Glutamine is the most abundant amino acid (building block of protein) in the bloodstream. It is considered a "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. Most glutamine in the body is stored in muscles followed by the lungs, where much of the glutamine is manufactured. Glutamine is important for removing excess ammonia (a common waste product in the body). In the process of picking up ammonia, glutamine donates it when needed to make other amino acids, as well as sugar, and the antioxidant glutathione.

Several types of important immune cells rely on glutamine for energy. Without glutamine, the immune system would not function appropriately. Glutamine also appears to be necessary for normal brain function and digestion.

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, however. In these cases, glutamine supplementation may be helpful.

Wound healing

When the body is stressed (such as from injuries, infections, burns, trauma, or surgical procedures), steroid hormones, such as cortisol, are released into the bloodstream. Elevated cortisol levels can deplete glutamine stores in the body. Since glutamine plays a key role in the immune system, a deficiency in this nutrient can significantly slow the healing process. Clinical studies have reported that glutamine supplements enhance the immune system and reduce infections (particularly infections associated with surgery). Glutamine supplements may also aid in the recovery of severe burns.

Inflammatory bowel disease (IBD)

Glutamine helps to protect the lining of the gastrointestinal tract known as the mucosa. Because of this, some experts speculate that glutamine deficiency may play a role in the development of inflammatory bowel disease (IBD), namely ulcerative colitis and Crohn's disease. These conditions are characterized by damage to the lining of the small or large intestines, which leads to inflammation, infection, and ulcerations (holes). In fact, some preliminary clinical research suggests that glutamine may be a valuable supplement during treatment of IBD because it promotes healing of the cells in the intestines and improves diarrhea associated with IBD. Not all clinical studies have found this positive benefit, however. For this reason, more research is needed before conclusions can be drawn. In the meantime, follow the advice of your health care provider when deciding whether to use glutamine for IBD.

HIV/AIDS

Individuals with advanced stages of human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) often experience severe weight loss (particularly loss of muscle mass). A few studies of individuals with HIV and AIDS have demonstrated that glutamine supplementation, along with other important nutrients including vitamins C and E, beta-carotene, selenium, and N-acetylcysteine, may reduce the severe weight loss associated with these conditions.

Obesity

Results from animal studies suggest that glutamine may help suppress appetite. Large-scale research clinical trials of humans would be needed to determine if glutamine supplements are useful in treating obesity in people.

Peritonitis

Glutamine supplementation has long been known to maintain the health of the mucosa (inner lining) of the gastrointestinal tract and inhibit muscle wasting in critically ill patients. Keeping the intestinal mucosa healthy helps prevent infections such as peritonitis (inflammation of the peritoneum, the thin membrane that lines the abdominal wall and covers most of the organs of the body).

Animal studies indicate that a diet supplemented with glutamine may protect the lining of the intestine, inhibit the growth of bacteria, and improve survival rates in animals with peritonitis.

Additional clinical studies of people at high risk for peritonitis infection suggest that diets high in the amino acids glutamine and arginine along with omega-3 fatty acids may lower the risk of infection by more than 50% and significantly shorten the length of hospital stay. These results are somewhat controversial, however, as the way that these supplements appear to work involves an inflammatory response in the peritoneum -- a reaction known to cause peritonitis.

In a hospital setting, a doctor will determine if glutamine supplementation (generally given intravenously) is necessary in someone who is critically ill, particularly following surgery or trauma. This would be used, in part, to prevent or treat peritonitis.

Athletes

Athletes who train excessively may deplete their glutamine stores. This is because they are overusing their skeletal muscles, where much of the glutamine in the body is stored. Athletes who overstress their muscles (without adequate time for recovery between workouts) may have lowered immunity and may be at increased risk for infection or slow recovery from injuries. This is also true for people who participate in prolonged exercise, such as ultra-marathon runners. For this select group of athletes, glutamine supplementation may be useful. This is not true, however, for most exercisers who tend to work out at a much more moderate intensity.

