Glutamine is a conditionally essential amino acid used by the body in the synthesis of protein. Under normal conditions, the body has ample glutamine to perform its required processes, as it is the most abundant amino acid in the body; however, during times of extreme stress (i.e. during exercise) the body simply can’t produce enough to meet demand -- this is what makes it therefore “conditionally” essential.
Glutamine is involved in a number of processes in the body, none more prominent than ridding the body of excess ammonia (a common metabolic waste product. It also bolsters immune system function, digestion, and even normal brain function. Some other research even indicates that glutamine supplementation may increase Human Growth Hormone (GH) levels, which in turn metabolizes body fat and encourages new muscle growth.
The most common reason Glutamine is often supplemented, though, is for its perceived ability to enhance recovery and decrease soreness following intense training sessions. Specifically, glutamine is believed to prevent muscle wasting by keeping the body in an anti-catabolic state, this is especially important during fat loss dieting phases when maintaining muscle is of the highest priority.