The amino acid L-glutamine plays a key role in the proper functioning of the immune system, intestines and brain. It makes up about 60% of the body’s total reservoir of amino acids and has the highest concentration in the blood. L-glutamine regulates the transport of nitrogen to and from the muscles, promoting the balance of amino acids in the body. Although L-glutamine, because it is endogenously synthesized, is considered a non-essential amino acid, it becomes essential and necessary in periods of intense physical activity as well as in other cases of intense metabolic stress. Under these conditions plasma glutamine levels are reduced and needs may need to be met.