In recent years, since it first appeared among the bodybuilders' phials and jars, glutamine has been repeatedly subject to diatribes on its true effectiveness.
We find this amino acid in a abundant quantity produced in our body. In fact, it can be defined as "semi/partially" essential, since the body can produce it autonomously to support the body during certain health situations, such as serious diseases and burns, or extreme stress, such as those caused by intense training phases, which can lead to severe damage of the muscle fibres.
As I said, in these cases the body can produce it autonomously, but now that its functions are well known, glutamine is taken as a supplement. Over the years, it has even become the first choice for many, thanks to its (according to them) significant efficacy at a muscular level.
Is it all true? Should we all rush out to buy glutamine?
As a skeptical man "of science", who has often emphasised the literature against its ever-so majestic effect, I am always ready to question everything and everyone, first and foremost my ideas and beliefs. I'm here to at least try to make things clear.
Let's delve into my "brain files" from my time at university, trying my best not to be boring, to explore what glutamine does and why we should use it as a supplement if the body can produce it by itself.
The first reason why it is "special" is precisely because it is produced by the body in case of need from other amino acids (arginine, ornithine and proline) in skeletal muscle, where it is present in great abundance (60%), but it is also stored in the gut, white blood cells and the kidneys.
Among its many uses, we primarily see those that would catch the eye of a bodybuilder or any other athlete.
The chemical formula of glutamine (to the left) and its molecular representation (to the right)
Glutamine is implicated in the regulation and synthesis of proteins, as a support to muscular cannibalism during phases in which the body has been subjected to stressful situations, such as an intense workout, where it is used by the muscles faster because glutamine acts as a nitrogen and carbon donor and this is an important element for the formation and maintenance of the musculature.
“Is that all?” Isn't it enough, given glutamine's fundamental function? But its overt activities go far beyond this.
It promotes the entry of water, amino acids and other substances into the cells (remember that a hydrated cell is a cell anabolism).
This is one of the leading reasons why glutamine is taken for sports use, because of its power hydrating cells which also considerably influences the increase of glycogen stores.
Not only that, its usefulness as a supporting element is crucial in influencing signals to the much-discussed mTor, a kinase protein (basically an enzyme) that possesses the "unique" function of regulating growth, proliferation, motility, the survival of cells and protein synthesis.
Glutamine also adds an active value to the use of BCAA cousins, in particular the important Leucine. Not to forget its being so loved by connoisseurs of low carb/keto, high fat diets or bodybuilder agonists in pre-contest moments which often sees carbohydrate intake decrease to minimal levels and therefore threaten to bring the safeguard of the muscles into play, for its capability to quickly convert into glucose and to have fuel with a buffering effect on the muscle protein.
Energetically supporting lymphocytes and macrophages, which is no small feat for athletes who, especially in periods of overtraining or fewer calories, can see their immune system becoming less efficient against viral and bacterial infections
Glutamine is a veritable transporter of non-toxic amino groups, that can cross the cell membranes.
This enters the bloodstream and reaches the liver where the liver mitochondria releases its amino group which is converted into NH4+ or ammonium ion.
Ammonium ion is toxic to cells in the body and, in particular, the brain. In the liver, NH4+ is incorporated into the non-toxic urea molecule. The urea produced by the liver is transported through the blood to the kidneys for urinary excretion.
Acting indirectly as "buffers", that is as a substance to buffer the acidity. Glutamine is used by the kidney to synthesise ammonia. Ammonia molecules spontaneously accept protons which are excreted, such as ammonium ions, and the excretion of ammonium thus eliminates the protons, mitigating acidosis. When the blood pH is low glutamine is derived from the muscles to restore homeostasis. This is the reason why acidosis causes the release of muscle glutamine. Once it reaches the kidneys, glutamine is converted to bicarbonate. The "acid-base" balance argument, which is very popular nowadays (it could be cause for another future article), involves the idea that by taking a glutamine supplement it is possible to balance the pH while sparing muscle glutamine.
It carries out stimulating activity in the brain.
Glutamine is able to penetrate the blood-brain barrier and to then enter the brain where it is converted into glutamate, the most important and prevalent excitatory neurotransmitter in the central nervous system. (Excessive levels of glutamic acid formed by the metabolism of the nervous system can be toxic to neurons).
Here, I must say that recent scientific literature has largely questioned the fact that the acute stimulation of endogenous GH is beneficial for the increase in muscle gains. According to these recent findings, the increase in systemic hormones such as growth hormone and testosterone induced, for example, by exercise, has no correlation with increased hypertrophy, strength and protein synthesis.
Other papers have reported that stimulators of GH amino acids, if taken around the same time as exercise with weights, have never demonstrated an increase in muscle mass compared to no intake.
These facts, combined with the non-significant results obtained by the long-term supplementation of glutamine in conjunction with the exercise with weights, would be further confirmation of the lack of efficacy of glutamine in these circumstances. Therefore this "myth" is dispelled. But it is only one goal against versus those in favour.
As we have seen, the list of processes in which it is involved is long, it can be an interesting bonus for "muscle health" and other factors for athletes, given the easy depletion of its stocks. Kidneys, for example, use large quantities to compensate for the acid-base balance and, in the case of bodybuilders or in any case of individuals who ingest large amounts of protein, acidosis increases more easily, so as then increase the glutamine request used as a buffer, another interesting compensation mechanism of the body.
But considering its effectiveness "in the field" of bodybuilders or athletes more directly, with regards to muscles or performance, does it or does it not serve to increase them? When I am asked this question, I always specify that glutamine can be "eliminated" in the first step before reaching the bloodstream (the gastrointestinal tract is particularly greedy), so users really get very little if we consider that can be deducted up to 90%!
So, summing up a long diatribe that often sees inconsistencies in the scientific literature itself (on the potential effectiveness as a supplement and on performance enhancement) I would say that in the case of diseases, conditions of fasting, low calorie intake, supporting muscle growth and during periods of particularly intensive training, the body will ask for a lot, so supplementation is advisable to support an "internal" demand which is more important for health in general and not only that of the muscles.
An "effective" dose to reach the systemic circulation in helpful quantities can be up to 20-30 g.
For "critical" situations during particular forms of organic stress detailed above, it is divided into doses of 5-10 g.
This will result in quick assistance for the gastrointestinal system, where a "repairing" action is carried out on the intestinal mucosa, creating true regenerative lymph blood for the intestinal cells. The deterioration of the intestinal wall leads to easy interference with viruses and bacteria, as well as having a less efficient absorption system resulting in very few nutrients that can reach the muscles, susceptibility to infections, easy allergies and annoying fermentation. It is a bad obstacle for those seeking maximum performance from their training!
If we do not have strong gut health, we cannot properly absorb what we eat, we create an irritated atmosphere with all of the associated hassles and easy permeation or victory of many bacteria and viruses with which we come into contact.
From my point of view it is right here that you should notice the real reason for taking glutamine regularly, not so much for what it can do directly to our muscles (although I still support the hydration of the cell and its shielding effect at certain critical periods) but for that very important organ: the gut (called the second brain!) where you decide what nutrients to ingest and absorb, affecting the whole immune health in a fundamental way.
If you wanted to essentially aim "only" at this objective (which I think of essential importance) two intakes of 5g/day are sufficient, recommended preferably on an empty stomach, or even an hour before meals to maximise absorption.