Glutamine is an important, non-essential amino acid that is found in high concentrations in your blood plasma. "Non-essential," in this context, means that you need it, but you don't need to eat it because your body can synthesize it. You can synthesize glutamine in your muscle tissue. It can affect amino acid metabolism and nitrogen balance in your muscles. Glutamine is important in a number of metabolic processes related to muscle recovery and exercise, so it has been used as a nutritional supplement for bodybuilders and athletes looking to gain muscle size and strength. Glutamine supplementation has not been evaluated by the Food and Drug Administration; therefore, you should consult your physician prior to use.
Glutamine and Hormones
Glutamine is involved in the production and regulation of human-growth hormone, or HGH. In his book "Nutrition for Health, Fitness, and Sport," nutritionist Melvin H. Williams writes that glutamine has been shown to increase HGH levels and stimulate protein synthesis, or the formation of new proteins, by increasing muscle-cell volume. Glutamine acts as a precursor to growth-hormone-releasing hormone, or GHRH, which is produced by your hypothalamus gland and stimulates your anterior pituitary gland in your brain to release growth hormone. This hormone, in turn, increases the rate of muscle growth.
Glutamine is considered gluconeogenic and has the ability to create muscle glycogen from blood glucose, which influences energy production during exercise. Increasing the availability of glucose to your skeletal muscles during exercise may increase exercise performance, intensity, and recovery, particularly during repeated bouts of intense resistance training, such as the methods used by many bodybuilders. Glutamine also aids in the removal of amino acids, pyruvate, and other byproducts of energy metabolism in your muscles, thereby enhancing your recovery in between sets of resistance training exercises.
Over-training syndrome is a condition that results from exercising more intensely and frequently than your body is capable of handling and is associated with symptoms of excessive training, such as fatigue, insomnia, decreased muscle strength, and increased heart rate. Bodybuilders, due to their intense weightlifting programs, may be more susceptible to over-training than other athletes. Glutamine supplementation may reduce the effects of over-training syndrome by increasing the rate of muscle recovery following exercise due to an increase in the rate of protein synthesis in your muscles.
Supplemental glutamine is considered to have a low toxicity, and is generally well tolerated. The 2001 "Sport Supplement Encyclopedia" states that glutamine supplementation may result in gastrointestinal distress, including nausea, diarrhea, and upset stomach. Less common effects of glutamine supplementation include an increase in depression, anxiety, and nervousness, based on glutamine's stimulatory effect on certain brain chemicals and hormones, although more research needs to be conducted in this area. Bodybuilders taking other growth-hormone stimulators may observe an increase in the severity of the possible side effects of glutamine.
- "Sport Supplement Encyclopedia"; Jeff Stout and Jose Antonio; 2001
- "Nutrition for Health, Fitness, and Sport"; Melvin H. Williams; 2002
- "Physiology of Sport and Exercise"; Elaine N. Marieb; 2004
- "The Journal of Nutrition": Dosing and Efficacy of Glutamine Supplementation in Human Exercise and Sport Training
- University of Maryland Medical Center: Glutamine