Glutamine is a conditionally essential amino acid, since although it is synthesized by the human body, in some conditions it requires an adequate intake through the diet.
As the most abundant amino acid in the human body, the need for glutamine can explode during stress, surgical trauma, burns, tumours or particularly intense exercise.
Glutamine is widely present both in products of animal origin, such as meat, fish, eggs and dairy products, and in vegetable products.
From a biological point of view, glutamine intervenes:
- In the metabolism and excretion of nitrogen compounds (urea cycle);
- In the transport of amino groups;
- In the synthesis of nucleotides;
- In the synthesis of bioactive molecules such as glutathione and glucosamine;
- In maintaining the functionality of the immune system.
In view of its biological role, glutamine is successfully used in both clinical and sports fields.
Functions and Biological Role
The glutamine kicks in:
- in ammonia detoxification:
- Glutamine is a real carrier of amino groups, non-toxic, which can cross cell membranes. Glutamine enters the bloodstream and reaches for the liver. Within the hepatic mitochondria, glutamine releases its amino group, which is converted into NH4+ or ammonium ion.
- Ammonium ion is toxic to the cells of the body, in particular to 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.
- In immune activity, where it plays an energetic supporting role in rapidly multiplying cells such as lymphocytes and macrophages.
- While moderate exercise increases resistance to infections of various types, comprehensive exercise, especially when combined with low-calorie diets, increases sensitivity to viral and bacterial infections.
- In brain activity, where it performs a stimulating activity. Glutamine can penetrate the blood-brain barrier and enter the brain, where it is converted into glutamate, the most important and widespread excitatory neurotransmitter of the central nervous system. Glutamine is also a precursor to GABA, a neurotransmitter that has inhibitory effects on nerve transmission.
With regard to the functions of major sporting interest, glutamine also seems to:
- In increasing the volume of muscle cells, promoting the entry of water, amino acids and other substances into the cells. This activity, according to some researchers, would stimulate protein synthesis by promoting the increase in muscle mass.
- In over-training syndrome, there is in fact a relationship between the permanent decrease in plasma glutamine levels and the appearance of over-training symptoms (chronic fatigue, weight loss, loss of appetite, appearance of minor infections, nausea, depression, apathy, increased heart rate at rest and decreased heart rate of training). According to some researchers, the administration of glutamine and branched amino acids would therefore be useful during periods of intense training to reduce the risk of over-training.
- In recovery after an effort: some studies show a role of glutamine in promoting the increase of muscle glycogen stocks during recovery, probably due to the increased entry of water into the cells (remember in this regard that water is essential in glycogen synthesis, as for every gram of glycogen produced about 2.7 g of water bind to it).
- In the growth hormone secretion stimulus; if taken in conditions of low glycaemia levels, glutamine seems to stimulate GH secretion. To optimise this action, glutamine should be taken before going to bed.
- In the detoxifying action and in the regulation of the blood and urinary pH with a buffer effect (it releases ammonia at renal level, which is charged with an H+ hydrogen, transforming into NH4+ ammonium ion, which is then eliminated with urine).
- In the antioxidant action: it intervenes in the formation of glutathione, a powerful exogenous antioxidant consisting of glycine, cysteine and glutamic acid. The latter can be obtained from glutamine by the release of the ammonium ion.
Why do you use glutamine? What’s it for?
The usefulness of glutamine supplementation is closely associated with the scope of application.
In the clinical field, glutamine is used as an agent:
- Immunomodulating agent;
In sports glutamine is attributed to ergogenic, anti-catabolic and protective properties.
All this would be ascribable to the valuable biological role of glutamine.
Properties and Effectiveness
What benefits has glutamine shown in the course of studies?
A correct treatment of the integrative efficacy of glutamine cannot disregard the appropriate discrimination of the fields of application.
Glutamine and clinical
In the clinical setting, the use of glutamine, at significantly higher dosages than sports doses, would have proved useful under various conditions.
More specifically, glutamine:
- It would protect the intestinal mucosa from damage induced by chemo and radiotherapy;
- It would reduce the permeability of the intestinal mucosa and the consequent non-specific activation of the mucosal immune system; this effect could prove valuable in the treatment of dripping bowel syndrome, irritable bowel syndrome and inflammatory bowel disease.
- It would safeguard normal cell turnover;
- It would preserve the proper function of the immune system;
- It would counteract the ongoing structural and functional decline of sarcopenia and cachexia.
Glutamine and sport
Different, and unfortunately not fully accepted by the scientific community, would be the biological potential of glutamine in sport.
This amino acid is in fact ascribed to this amino acid:
- Detoxifying properties, very important during hyper-proteic diets;
- immune-protective activities, valuable during over-training syndrome;
- ergogenic activities;
- Antioxidant activities, valuable in protecting the muscle from the damaging action of free radicals produced during intense training;
- Anabolic activities, linked both to an improvement in the rate of protein synthesis and to the ability denied, to stimulate the secretion of growth hormone.
Despite the abundant use of these supplements in sports, there is still no clear, reproducible and statistically significant data on the biological effectiveness of this amino acid.
Doses and mode of use
How to use glutamine
As proposed by various international public health agencies and well documented in the literature, glutamine dosages would vary significantly depending on the objectives.
In sports, for example, the optimal range seems to be between 1.5 and 4 g daily.
In the clinical setting dosages can increase significantly and reach 8g daily in case of chemotherapy or radiotherapy, or 21g/day in case of severe burns, trauma or other pathologies related to a severe cachectic or immunodepressive state.
To improve absorption and reduce the onset of potential side effects, it is recommended to divide the entire dosage into several daily doses.
In the sports world, depending on the effects you wish to achieve, it is suggested to take them:
- Pre work-out, together with carbohydrates, to optimise performance and reduce oxidative damage induced by intense exercise;
- Post work-out with simple sugars and branched chain amino acids, to optimise the muscle recovery phase;
- Fasting, possibly before going to bed, to stimulate the secretion of GH;
Using glutamine has proven to be safe and well tolerated at the suggested doses.
It has rarely observed transient abdominal disorders such as swelling and constipation.
In psychiatric patients, however, the use of even low doses of glutamine, according to some authors, exacerbated the manic symptoms.
Precautions for use
What do you need to know before you take glutamine?
The use of glutamine supplements should be avoided, or strictly supervised by medical personnel, during pregnancy and lactation.
Similar precautions should be reserved for patients with kidney failure or liver disease.