Glutamine, also referred to as l-glutamine, is a conditionally-essential amino acid. This means that while glutamine is not considered an essential amino acid, under conditions of extreme stress such as a traumatic injury to the body, glutamine becomes essential.
Glutamine seems to be particularly important in the digestive, immune, and muscular systems. In fact, it is the most abundant amino acid in human muscle tissue. For this reason supplement companies have focused on offering glutamine pills and powders to supplement users.
The thought is that if glutamine is so prevalent in human muscle tissue that more glutamine will help us to build more muscle. To do this most supplement companies recommend a dose of 5-10 grams of glutamine.
It has also been hypothesized that glutamine will increase growth hormone levels. Although never sufficiently proven, supplement companies recommend a dose of 2-5 grams of glutamine before bed for this purpose.
From my work with athletes I have found a few interesting things with glutamine. The first is that it does seem to have a positive effect on the immune system. If an athlete is going through a stressful time (big competitions or an especially rigorous training cycle) it is very common for the athlete to get sick due to a weakened immune system. By adding in supplemental glutamine I have found that the athlete is much less likely to get sick.
This immune system boost is not as cool-sounding as increasing growth hormones levels, but just think of what getting sick does to your training. You will easily lose at least a few days of productive training, if not more. If supplemental glutamine gives you the ability to train hard for a few extra days then it makes it one of the best muscle building supplements in my book.
In addition to the immune system boosting properties, I have found that glutamine is one of the best muscle building supplements for speeding recovery after intense weight training. The trick is that the dose has to be high enough. I suggest at least 20 grams in your post-workout shake, and as high as 40 grams depending on your individual needs.
The problem is that most combination products only contain a few grams of glutamine along with a few grams of some other substances. What you end up with is a supplement that looks good because it has 100 different compounds in it. But the problem is that none of these compounds are at the correct dosage.
To avoid this I recommend purchasing a stand-alone glutamine powder. That way you are only paying for the important ingredient and you know you are getting the correct dosage.
As always, please remember that glutamine is just a supplement. Adding in 20 grams after your workout wont add pounds of muscle instantly. It must be combined with a properly designed training and nutrition program in order to work to its fullest potential.