Where it comes from: Glutamine is the most abundant amino acid in the body—despite the fact that it's not essential. Most glutamine is stored in muscles followed by the lungs, where much of the glutamine is made. It's involved in many metabolic processes, and is the principal carrier of nitrogen in the body and is an important energy source for many cells.
What it'll do for you: "Glutamine has become increasingly popular among athletes, as it is believed that it helps prevent infections following athletic events and speeds post-exercise recovery," explains registered dietitian and American Dietetic Association spokesperson Jim White. Doctors use glutamine when men are in a catabolic state of injury or after surgeries. In the commercial world, glutamine is also marketed as a supplement used for muscle growth in bodybuilding and demanding sports. Here, a more detailed look at what it can do:
- Ease trauma and burns
A double-blind study published in 2003 looked at 45 adults with severe burns—some were given glutamine supplements and others were given a control mixture. The researchers reported that glutamine supplementation in adult burn patients reduced blood infections by a factor of three, prevented a certain pathogen and reduced mortality rates.
- Speed wound healing in postoperative patients
In a 2001, a study looked at patients who underwent elective surgery. Those who were given glutamine supplements intravenously showed improvement in nitrogen balance throughout their body, a corrected decreased glutamine concentration in the skeletal muscle amino acid pool and enhanced protein synthesis. Other randomized blind trials reported a decreased length in hospital stay in postoperative patients receiving glutamine supplementation.
- Halt the breakdown of muscles and stimulate new growth
Amino acids form the proteins that help build much of the body's tissue—including muscle. During intense exercise blood and muscle levels of glutamine tend to fall. Additionally, studies have proven that, after a hard workout, muscles are torn down. To reverse this effect, nutrients must be fed to the muscles and protein synthesis must be stimulated to build new muscle. "If we supplement our body with glutamine before an intense training we allow our body to keep a high supply of glutamine in the muscles and stop them from breaking down," White explains. "This means the body can use the glutamine in the muscles to synthesize protein and build muscle mass."
- Helps relieve treatment-related side effects of cancer
Doctors often prescribe glutamine supplements to cancer patients to help treat diarrhea, inflammation of the mouth lining, sore throats and tingling fingers and toes. Positive results have been found with patients receiving radiation therapy, bone marrow transplants and certain chemotherapies.
Suggested intake: "The body can make enough glutamine for its regular needs," says White. Because the body synthesizes it, glutamine deficiency is not very common. Glutamine is also found in plant and animal proteins such as beef, pork and poultry, milk, yogurt, ricotta and cottage cheese, tofu, beans, eggs, raw spinach, raw parsley and cabbage.
For those looking to take glutamine for muscle mass, note that adults should avoid ingesting more than 40 grams per day.
Supplements are available in powder or capsule form. The powder form is often preferred by customers because the dosage is bigger in one small scoop compared to a few capsules. When mixed with liquids, glutamine powder is virtually tasteless.
There are two types of glutamine supplements—glutamine peptides and L-glutamine. L-glutamine is "free form" and not bonded to other amino acids. Most supplement takers prefer glutamine peptides, which are bonded to other amino acids and are more stable and better assimilated by the body. However, most studies showing the benefits of glutamine supplements use L-glutamine and not peptides.
Associated risks/scrutiny: Glutamine supplements are considered possibly safe for most men when taken orally, but the potential side effects of glutamine are unknown.