All about glutamine: role, benefits, deficiency.

What is glutamine? What is its role and what are its benefits? For health as for sports performance, glutamine is a real ally. Nutrimuscle explains everything there is to know on the subject.

Contents :

• What is glutamine?
• The role of glutamine
• Glutamine deficiencies
• Effects in athletes
• Beneficial health effects
• When and how to take glutamine?

What is glutamine?

Amino acid belonging to the family of "conditionally essential" amino acids, glutamine is found in abundance in the body.

The daily diet provides 5 to 10 g, on average. It is found in meat, fish, eggs, seafood, legumes (lentils, chickpeas, beans, etc.), spinach, oilseeds (walnuts, almonds, hazelnuts) and dairy products.

The role of glutamine

It is the most common amino acid in the blood and in the muscles. It plays many roles in our body, including the immune system, protein synthesis, maintaining the integrity of the intestinal wall and acid-base balance. It participates in joint and tendon health by helping to manufacture glucosamine, a component of cartilage.

Glutamine deficiencies

Although our body is quite capable of manufacturing it, certain factors can cause glutamine deficiencies. Among these factors, we find physiological stress (accident, burn, surgery, serious pathology), but also high-intensity physical activity.

Indeed, for bodybuilders or athletes who train regularly, this amino acid is essential: the body's ability to synthesize it is much lower than the destruction caused by exercise. The drop in performance is linked to the decrease in plasma levels of glutamine.

Effects in athletes

Reduce intestinal permeability: Chronic supplementation of this amino acid reduces exercise-induced intestinal permeability, and acute supplementation prevents increased permeability during exercise (4).
Fight against catabolism: This amino acid helps fight against catabolism and accelerates muscle anabolism.
Alleviate body aches: Chronic oral administration of may alleviate muscle tissue damage and inflammation induced by intense physical exertion (5).
Improve performance: According to one study, it appears that acute supplementation of glutamine combined with maltodextrin, 2 hours before exercise, is more effective in preventing the decrease in anaerobic power than the consumption of a pure carbohydrate or glutamine in repeated episodes of the RAST protocol. Thus, supplementation with carbohydrates and the peptide glutamine improved the physical performance of athletes during repeated competitions (6).
Accelerate recovery: After exercise, a reduced availability of glutamine can be considered an overtraining syndrome. Increased availability may contribute to decreased inflammation and health benefits associated with optimal training. Thus, supplementation may improve immunocompetence after intense exercise (7).
A study of glutamine supplementation during a simulated forest fire showed that men and women who ingested glutamine had a slower recovery time than participants who ingested a placebo. Indeed, their fatigue, cellular stress and perceived effort were less significant. Supplementation therefore improves recovery after exercise (8).

Beneficial health effects

In the elderly

Fight against age-related diseases: According to a recent study, the administration of L-glutamine could represent an important therapeutic strategy to reduce muscle loss (sarcopenia) in catabolic and aging diseases (9).

Fight depression: Glutamine is believed to have antidepressant effects through increased blood levels of glutamate and glutamatergic activity in the medial prefrontal cortex (10).

Strengthening of immune defences: It plays a role in the immune system, essential for the proliferation of lymphocytes (11).

In people with intolerances

Food intolerance: Glutamine could improve intestinal mucosal blood flow and reduce intestinal damage especially after a burn, thus reducing the permeability of the intestinal mucosa. (12).

In people with diabetes: supplementation may reduce blood sugar in patients with type 1 diabetes (T1D), who have no residual insulin secretion. (13).

Alcohol-related damage: This amino acid also improves intestinal and liver damage induced by alcohol in particular. (14).

In people with sickle cell disease: A study in patients with sickle cell disease showed that in children and adults with sickle cell anemia, the median number of pain attacks over 48 weeks was lower in patients taking oral l-glutamine. (15).

For people wishing to lose weight

According to one study, the administration of glutamine reduced waist circumference and serum lipopolysaccharide levels in overweight volunteers . In the group of individuals with obesity, supplementation helped decrease waist circumference and serum insulin levels. In rats on a high-fat diet, it reduced adiposity and improved insulin action. (16).

When and how to take glutamine?

Glutamine can be taken at different times, depending on the desired effects.

• Between meals or every 3 hours to fill anabolic voids. (2-3g)
• During training to regulate the production of ammonia linked to the intake of BCAAs
• After a workout to speed up recovery (2-3g).
• In the evening to limit proteolysis (6 capsules)
• At night to ensure a positive nitrogen balance (6 capsules + 8 capsules of BCAA).

It is recommended to accompany it with a temperate carbohydrate drink.

Synergy

It is customary to believe that a high-protein diet provides a sufficient level of glutamine to meet sports needs. It is however the opposite: the more one consumes proteins, the more the needs in glutamine increase. Indeed, glutamine makes it possible to neutralize the acid released by the amino acids. It is therefore recommended to supplement with glutamine when doing regular sports.

