L-Alanyl-Glutamine is a dipeptide composed of the amino acids L-alanine and L-glutamine. Its use to support the small intestine is primarily justified by scientific evidence. Glutamine, in particular, is a key fuel source for enterocytes (cells lining the small intestine) and plays a critical role in maintaining gut barrier function, supporting mucosal integrity, and modulating inflammation. L-Alanyl-Glutamine is more stable in solution than free glutamine, making it a preferred supplement in clinical nutrition, especially for patients at risk for intestinal mucosal atrophy or those with increased intestinal permeability (commonly termed "leaky gut").

Several clinical studies and reviews have demonstrated that supplementation with L-Alanyl-Glutamine can reduce intestinal permeability, improve nutrient absorption, and aid in recovery from intestinal injury, such as that caused by chemotherapy, trauma, or surgery. For example, randomized controlled trials have shown that L-Alanyl-Glutamine supplementation in critically ill patients or those undergoing major abdominal surgery can decrease the incidence of infections and shorten hospital stays, likely due to its protective effects on the gut mucosa.

In summary, the use of L-Alanyl-Glutamine for supporting the small intestine is grounded in scientific research, with moderate to strong evidence supporting its beneficial effects on gut structure and function in both clinical and experimental settings.