By: Taro Moberly, pursuing BS, Biology, Cal Poly San Luis Obispo, 2012
Fluid Sports Science Research Team
Glutamine supplementation has long been used in medicine to treat those suffering from burns, trauma, and even cancer. In addition, glutamine has been used to increase the rate of wound healing and to quicken the recovery of those who undergo surgical operations. The supplement has been growing in popularity in the bodybuilding world for its ergogenic effects, which may prove beneficial for endurance athletes as well.
What is it?
Glutamine is the most abundant of 22 standard amino acids in the human body, accounting for up to 60% of the body’s free amino acid supply. Glutamine is synthesized primarily in skeletal muscle, but production also takes place in adipose fat tissue, the lungs, the liver, and the brain.
Glutamine has several roles within the body during normal function. Aside from being a building block for protein synthesis and important in skeletal muscle protein regulation, glutamine acts as a nitrogen donor, transporting nitrogen and nitrogenous wastes between organs. In addition, glutamine serves as a source of fuel for several key parts of both the immune system and the gastrointestinal tract. The brain also utilizes glutamine to create substances associated with neurotransmitters.
The American Dietetic Association lists glutamine as a conditionally essential amino acid. This means the body regularly synthesizes an adequate amount of glutamine for normal function. During times of increased metabolic stress such as during injury, illness, or exercise, the body’s glutamine requirement exceeds production, and provision becomes necessary.
What will glutamine supplementation do to increase my performance?
Because exercise is a form of increased metabolic stress, it causes the depletion of glutamine in the body. The rate of depletion depends on the intensity and length of exercise. Glutamine levels that become too low can have damaging effects on the body. Supplementation can ward off these effects in several ways.
1. Glutamine is an anticatabolic agent, meaning it prevents the breakdown of muscle tissue to be metabolized. Boosts in glutamine levels increases the hydration of muscle cells, a promoter of anabolic processes. When glutamine levels drop during intensive exercise, catabolism takes place and muscle tissues become damaged. This may also be useful in athletes undergoing a calorie deficient diet in order to drop to competition weight, as calorie deficiency triggers catabolic metabolism in the body.
2. Because glutamine fuels the immune system, depletion of glutamine stores can have detrimental effects on the athlete’s health. Supplementation of glutamine keeps the immune system fueled during intensive exercise, preventing ill effects associated with overtraining. In a study in which athletes consumed a glutamine supplement after a marathon race, only 19% experienced illness during the following week, compared to 51% of athletes who did not take such a supplement.
3. Glutamine is an essential for the synthesis of glutathione (GSH), the body’s natural antioxidant. Studies have linked glutamine deprivation to increases in cell sensitivity to neuroblastoma, or cancerous tumors. This is likely due to the body’s inability to produce enough GSH to protect cells from oxidative damage. Glutamine should therefore be replenished sufficiently especially in those who partake in intensive exercise.
4. Glutamine has an anti-inflammatory effect that reduces inflammation in muscle tissues post exercise or injury. This helps reduce swelling and delayed onset muscle soreness after a workout and assists in proper recovery. Because of this benefit, glutamine supplementation is used by medical professionals to help patients recover from surgery, and to treat patients of trauma, burns, and other ailments.
5. Glucose and glycogen synthesis has been linked to glutamine levels in the body. Glutamine acts as a substrate for gluconeogenesis and glycogenesis. Studies have shown a sevenfold increase in glucogenesis after glutamine supplementation, and a twofold increase in muscle glycogen after post-exercise glutamine consumption. It is not known, however, if glutamine is as effective of a substrate as carbohydrate for glucose and glycogen synthesis.
6. There is some evidence that glutamine may reduce glucose and insulin resistance due to a high fat diet, as well as reduce weight gain due to high fat consumption. A study in mice predisposed to obesity and hyperglycemia found that glutamine supplementation reduced body weight as well as hyperglycemia and hyperinsulinemia.
Is glutamine supplementation safe?
Glutamine supplementation has not been found to have any negative or harmful effects in humans, even when used in the long term. Dosages as high as 0.3g per kg body weight (21g glutamine for a 70kg athlete) per day have not shown any evidence of toxicity. That said, those with liver or kidney problems should avoid glutamine supplementation.
Supplementing your diet with even smaller dosages of 2.5 to 5g of glutamine daily can have positive results on your training and performance. By replenishing the glutamine utilized by your body during exercise, you increase your body’s ability to perform during and recover after your workout while maintaining bodily health. As there are no known adverse side effects, glutamine supplementation can be recommended to athletes looking to get the most of their body during exercise.
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