Glutamine

Supplement Forms/Alternate Names

• L-Glutamine

Uses

• Sources
• Therapeutic Dosages
• Therapeutic Uses
• What Is the Scientific Evidence for Glutamine?
• Safety Issues
• Interactions You Should Know About
• References

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 body's 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.

Sources

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. Typical daily intake from food ranges from approximately 1 to 6 g.

Therapeutic Dosages

Typical therapeutic dosages of glutamine used in studies ranges from 3 to 30 g daily, divided into several separate doses.

Therapeutic Uses

Endurance athletes frequently catch cold after completing a marathon or similar forms of exercise. Preliminary evidence, including one small double-blind, placebo-controlled trial, suggests that glutamine supplements might help prevent such infections. 1-5

Another small double-blind, placebo-controlled trial suggests that glutamine might support standard therapy for angina. 34Note : 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.

Because, as noted above, cells of the intestine use glutamine for fuel, the supplement has been tried as a supportive treatment for various digestive conditions, with mixed results. Tested uses include reducing diarrhea caused by the drug nelfinavir (used for treatment of HIV ), 37 digestive distress caused by cancer chemotherapy , 15,16 and symptoms of inflammatory bowel disease. 9-14

Glutamine appears to help reduce leakage through the intestinal wall. 7,8,38 On this basis, glutamine has also been suggested as a treatment for food allergies , according to the idea that in some people whole proteins leak through the wall of the digestive tract and enter the blood, causing allergic reactions (so-called leaky gut syndrome). However, as yet there is no reliable evidence that glutamine actually provides any benefits for food allergies.

Preliminary evidence suggests glutamine combined with antioxidants or other nutrients may help people with HIV to gain weight. 17,18 Glutamine (often combined with other nutrients) also appears to be useful as a nutritional supplement for people undergoing recovery from major surgery or critical illness. 6,39

Glutamine has been tried as an ergogenic aid for bodybuilders, but two small trials failed to find any evidence of benefit. 35,36

Based on glutamine's 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.

What Is the Scientific Evidence for Glutamine?

Safety Issues

As a naturally occurring amino acid, glutamine is thought to be a safe supplement when taken at recommended dosages. There is strong evidence that glutamine is safe at levels up to 14 g per day, although higher dosages have been tested without apparent adverse effects. 42

Nevertheless, 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 stimulation in the brain, high dosages of glutamine might conceivably overwhelm these drugs and pose a risk to people with epilepsy. 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. 33 In a small randomized trial including 30 older people, L-glutamine did not cause any clinically significant changes in lab tests. The researchers did urge caution, though, since there were some statistically significant changes for certain kidney levels. 44

Maximum safe dosages for young children, pregnant or nursing women, or those with severe liver or kidney disease have not been determined.

Interactions You Should Know About

If you are taking:

• Antiseizure medications, including carbamazepine , phenobarbital , phenytoin (Dilantin) , primidone (Mysoline) , and valproic acid (Depakene) : Use glutamine only under medical supervision.
• Nelfinavir or other protease inhibitors for HIV, or cancer chemotherapy drugs: Use of glutamine may reduce intestinal side effects.

References

• EBSCO CAM Review Board
• 201207
• 20120725