Glutamine is one of the twenty amino acids or building blocks that make up proteins.
In the human body, glutamine is the most abundant free amino acid. It is considered a conditionally essential amino acid. Essential amino acids are those that cannot be produced by the body and must therefore be consumed in the diet. A conditionally essential amino acid is one that may stop being produced by the body in specific disease conditions such as prematurity or severe catabolic distress.
Glutamine plays several important roles in the function of the body. Some of the important functions of glutamine include:
- Synthesis of protein, as with all amino acids
- Production of ammonium to help maintaining the kidney’s acid-base balance
- A source of cellular energy
- Donation of carbon to refill the citric acid cycle
Glutamine is produced from glutamate and ammonia by the enzyme glutamine synthetase. It is mainly produced in the muscles, which account for around 90% of all the glutamine synthesized. Glutamine is also released by the brain and lungs in small amounts. The metabolism of glutamine is regulated by the liver, which takes up large amounts of glutamine from the gut.
Glutamine has been a popular subject of research over the last couple of decades and studies have shown it to be beneficial for treating burns, trauma, injury and some side effects of cancer treatment. Glutamine is marketed by several manufacturers as a nutritional supplement because of its role in protein synthesis and energy donation. It is taken as a muscle growth enhancer by body builders, weightlifters and other athletes. Claims also exist that glutamine can raise the level of growth hormone by stimulating its release from the anterior pituitary gland.
In cases of long-term illness or injury, the amount of glutamine in the body is depleted and therefore needs to be supplemented in the diet.