Glutamine is the most common amino acid (nutrient building block) in the body. The body can produce enough glutamine to meet its daily requirements. However, during times of extreme stress (such as after heavy exercise or an injury), your body may require more glutamine than it can produce. The majority of glutamine is stored in the muscles, followed by the lungs, which produce the majority of glutamine. Athletes who train for endurance events (such as marathon running) may have less glutamine in their cells. It is usual for them to get a cold after having participated in an athletic event. Some experts believe this is due to the role glutamine plays in the immune system. One study found that taking glutamine supplements resulted in fewer infections in this specific group of athletes. However, this is not true for exercisers who work out at a moderate intensity. Glutamine is available as a standalone supplement or as part of a protein supplement. These are available as powders, capsules, tablets, or liquids. Glutamine protects the mucosa, which is the lining of the gastrointestinal tract. As a result, some researchers believe that people with IBD (ulcerative colitis and Crohn’s disease) may be deficient in glutamine. However, two clinical trials found that taking glutamine supplements did not improve Crohn’s disease symptoms. More investigation is required. In the meantime, consult your doctor before using glutamine for IBD.