Glutamine is the most abundant amino acid in our body (70% in myocytes), and it crosses cell membranes very easily. It is well known that glutamine levels tend to decrease under all conditions of stress. It has so many potential functions that it is difficult to determine which are the most important, and even more difficult to create a “classification” of those with the greatest impact.

It is a precursor of purine and pyrimidine bases, which are involved in RNA and DNA synthesis. It is a precursor of all amino acid synthesis, and all non-essential amino acids can be synthesized from it. It therefore has a potentially anticatabolic effect, and ensuring its presence and availability promotes protein synthesis triggered by exercise. Its role in cell synthesis is particularly interesting, especially in cells with a very high turnover, such as those in the intestinal mucosa and lymphocytes. This amino acid can play an important role in intestinal function, which is often affected during periods of stress. Supporting intestinal and lymphocyte function reduces susceptibility to infections, which often affect athletes during the loading phase.
In addition to these specific functions, glutamine also transports nitrogen between organs, supporting general bodily and metabolic functions that necessarily accelerate during both physical exercise and pathological stress.

Its important role in gluconeogenesis should be considered: while it is true that a well-balanced diet should minimize the activation of gluconeogenesis, very long exercise sessions are becoming more popular, and in these cases it is very difficult to do without the energy provided by amino acids. In this respect, glutamine plays an important role.

Also remember its vital role in collagen synthesis (through proline and hydroxyproline), which protects tissues that are particularly stressed and helps repair those that are injured.

This amino acid generally has a beneficial role under stressful conditions such as inflammation; studies show that when taken, it reduces the amount of circulating inflammatory cytokines (4).

In short, glutamine’s multifaceted nature does not emphasize any one specific function, giving it a distinctive character. Its preventive and protective benefits for athletes should not be overlooked.

There is no reason for people who exercise recreationally to use it. Although no harm caused by glutamine is known, even when used for long periods, it is advisable to stick to a daily dose of 0.1 to 0.3 g/kg.