Glutamine is the most abundant free amino acid in the body. Amino acids are the building blocks of protein. Glutamine is produced in the muscles and is distributed by the blood to the organs that need it. Glutamine might help gut function, the immune system, and other essential processes in the body, especially in times of stress. It is also important for providing “fuel” (nitrogen and carbon) to many different cells in the body. Glutamine is needed to make other chemicals in the body such as other amino acids and glucose (sugar).