An amino acid integral to the biosynthesis of proteins, glutamine is not considered essential to nutrition, but it is a vital part of maintaining proper nutrition and balance when bodybuilding or weight training. Glutamine is also the most plentiful amino acid in the body, and plays a role in numerous processes within the body, including protein synthesis, regulation of the renal system, and cellular energy. Muscle mass is the principal glutamine-production system of the human body, with roughly 90% of the body’s glutamine produced in muscle tissue alone. The live, brain, and lungs also produce small quantities of glutamine, and the liver is capable of glutamine synthesis as well, though it typically acts more as a regulator than as a producer within the body. Intestinal cells, kidney cells, and active immune cells are the body’s primary consumers of glutamine, and glutamine has shown promising results in reversing both cachexia in autoimmune disease patients, and preventing systemic infection when recovering from surgery.