• Take care not to confuse glutamine with substances that have similar-sounding names, such as glutathione, glutamic acid, gluten, and monosodium glutamate.
Glutamine is a nonessential amino acid. "Nonessential" means that the body can create its own supply if the diet is lacking in glutamine-rich sources, such as poultry, fish, and legumes. Few people who are basically healthy and follow a balanced diet are deficient in this amino acid, one of the most abundant in the bloodstream. But there are some important exceptions.
Glutamine is primarily produced in the muscles and appears to play an important part in keeping them functioning normally. It's also used by white blood cells and contributes to normal immune-system function. Individuals with muscle-wasting and immune-system related illnesses (such as cancer or AIDS) who may be incapable of manufacturing their own supply of glutamine, may benefit from glutamine supplementats taken along with other amino acids.
Several studies have shown that glutamine, when used as an oral rinse, can help to reduce cancer chemotherapy-induced mouth sores. Whether glutamine taken orally can aid in preventing other complications of cancer treatment, including stomach irritation, is still being examined. In fact, some research indicates it may stimulate the growth of certain tumors.
One of glutamine's most important tasks in the body is to nourish cells that line the intestine and stomach. Preliminary studies have shown that supplements of glutamine may protect against aspirin-induced gastric lesions and enhance healing of painful peptic ulcers. It has also been examined for preventing stress ulcers in individuals treated for severe burns. Those with stomach problems associated with Crohn's disease and ulcerative colitis may theoretically benefit from glutamine too.
Glutamine passes freely across the blood-brain barrier. Once in the brain, it's converted to glutamic acid and increases the concentration of GABA (gamma-aminobutyric acid). Both glutamic acid and GABA are essential for proper mental function. Because of its action in the brain, glutamine supplements have been recommended for preventing the deleterious effects of alcohol on the brain and for reducing alcohol cravings—a finding that has support in clinical trials. Some sources describe glutamine as a "brain fuel" capable of stimulaing mental alertness and clear thinking. This use is still unproven.
Glutamine has also been tried, with mixed results, for treating weight loss, insomnia, depression, anxiety, and schizophrenia.
Look for glutamine supplements prefaced by the letter L. This form resembles the glutamine in the body more than supplements prefaced by the letter D.
• Methotrexate, a drug used to treat certain kinds of cancer, psoriasis, and rheumatoid arthritis, may interefere with glutamine's effectiveness in treating mouth ulcers resulting from cancer chemotherapy.
• There are no other known drug or nutrient interactions associated with glutamine.
• Some people may experience headaches and other side effects with glutamine, but much remains to be learned about the potential adverse reactions associated with this supplement. In clinical trials, no toxic reactions were recorded at relatively high doses of 4 to 21 g a day.
• If you have any serious illness or are pregnant or breast-feeding, only take an amino acid such as glutamine after consulting your doctor.
• To be safe, never take glutamine--or any single amino acid for that matter--for longer than three months unless you are under the direction of a doctor familiar with its use.