Glutamine is one of 20 amino acids found in the human body. Amino acids are the basic component of proteins, the compounds that are essential to the formation of muscle and tissue within the body. The function of each protein is determined by its genetic code. Glutamine is classified as a nonessential amino acid, as the body does produce its own glutamine. A combination of carbon, hydrogen, nitrogen, and oxygen atoms, glutamine is the most abundant of the amino acids and it is involved in more human metabolic processes than any other such chemical.
If the body were to become deficient in its own production of glutamine, it is abundant in food sources such as poultry, fish, and beans.
Glutamine contributes to a number of important functions within the body. The most prominent of these actions is the contribution of glutamine to the formation of proteins for muscle and tissue construction, particularly those of the intestinal tract. Glutamine also aids in the formation of the cells of the small intestine, the area where the many important transfers between the digestive process and absorption into the cardiovascular system and organs occur.
Glutamine also is a secondary but meaningful contributor to the reduction of the time required for postoperative healing and repair within the body.
Glutamine has a reputation as a "brain food"—the connection between glutamine and brain function is due to the role it plays in the formation of glutomic acid used by the brain. Glutamine is an important component in the metabolism of nitrogen.
Glutamine plays a key role in the maintenance of the overall health of the immune system, the process by which the body is protected from viruses, and other transmitted dangers to health. When consumed as a dietary or nutritional supplement, glutamine is primarily used by weightlifters and strength sport athletes. It is intended to replenish amino acid stores consumed by the body through intense and repetitive resistance exercise. In a related application, glutamine is occasionally used as a treatment for muscle cramps.
Glutamine is commercially available both as a freestanding supplement in powder form, as well as through its use as an ingredient in multiple purpose supplements. When administered on its own, glutamine is typically taken in quantities of 500 mg. The similarity in names between monosodium glutamate, the flavor enhancer in foods known as MSG, and glutamine often causes confusion; MSG has none of glutamine's chemical properties.
The two fundamental questions posed by athletes concerning any intended nutritional supplement usage are whether the supplement will improve performance, and whether the supplement safe for use. The more determined the athlete is in the pursuit of success, the more often the performance question overrides any concerns regarding the product's safety. Glutamine is a useful supplement in the recovery of amino acid stores that will become depleted after a heavy weight training workout. When an athlete is pursuing the creation of greater body mass, glutamine will aid the process provided that all other components of effective training are in place. Glutamine is a training aid, but it is not a shortcut to a more powerful musculoskeletal frame.
In addition to its amino acid replacement capabilities, the most prominent positive feature of glutamine is the fact that it is nontoxic. Glutamine is also used by endurance athletes to prevent a decrease in the function of the immune system after long endurance-type events such as a marathon. Endurance sports tend to create stresses upon the immune system, and a decreased immune effect is a factor underlying a greater risk of infection in the body arising after the event; such effects are in part counteracted by glutamine supplements. The possible negative consequences of glutamine use are related to the relationship between glutamine ingestion and the possible trigger of a rise in the insulin level within the body. It is for this reason that glutamine supplements are not recommended for persons with kidney or liver disease.
The bodybuilding industry has fostered a number of unsubstantiated claims concerning the muscle-developing qualities of glutamine that are extrapolations of the provable science supporting glutamine role in the restoration of amino acid stores. The most prominent of such claims are the stimulation of human growth hormone production in the pituitary gland, as well as the role of glutamine in the cure of ulcers in the stomach. No scientific evidence exists in support of either of these propositions.
A further concern with the use of glutamine supplements is that of any consumption of a multipurpose supplement that may have a number of compounds used in its formulation that are incompletely described in its packaging. Care must be taken to ensure that the constituent parts of the supplement are all ones that the athlete can consume, and that each component safely interacts with the others.
see also Dietary supplements; Protein supplements; Supplement contamination.