Glutamine as the preferred fuel for gut lining cells
Enterocytes, the cells lining the small intestine, use glutamine as a primary energy source rather than relying mainly on glucose. This high local demand is why much of an oral glutamine dose is consumed by the gut itself. The amino acid also feeds pathways that support the cells maintaining the intestinal barrier.
Its role in the gut is mechanistically clearer than its disputed role in muscle building.
Where supplementation may support the barrier
Research suggests glutamine can help maintain tight-junction proteins, the seals between gut cells, especially under physiological stress such as critical illness, intense endurance exercise, or injury where glutamine demand outstrips supply. In healthy, well-nourished people the added benefit is less clear because pools are already sufficient.
This is general educational information, not medical advice. It is not a treatment for any digestive disease. Consult a qualified professional before using glutamine for gut symptoms.