Glutamine is the most plentiful amino acid in your body. Your body makes enough of this protein building block on its own, so it is not an essential amino acid. However, when under extreme stress such as a severe illness, an injury or very heavy exercise, your body might need more glutamine than it can make, according to University of Maryland Medical Center. You’ll most often find glutamine supplements in the form of L-glutamine. Food sources include meats, milk, raw spinach and cabbage. Consult a doctor before supplementing with glutamine.
Glutamine helps your immune system function properly. Your body also needs glutamine for removing one common waste product from your body--excess ammonia. Glutamine appears necessary for normal digestion and brain function as well, according to UMMC.
Glutamine supplements may be helpful when your body is stressed because your body releases cortisol, which can lower your glutamine stores. In the cases of burns, surgeries, injuries, infections and other trauma, glutamine supplements may strengthen your immune system and reduce infections.
Glutamine also may help endurance athletes or overtrained athletes avoid upper respiratory tract infections after strenuous exercise events such as marathons, which is a common occurrence, reports the U.S. Institute of Medicine.
Glutamine is sometimes given to cancer patients who are undergoing radiation therapy or chemotherapy. Initial scientific evidence as of 2010 pointed to glutamine's reducing diarrhea and mouth inflammation associated with chemotherapy, reports UMMC. Glutamine also may help reduce severity of diarrhea in HIV-infected people who take protease inhibitors, according to Dr. Ray Sahelian of Los Angeles.
If you are well-nourished, a glutamine supplement may not do much for you—even if you’re an athlete who trains extremely hard, says M. Gleeson, author of a scientific review for The Journal of Nutrition. The suggested reasons for taking glutamine supplements-- support for your immune system as well as increased glycogen synthesis and a possible anticatabolic, or muscle loss prevention, effect--have little support from well-controlled studies in healthy and properly-nourished people, Gleeson says.
Also, glutamine supplementation does not prevent post-exercise changes in some aspects of your immune function, even when depleted levels of glutamine are boosted to normal levels.
Some theories call for taking glutamine if you have inflammatory bowel disease, according to UMMC, because it helps to protect your gastrointestinal tract lining called the mucosa. However, scientific evidence as of 2010 showed that glutamine supplements did not improve symptoms of conditions like Crohn's disease, according to UMMC.
According to UMMC, more clinical research is needed before the medical community knows whether glutamine supplements are effective or safe to use as part of cancer treatment regimens. Also, the jury is still out on whether glutamine really prevents endurance athletes from catching colds or other illnesses after big events because more valid and verifiable evidence is needed to draw strong conclusions, according to the U.S. Institute of Medicine. The institute also reports that critically ill and burn patients may have a tough time gaining the full immune-boosting benefit from glutamine supplements because their low muscle mass reduces their ability to synthesize glutamine.
Glutamine appears to have no side effects when taken in low doses, notes Sahelian. The side effects for large doses taken over a long time frame are unknown, according to Sahelian.