Scientific references

(1) Phillips GC. Glutamine: the nonnessential amino acid for performance enhancement. Curr Sports Med Rep. 2007 Jul;6(4):265-8.

(2) Yan B. Metabolomic investigation into variation of endogenous metabolites in professional athletes subject to strength-endurance training. J Appl Physiol. 2009 Feb;106(2):531-8.

(3) Gleeson M. Dosing and efficacy of glutamine supplementation in human exercise and sport training. J Nutr. 2008 Oct;138(10):2045S-2049S.

(4) Zuhl, M., Dokladny, K., Mermier, C., Schneider, S., Salgado, R., & Moseley, P. (2014). The effects of acute oral glutamine supplementation on exercise-induced gastrointestinal permeability and heat shock protein expression in peripheral blood mononuclear cells. Cell Stress And Chaperones, 20(1), 85-93. doi: 10.1007/s12192-014-0528-1

(5) Raizel, R., & Tirapegui, J. (2018). Role of glutamine, as free or dipeptide form, on muscle recovery from resistance training: a review study. Nutrire, 43(1). doi: 10.1186/s41110-018-0087-9

(6) Khorshidi-Hosseini, M., & Nakhostin-Roohi, B. (2013). Effect of Glutamine and Maltodextrin Acute Supplementation on Anaerobic Power. Asian Journal Of Sports Medicine, 4(2). doi: 10.5812/asjsm.34495

(7) Agostini, F., & Biolo, G. (2010). Effect of physical activity on glutamine metabolism. Current Opinion In Clinical Nutrition And Metabolic Care, 13(1), 58-64. doi: 10.1097/mco.0b013e328332f946

(8) Nava, R., Zuhl, M., Moriarty, T., Amorim, F., Bourbeau, K., & Welch, A. et al. (2019). The Effect of Acute Glutamine Supplementation on Markers of Inflammation and Fatigue During Consecutive Days of Simulated Wildland Firefighting. Journal Of Occupational And Environmental Medicine, 61(2), e33-e42. doi: 10.1097/jom.0000000000001507

(9) Girven, M., Dugdale, H., Owens, D., Hughes, D., Stewart, C., & Sharples, A. (2016). l-Glutamine Improves Skeletal Muscle Cell Differentiation and Prevents Myotube Atrophy After Cytokine (TNF-α) Stress Via Reduced p38 MAPK Signal Transduction. Journal Of Cellular Physiology, 231(12), 2720-2732. doi: 10.1002/jcp.25380

(10) Son, H., Baek, J., Go, B., Jung, D., Sontakke, S., & Chung, H. et al. (2018). Glutamine has antidepressant effects through increments of glutamate and glutamine levels and glutamatergic activity in the medial prefrontal cortex. Neuropharmacology, 143, 143-152. doi: 10.1016/j.neuropharm.2018.09.040

(11) Cruzat, V., Macedo Rogero, M., Noel Keane, K., Curi, R., & Newsholme, P. (2018). Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation. Nutrients, 10(11), 1564. doi: 10.3390/nu10111564

(12) Wang, Z. (2018). Effects of glutamine on intestinal mucus barrier after burn injury. American Journal Of Translational Research, 10(11), 3833-3846.

(13) Darmaun, D., Torres-Santiago, L., & Mauras, N. (2019). Glutamine and type 1 diabetes mellitus. Current Opinion In Clinical Nutrition And Metabolic Care, 1. doi: 10.1097/mco.0000000000000530

(14) Chaudhry, K., Shukla, P., Mir, H., Manda, B., Gangwar, R., & Yadav, N. et al. (2016). Glutamine supplementation attenuates ethanol-induced disruption of apical junctional complexes in colonic epithelium and ameliorates gut barrier dysfunction and fatty liver in mice. The Journal Of Nutritional Biochemistry, 27, 16-26. doi: 10.1016/j.jnutbio.2015.08.012

(15) Niihara, Y., Miller, S., Kanter, J., Lanzkron, S., Smith, W., & Hsu, L. et al. (2018). A Phase 3 Trial of l-Glutamine in Sickle Cell Disease. New England Journal Of Medicine, 379(3), 226-235. doi: 10.1056/nejmoa1715971.

(16) Abboud, K., Reis, S., Martelli, M., Zordão, O., Tannihão, F., & de Souza, A. et al. (2019). Oral Glutamine Supplementation Reduces Obesity, Pro-Inflammatory Markers, and Improves Insulin Sensitivity in DIO Wistar Rats and Reduces Waist Circumference in Overweight and Obese Humans. Nutrients, 11(3), 536. doi: 10.3390/nu11030536