestinal mucosal barrier. Glutamine serves as a primary fuel source for enterocytes (intestinal cells), and supplementation has been shown to help maintain tight junction integrity and reduce permeability in some experimental contexts. However, direct evidence from high-quality, large-scale clinical trials in otherwise healthy individuals or those specifically diagnosed with "Leaky Gut Syndrome" is limited. The syndrome itself is not universally recognized as a distinct medical diagnosis within mainstream medicine, which complicates the interpretation of data. Nevertheless, small human studies and considerable mechanistic research provide a rationale for glutamine’s potential benefit in supporting gut barrier function. The overall evidence for its use in "Leaky Gut Syndrome" is moderate but not conclusive, warranting a rating of 3 out of 5.