Glutamine (L-Glutamine) Supplements

Glutamine Prevents Muscle Breakdown and Improves Immune Function

Glutamine (L-Glutamine) is a naturally occurring non-essential amino acid that is commonly stored in muscles and released into the blood stream during times of stress. It is used by the immune system during times of stress such as physical trauma, burns, starvation, and even during prolonged and intense exercise such as training for marathons. When there is a deficiency of glutamine or when the amount of glutamine is drastically reduced during increased stress, the body experiences a suppression of the immune system until glutamine levels are restored through either diet or supplements.

Intense endurance exercise not only depletes glutamine stores, but has been linked to a temporary decrease in immune system function and a susceptibility to upper respiratory infections and other illness.

Natural Sources of Glutamine

Glutamine is most abundant in high-protein foods, such as meat, fish, legumes, and dairy. Two particularly high vegetable sources are uncooked cabbage and beets. Cooking can destroy glutamine, especially in vegetables. General food sources of glutamine include:

• Animal sources such as meat, fish, eggs, milk, yogurt, and cheese
• Uncooked plant sources including beans, spinach, and cabbage and beets.

Glutamine Supplements for Athletes

Athletes who take glutamine supplements do so in order to prevent muscle breakdown and to improve immune system functioning. Several clinical studies have found that oral glutamine can decrease the incidence of illness and infection in endurance athletes or athletes involved extreme training regimens. Research has also found that glutamine supplements can help maintain muscle mass by preventing protein breakdown and improving glycogen synthesis thereby increasing muscle glycogen stores.

Glutamine is a classified as a nutritional supplement and is not banned by any sport organizations. It can be found in most health food stores in the form of gels or tablets and is often an ingredient in many commercial protein powders. Due to the limited research there are no established guidelines for doses, but About.com’s Guide to Bodybuilding recommends starting at 3 to 5 grams per day.

While the current research of glutamine on immune system function and muscle building is encouraging, it’s still hard to determine the benefit of supplements in otherwise healthy individuals who get adequate nutrients in their diet.

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Vitamins & health supplements. Glutamine

Bowtell JL, Gelly K, Jackman ML, Patel A, Simeoni M, Rennie MJ (1999). Effect of oral glutamine on whole body carbohydrate storage during recovery from exhaustive exercise. Journal of Applied Physiology 86:1770-1777.

Castell LM, Poortmans JR and Newsholme EA (1996). Does glutamine have a role in reducing infections in athletes? European Journal of Applied Physiology 73: 488-490.

Nieman DC and Pedersen BK (editors) (2000). Nutrition and Exercise Immunology. Boca Raton FL: CRC Press.

Rowbottom, DG, Keast D and Morton AR (1996). The emerging role of glutamine as an indicator of exercise stress and overtraining. Sports Medicine. 21.2:80-97.