Some say it doesn't work, I say it's cheap and wouldn't hurt to take it. 1. What is it and where does it come from? The extremely popular amino acid L-Glutamine can be found in protein powders, beans, meats, fish, poultry, dairy products, and of course, L-Glutamine supplements from Bodybuilding.com. 2. What does it do and what scientific studies give evidence to support this? Glutamine is highly in demand throughout the body. It is used in the gut and immune system extensively to maintain optimal performance. 60% of free-form amino acids floating in skeletal muscles is L-glutamine. L-glutamine plays a very important role in protein metabolism, and it appears to be a very important nutrient for body builders. When supplemented, it may help body builders reduce the amount of muscle deterioration that occurs because other tissues that need glutamine will not rob the glutamine stored in the muscle cells. Research shows that after intensely working out, glutamine levels in the body are reduced by as much as 50%. Since the body relies on glutamine as cellular fuel for the immune system, scientific studies have shown that glutamine supplementation can minimize the breakdown of muscle tissue and improve protein metabolism. Its effects on replenishing the body after stress or trauma have been shown in Europe where it is commonly given to patients in hospitals. Glutamine's cell-volumizing effects have also been shown in several studies. No conclusive studies have been done to evaluate the effects of L-glutamine supplementation on weight-training adults; however, a recent study showed up to a 400% increase in growth-hormone levels when as little as 2 grams of free-form L-glutamine supplement was consumed! 3. Who needs it and what are some symptoms of deficiency? Bodybuilders can particularly gain from the intake of glutamine. Since bodybuilders use a lot of their glutamine when working out, they are more susceptible to health related problems, as the immune system relies heavily on this amino acid. Catabolism or muscle break down can occur if the body robs muscles of glutamine for use elsewhere such as nitrogen transport or maintaining the immune system. Glutamine supplementation is certainly important in keeping muscles building--not deteriorating. 4. How much should be taken? Are there any side effects? Bodybuilders can benefit by taking ten grams of L-glutamine per day, although clinical studies have not determined a precise amount for muscle metabolism optimization. There are no side effects associated with L-glutamine, because it is a nutrient naturally occurring in the body. Reports of an upset stomach are associated with ingesting a great deal of glutamine, using smaller doses is recommended if this occurs. Research has shown a significant correlation between survival in severely infected patients and the muscle glutamine concentration. Supplying glutamine helps the metabolic processes associated with recovery. So as an athlete glutamine can help you in the following areas: Stimulates muscle protein synthesis by donating nitrogen to build proteins. Increases growth hormone which can induce positive body composition and mood changes (Note: A study done in 1995 by LSU College of Medicine showed that a surprisingly small oral dose of 2 grams of glutamine raised GH levels more than 4X over that of a placebo. Age did not diminish the response of the volunteers who ranged in age from 32 to 64 years.) Decreases muscle catabolism during exercise Increases endurance by replenishing glycogen under conditions of glycogen depletion Decreases muscle recovery time Decreases the chances of illness/infection by boosting your immune system Prevents over-training from high loads and long duration activities (recall that blood glutamine levels are an excellent marker of anabolic status).