As already mentioned, glutamine is another amino acid. 

Function

  The intake of glutamine during physical exertion contributes to the increase in muscle glycogen levels, but is not as effective as carbohydrates. It is suspected that this amino acid may act as a precursor for endogenous carbohydrateproduction. Furthermore, although adding it to a solution of carbohydrates and protein does not facilitate the resaturation of muscle glycogen reserves any more than carbohydrates alone do, there is a positive influence on hepatic glycogen stores. They could be a viable alternative to carbohydrate intake in the context of the anabolic window on a low-carbohydrate diet. Again, as previously clarified, glutamine possesses a trophic action on the cells of the immune system, thus helping to reduce infection and inflammation. Relevant among the various studies is the one by Castell (2006), which highlights the effectiveness of glutamine supplementation in preventing infections due to suppression of the immune system (an event that normally occurs following the application of physical load). Unfortunately, not all studies confirm Castell. Finally, according to Bailey (2000), the intake of glutamine could prevent gastrointestinal disorders due to extensive physical loading. In more detail, it has already been mentioned that physical load implies a physiological diversion of blood normally destined for the digestive system into the muscle. The latter, nourished relatively little, becomes more fragile and it often happens that, during exertion, the athlete experiences stomach ache. This is particularly frequent in cases where the load involves continuous shaking of the viscera in the abdominal cavity, of which running is the emblematic example. Well, there is a possibility that taking glutamine may limit the extent of these complaints, but, again, this is not a confirmed thesis.

Negative notes

  Glutamine has no side effects, except those due to excessive amino acid intake (for details see the section on amino acid supplementation for optimising body composition).

Form and posology

  Glutamine supplementation products are commercially available in the form of soluble powder and tablets. Generally, 1-1.5g of glutamine per day is recommended, but in some studies, dosages in excess of 5g have been used. For example, 8g was used in the above-mentioned study showing its efficacy in resaturating liver glycogen stores.