Glutamine

Glutamine, or L-glutamine, is an amino acid derived from another amino acid, glutamic acid. Glutamine plays a role in the health of the immune system, digestive tract, and muscle cells, as well as other bodily functions. It appears to serve as a fuel for the cells that line the intestines. Heavy exercise, infection, surgery, and trauma can deplete the bodys glutamine reserves, particularly in muscle cells. The fact that glutamine does so many good things in the body has led people to try glutamine supplements as a treatment for various conditions, including preventing the infections that often follow endurance exercise, reducing symptoms of overtraining syndrome, improving nutrition in critical illness, alleviating allergies, and treating digestive problems.

There is no daily requirement for glutamine, because the body can make its own supply. As mentioned earlier, various severe stresses may result in a temporary glutamine deficiency. High-protein foods such as meat, fish, beans, and dairy products are excellent sources of glutamine.

Therapeutic dosages of glutamine range from 1.5 to 6 g daily, divided into several separate doses.

Endurance athletes frequently catch an infectious illness after completing a marathon or similar forms of exercise. Preliminary evidence suggests that glutamine (like vitamin C) might help prevent such infections. Glutamine (often combined with other nutrients) might be useful as a nutritional supplement for people undergoing recovery from critical illness. One preliminary, double-blind trial suggests that glutamine might support standard therapy for angina. NOTE: Angina is too dangerous a disease for self-treatment. If you have angina, do not take glutamine (or any other supplement) except on the advice of a physician. It has also been suggested as a treatment for food allergies, based on a theory called leaky gut syndrome. This theory holds that in some people whole proteins leak through the wall of the digestive tract and enter the blood, causing allergic reactions. Preliminary evidence suggests that glutamine supplements might reduce leakage through the intestinal walls. On the same principle, glutamine supplements have been suggested for people with other digestive problems, such as irritable bowel syndrome, Crohns disease, ulcerative colitis, and the digestive distress caused by cancer chemotherapy. However, there is no real evidence that it works for these conditions.Preliminary evidence suggests glutamine combined with antioxidants or other nutrients may help people with HIV to gain weight. Glutamine has been tried as an ergogenic aid for bodybuilders, but two small trials failed to find any evidence of benefit. Based on glutamines role in muscle, it has been suggested that glutamine might be useful for athletes experiencing overtraining syndrome. As the name suggests, this syndrome is the cumulative effect of a training regimen that allows too little rest and recovery between workouts. Symptoms include depression, fatigue, reduced performance, and physiological signs of stress. Glutamine supplements have additionally been proposed as treatment for attention deficit disorder, ulcers, and as a brain booster. However, there is little to no scientific evidence for any of these uses.

Infections in Athletes Endurance exercise suppresses the immune system. This effect may be due in part to reduction of glutamine in the body, although not all studies agree. A double-blind placebo-controlled study evaluated the benefits of supplemental glutamine (5 g) taken at the end of exercise in 151 endurance athletes. The result showed a significant decrease in infections among treated athletes. Only 19% of the athletes taking glutamine got sick, as compared to 51% of those on placebo. Recovery from Critical Illness One small double-blind study found that glutamine supplements might have significant nutritional benefits for seriously ill people. In this study, 84 critically ill hospital patients were divided into two groups. All the patients were being fed through a feeding tube. One group received a normal feeding-tube diet, whereas the other group received this diet plus supplemental glutamine. After 6 months, 14 of the 42 patients receiving glutamine had died, compared with 24 of the control group. The glutamine group also left both the intensive care ward and the hospital significantly sooner than the patients who did not receive glutamine. HIV-Related Weight Loss Although research is still preliminary, one double-blind placebo-controlled study found that a combination of glutamine and antioxidants (vitamins C and E, beta-carotene, selenium, and N-acetyl cysteine) led to significant weight gain in people with HIV who had lost weight. Another small double-blind trial found that combination treatment with glutamine, arginine, and beta-hydroxy beta-methylbutyrate (HMB) could increase muscle mass and possibly improve immune status. Cancer Chemotherapy A double-blind placebo-controlled trial of 70 individuals undergoing chemotherapy with the drug 5-FU for colorectal cancer found that glutamine at a dose of 18 g daily improved intestinal function and structure, and reduced the need for anti-diarrhea drugs. However, a double-blind trial of 65 women undergoing various forms of chemotherapy for advanced breast cancer that did seek to discover whether glutamine at a dose of 30 g per day could reduce chemotherapy-induced diarrhea found no benefit. Angina Researchers conducted investigations in rats, and found that glutamine could protect the heart from damage caused by loss of oxygen. Based on these findings, they went on to evaluate the effects of glutamine in ten people with chronic angina who were also taking standard medication. In this double-blind, placebo-controlled trial, each participant received a single oral dose of glutamine (80 mg per kg of body weight) or placebo 40 minutes before a treadmill test. A week later, each participant received the opposite treatment. The results showed that use of glutamine significantly enhanced the ability of participants to exercise without showing signs of heart stress. Based on the results in rats, researchers suggest that a higher dose of glutamine would be worth trying. Crohns Disease Because glutamine is the major fuel source for cells of the small intestine, glutamine has been proposed as a treatment for Crohns disease, a disease of the small intestine. However, two double-blind trials enrolling a total of 30 people found no benefit. Sports Performance A double-blind, placebo-controlled trial of 31 individuals ranging from 18 to 24 years of age evaluated the potential benefits of glutamine for improving response to resistance training (weight lifting). Participants received either placebo or glutamine at a dose of 0.9 g per kg of lean tissue mass. After six weeks of resistance training, participants taking glutamine showed no relative improvement in performance, composition or muscle protein degradation. Similarly, negative results were seen in a small, double-blind, placebo-controlled trial of weightlifters using a dose of 0.3 g per kg of total body weight.

As a naturally occurring amino acid, glutamine is thought to be a safe supplement when taken at recommended dosages. However, those who are hypersensitive to monosodium glutamate (MSG) should use glutamine with caution, as the body metabolizes glutamine into glutamate. Also, because many anti-epilepsy drugs work by blocking glutamate stimulationin the brain, high dosages of glutamine may overwhelm these drugs and pose a risk to people with epilepsy. Finally, in one case report high doses of the supplement L-glutamine (more than 2 g per day) may have triggered episodes of mania in two people not previously known to have bipolar disorder. Maximum safe dosages for young children, pregnant or nursing women, or those with severe liver or kidney disease have not been determined.

If you are taking antiseizure medications, includingcarbamazepine, phenobarbital, Dilantin (phenytoin), Mysoline (primidone), andvalproic acid (Depakene), use glutamine only under medical supervision.