An amino acid integral to the biosynthesis of proteins, glutamine is a vital part of maintaining proper nutrition and balance when bodybuilding or weight training. Glutamine is the most plentiful amino acid in the body, and plays a role in numerous processes, 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% produced in muscle tissue alone. The liver, brain, and lungs also produce small quantities of glutamine, though the liver typically acts more as a regulator than as a producer. 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.