Glutamine is one of the 20 amino acids. It is a non essential amino acid (i.e. human body can synthesize glutamine on its own) but it becomes essential (need to be provided in diet or supplemented) in certain situations, including intensive athletic training, certain digestive disorders, and injuries. It has been shown to be useful for muscle growth in weightlifting, bodybuilding, endurance, and other sports. It is also known that glutamine has various effects in reducing healing time after operations.