Glutamine is conditionally essential amino acid because it can be manufactured in the body, but under extreme physical stress the demand for glutamine exceeds the body's ability to make it. Adequate amounts of glutamine are generally obtained through diet alone because the body is also able to make glutamine on its own. Certain medical conditions, including injuries, surgery, infections, and prolonged stress, can deplete glutamine levels. Since glutamine plays a key role in the immune system, a deficiency in this nutrient can significantly slow the healing process.