Everything you wanted to know about: L-Glutamine

L-Glutamine is the most abundant non-essential amino acid in the body. It is stored in the blood and muscles, and is released during times of stress or illness. L-Glutamine is found in foods such as meat, poultry, fish, eggs, soy, legumes, whole grains, and dairy products. Approximately 5-10 grams per day of L-glutamine is consumed in the diet.

During times of stress, L-glutamine becomes conditionally essential, meaning that it is needed by the body in either food or supplement form. One instance is during catabolic stress, where L-glutamine levels can drop more than 50% (1).

L-Glutamine helps to regulate protein synthesis, improves immune function, aids in DNA synthesis, promotes muscle growth, and decreases muscle catabolism by protecting muscles from the harmful effects of cortisol. Two-gram doses at a time have been found to stimulate the release of growth hormone, which may, in part, be responsible for its anabolic effects (5). Other research has focused on L-glutamine’s role in cancer therapy, as well as to help treat ulcerative colitis, IBS, and Crohn’s Disease.

Plasma L-Glutamine levels tend to be decreased in athletes who train too often and at too high of an intensity for the muscles to fully recover after working out. This leads to a higher incidence of infectious diseases and allergies, slower wound healing, and reduced immune function (3). Low-intensity exercise does not seem to have the same deleterious effects (4).

Athletes may reduce the risk of infections and other negative effects by supplementing with L-glutamine. In an eight-week study, athletes supplemented with L-glutamine and creatine, and significantly increased lean body mass and initial rate of power production during multiple cycle ergometer bouts (2).

The most common dose of L-glutamine is 500-1000mg, 3 times daily. The dosage that you need to take will depend on several factors, such as the intensity and duration of your exercise. Talk to your doctor or nutritionist to determine the best dosage for you.

References

1. Askanazi J, Carpentier YA, Michelsen CB, et al. Muscle and plasma amino acids following injury: Influence of intercurrent infection. Ann Surg. 1980;192:78-85.
2. Lehmkuhl M, Malone M, Justice B, et al. The effects of 8 weeks of creatine monohydrate and glutamine supplementation on body composition and performance measures. J Strength Cond Res. Aug2003;17(3):425-38.
3. Nieman DC. Exercise and resistance to infection. Can J Physiol Pharmacol. May1998;76(5):573-80.
4. Robson PJ, et al. Effects of exercise intensity, duration and recovery on in vitro neutrophil function in male athletes. Int J Sports Med. Feb1999;20(2):128-35.
5. Welbourne TC, et al. Increased Plasma Bicarbonate and Growth Hormone After an Oral Glutamine Load. American Journal of Clinical Nutrition. 1995;61:1058-61.