For Patients & Caregivers
Glutamine combined with other nutrients can prevent muscle wasting and weight loss in patients with advanced cancer and HIV, but more research is needed.
Glutamine is the most abundant amino acid in the human body. It is synthesized by most body tissues and is also found in foods such as wheat, corn, barley, peanuts, soybeans, and milk. Glutamine is essential for several bodily processes, and when patients are suffering from states in which the body is malnourished or breaking down its own muscle protein (a state called cachexia), taking extra glutamine can help replenish depleted body levels and prevent adverse health effects. For example, glutamine is the major fuel source of the cells that line the intestinal tract, and is therefore important in maintaining GI function. It is also the major fuel source for lymphocytes and macrophages, which are a vital part of the body’s immune defense. It acts both as a precursor for protein synthesis and a means by which excess toxic ammonia can be eliminated from the body. Finally, glutamine is important in the synthesis of glutathione, a molecule that helps detoxify foreign substances in the liver.
Glutamine may help treat cachexia (muscle wasting) in patients with advanced cancer and AIDS.
- To prevent nutritional problems in alcoholism
No scientific evidence supports this use.
- To prevent cachexia (muscle wasting) in advanced cancer and AIDS
Preliminary results from clinical trials show that a combination of glutamine, arginine, and beta-hydroxy-beta-methylbutyrate (Juven®) can promote weight gain in these patients, but the long-term effectiveness is not known.
- To reduce chemotherapy-induced gastrointestinal toxicity
One study showed that glutamine given intravenously to patients receiving chemotherapy for gastric or colorectal cancer significantly reduced nausea, vomiting, and diarrhea.
- To improve tissue integrity
Clinical research supports the use of intravenous glutamine to enhance the integrity of the intestine in critically ill patients.
- To stimulate the immune system
Although glutamine is a necessary fuel source for lymphocytes (a type of immune cell), there is no solid evidence that glutamine supplements can stimulate the immune system in healthy people. Intravenous glutamine has been shown to help improve the immune status, prevent infection, and help prevent depletion of intestinal immune cells in critically ill patients and patients recovering from surgery.
- To treat peptic ulcers
No scientific evidence supports this use.
- Intravenously, to improve recovery from surgery
Several clinical trials support this use.
- To improve recovery from intense exercise
Blood glutamine levels have been found to fall after intense exercise, but several studies have concluded that supplementation with glutamine does not improve recovery from exercise or prevent exercise-related immune suppression or infection.
For Healthcare Professionals
The most abundant amino acid synthesized by most body tissues and also absorbed from food sources, glutamine is the major fuel source of enterocytes, lymphocytes, and macrophages, and is thought to act by enhancing gut integrity, immune function, and protein synthesis (1) (2). Patients take the supplemental form to treat cancer and HIV/AIDS related cachexia or recovery from catabolic states such as surgery, sepsis, and intense exercise.
Data from several clinical trials indicate that parenteral or enteral free glutamine or glutamine-containing dipeptides improve nitrogen balance, preserve intestinal integrity, maintain intracellular glutamine levels, and reduce hospital stay in post-surgical or critically ill patients (7) (8) (9). A meta-analysis showed benefits of supplementation in patients with acute pancreatitis who receive total parenteral nutrition (25). However, supplementation may not be effective in decreasing sepsis in surgical infants with gastrointestinal disease (20); a systematic review failed to find sufficient data to support use in young infants with severe gastrointestinal disease (21).
Glutamine was shown to prevent genotoxic and clastogenic damages caused by cisplatin in mice (26). Pilot studies suggest its effectiveness in treating HIV- and cancer-related cachexia when used in combination with beta-hydroxy-beta-methylbutyrate (HMB) and arginine (3) (4) (5). The oral form was shown useful in preventing oxaliplatin-induced neuropathy in colorectal cancer patients (6); in reducing chemotherapy-induced mucositis (12) (18) (27) (28) and gastrointestinal toxicity (19); and may be effective against radiation morbidity in breast cancer patients (23). Intravenous glutamine significantly reduced chemotherapy-induced nausea, vomiting, and diarrhea in patients with gastric or colorectal cancer (10). Conclusions from a meta analysis indicate benefits in reducing the duration, but not severity of diarrhea (22). However, conflicting data indicate that perioperative glutamine did not have an influence on post-surgical complications or infection in gastrointestinal cancer patients (11). Furthermore, recent findings suggest a role in tumor cell growth and maintenance (17) (24). More research is needed to resolve the ambiguity.
Glutamine is the major fuel source of enterocytes and is therefore essential for the maintenance of intestinal mucosal integrity and function (1). It also maintains immune function by serving as the principle metabolic fuel for lymphocytes and macrophages, and acts as a precursor for protein synthesis and, with cysteine and glycine, is involved in glutathione (GSH) synthesis. Intravenous glutamine preserves liver and intestinal glutathione stores in animal models of oxidant damage. Glutamine is also involved in nitrogen exchange, as it neutralizes and eliminates excess ammonia formed during protein catabolism. As a nitrogen donor, it contributes to the synthesis of other non-essential amino acids, including the purines and pyrimidines, and is therefore essential for the proliferation of most cells (15). It also plays a supportive role during biochemical stress and sepsis. Although the mechanism in treatment of cachexia is unclear, it is thought that glutamine, a modulator of protein turnover, enhances net protein synthesis (3). Clinical evidence suggests that total parenteral nutrition supplemented with glutamine improves nitrogen balance, maintains the intracellular glutamine pool, enhances protein synthesis, and prevents deterioration of gut permeability in post-surgery patients (4).
Glutamine may potentiate the tumoricidal effect of methotrexate (MTX) since polyglutamation of MTX impairs its efflux from tumor cells and may reduce its accumulation in the gut. Rats fed a glutamine-enriched diet while receiving MTX chemotherapy exhibit less enterocolitis, improved hematologic parameters, decreased sepsis, and improved survival (16). The supplemental intravenous form leads to increases of GSH in the gut, but not in tumors, in a sarcoma-bearing rat model.
However, recent findings show that glutamine transporters are upregulated in tumor cells and that glutamine acts as a mitochondrial substrate and promotes protein translation. This indicates tumor cell dependence for growth and maintenance (17). And a recent study demonstrated that glutamine helps cancer cells survive acidic stress, rather than provide nutrition, through enzymatic deamidation (24).