Cancer

Many people with cancer have abnormally low levels of glutamine. For this reason, some experts speculate that glutamine may prove to be a good addition to conventional treatment of cancer under certain conditions. In fact, nutritional support with supplemental glutamine is often used in malnourished cancer patients undergoing chemotherapy or radiation treatments and sometimes used in patients undergoing bone marrow transplants.

Glutamine is used to protect the lining of the small and large intestines from damage caused by chemotherapy or radiation. Glutamine may also protect against the development of mucositis (breakdown of the mucosal membranes of the mouth and nasal passages) caused by therapy for head and neck cancer.

There is some question, however, about whether protection of the intestinal mucosa is a desired result for colon cancer. Plus, some clinical studies suggest that this nutrient may actually stimulate the growth of some tumors. Therefore, more clinical research is needed to know whether use of glutamine is safe or effective to use as part of the treatment regimen for cancer.

Other

Glutamine can aid in healing stomach ulcers and prevent inflammation of the stomach that is caused by chronic use of nonsteroidal anti-inflammatory medications (NSAIDS), including ibuprofen (Advil or Motrin).

Due to its ability to support proper functioning of the digestive tract, glutamine is often used to counteract unexplained weight loss, sub-clinical protein deficiencies, and wasting syndromes which accompany such diseases as cancer (see “Possible Interactions” below), anorexia, and AIDS.

Dietary sources of glutamine include plant and animal proteins such as beef, pork and poultry, milk, yogurt, ricotta cheese, cottage cheese, raw spinach, raw parsley, and cabbage.

Glutamine, usually in the form of L-glutamine, is available as an individual supplement or as part of a protein supplement. These come in powder, capsule, tablet, or liquid form.

Standard preparations are typically available in 500 mg tablets or capsules.

Glutamine should be taken with cold or room temperature foods or liquids. It should not be added to hot beverages because heat destroys glutamine.

Pediatric

For children 10 years and younger: If laboratory tests reveal that a child has an amino acid imbalance that requires treatment, a health care provider may recommend a complete amino acid supplement that contains glutamine.

For children 10 - 18 years: Doses of 500 mg, 1 - 3 times daily, are generally considered safe.

Adult

For adults ages 18 and older: Doses of 500, 1 - 3 times daily, are generally considered safe. Doses as high as 5,000 - 15,000 mg daily (in divided doses) may be prescribed by a health care provider.

As an oral rinse: Place 16 gm (one tablespoonful) of glutamine powder in 240 ml (8 ounces) normal saline or sterile water and mix. Then, swish 30 - 60 ml (1 - 2 ounces) and expectorate, 4 times a day, for radiation therapy-induced mucositis and chemotherapy-induced stomatitis.

Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable health care provider.

Glutamine powder should not be added to hot beverages because heat destroys this amino acid. Glutamine supplements should also be kept in a dry location. Moisture leads to breakdown of this substance.

People with kidney disease, liver disease, or Reye syndrome (a rare, sometimes fatal disease of childhood that is generally associated with use of aspirin in conjunction with chickenpox or an upper respiratory illness) should not take glutamine.

Many elderly people have decreased kidney function and may need to reduce the dose of glutamine.

Glutamine is different from glutamate (glutamic acid), monosodium glutamate, and gluten. Glutamine should not cause symptoms (headaches, facial pressure, tingling, or burning sensation) associated with sensitivity to monosodium glutamate. People who are gluten sensitive can use glutamine without problems.

If you are currently being treated with any of the following medications, you should not use glutamine supplements without first talking to your health care provider.

Cancer Therapy -- Glutamine may increase the effectiveness and reduce the side effects of chemotherapy treatments with doxorubicin, methotrexate, and 5-fluorouracil in people with colon cancer. Similarly, preliminary clinical studies suggest that glutamine supplements may prevent nerve damage associated with a medication called paclitaxel, used for breast and other types of cancers.

However, laboratory studies suggest that glutamine may actually stimulate growth of tumors. Much more research is needed before it is known whether it is safe to use glutamine if you have cancer.

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