Glutamine Supplementation

Question:

I work for a national health club chain, and one of our trainers is pushing our glutamine, stating that it removes the cortisol away from the muscle. My co-workers and I want to know if there is any validity to his statements since he is telling hundreds of members this information.

Answer:

Before we even get into the validity of this claim and whether glutamine supplementation is useful or not, the big concern here is whether this trainer has any credentials whatsoever to make such claims. Too often, trainers make claims regarding supplements simply on speculation and a few magazine articles and ads and not based on scientific studies. This trainer should be approached and asked to produce scientific research papers that prove his/her belief regarding glutamine supplementation with respect to cortisol. In a world of lawsuits, trainers need to be particularly cautious about what they recommend to clients and gym members. And if trainers like this one stand to benefit financially from recommending supplements, then you have the added concern regarding a conflict of interest. Think about it: what are the chances that every person this trainer is telling to take glutamine really needs it? Slim to none. Does everyone have a problem with cortisol? NO!!! I would really like to know how s/he knows that the supplement is going to miraculously have this effect on cortisol. And how would this trainer know what amount is needed and for how long?

What is Glutamine?

Glutamine is an amino acid that is an important energy source of immune cells and is the most abundant amino acid in human blood and muscle. It also plays a major role in protein metabolism.

Glutamine supplementation has become increasingly popular as the proposed benefits of supplementation include the following:

1. Since blood glutamine levels fall during and after prolonged exercise and other stressful states such as trauma or surgery, it is possible that supplementation with glutamine can prevent illness (e.g., getting sick after a marathon race) since glutamine is a fuel source for immune cells.
2. Because glutamine is present in high amounts in the muscle and decreases during exercise, some speculate that supplementation can increase hypertrophy.
3. The addition of glutamine to a post-workout meal can help increase glycogen (carbohydrate) stores.

The controversy is whether glutamine supplementation works or not. There are those that strongly believe in this supplement as a training aid. For the most part, supporters like to highlight the studies that show some benefit while for one reason or another they ignore the many studies that show no performance or health benefit that comes with glutamine supplementation. It is my belief that when it comes to supplements like glutamine, too many people in the fitness industry (like trainers) stick their heads in the sand and fail to examine the issue to its full extent. Just because something is reduced by exercise does not necessarily mean that taking more than you get in your diet is going to automatically bring about great improvements. The human body and its metabolism is much too complex for such simplicity. Indeed, glutamine may benefit some (e.g., those who over-train), but those who are recommending it need to be much better informed.

As for the question at hand, I performed an exhaustive search of research (likely this trainer did not) using PubMed (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) to find a connection between glutamine, cortisol and skeletal muscle. I could not find any peer-reviewed research papers on this subject. This trainer really should be forced to provide solid evidence for why s/he is recommending glutamine for this purpose.