L-Glutamine, also known as simply glutamine, is an essential amino acid produced in the human body, and is essential for proper function of the immune system, brain, and digestive system. However, at certain times L-Glutamine ingestion via dietary or supplement intake is necessary to sustain normal L-Glutamine levels as the body cannot naturally make enough to do so. 

It is stored in both muscles and blood plasma, and is found mainly in skeletal muscle. It exists in 61% of your skeletal muscle, it also consists of 19% nitrogen, making it the primary transporter of nitrogen into your muscle cells. L-Glutamine plays an important role in nitrogen balance and protein synthesis in bacteria and the small intestine, which is why it is so highly recommended in the health and supplement community.

What Foods Contain Glutamine?

As glutamine is an amino acid it acts as a building block of protein and it is found in common protein foods as well as some plant-based foods. 

Good sources of glutamine are found in:

  • Beef
  • Pork
  • Chicken
  • Eggs
  • Dairy milk
  • Goat’s milk and cheese
  • Yoghurt
  • Cottage and ricotta cheese
  • Whey protein
  • Casein protein
  • Corn
  • Rice
  • Spinach
  • Cabbage

  • Glutamine can also be supplemented in the diet as L-Glutamine in powder form.

    What Is The Difference Between Glutamine And L-Glutamine?

    The terms Glutamine and L-Glutamine is often used interchangeably in most of the information you will come across in regards to sports performance.

    The difference is within the chemical structure. L-Glutamine is an isomer of glutamine which means that it has a slightly different arrangement of atoms as a molecule. Our body can produce L-Glutamine and it is also found in food and in its isolated form as a dietary supplement.

    Why Is Glutamine Important And What Are The Benefits?

    Glutamine plays an important role in multiple physiological functioning of our bodies in a healthy state at rest, during strenuous physical exercise and periods of illness and disease. 

    Glutamine And Gut Health

    Glutamine is the preferred fuel source of our gastrointestinal cells that are responsible for maintaining its structure and reducing gut mucosal atrophy which, is a physical change of the intestinal cells that can cause:

    Intestinal Permeability - how easily substances (like water, electrolytes and waste products) can pass through the walls of our intestines into our bloodstream and other areas of the body.

    Bacterial Translocation - movement of bacteria through the intestinal wall to other sites including those considered sterile such as internal organs and our bloodstream. Glutamine also has a positive effect on the secretion of immunoglobulin A (IgA) which provides further protection against bacterial translocation.

    Both intestinal permeability and bacterial translocation can have a negative and serious impact on our overall health.

    Glutamine, Immunity And Sports Performance

    Glutamine plays a vital role in maintaining a healthy immune system and recovery. Our immune system defenses can be reduced with chronic high intensity training making us more susceptible to illness such as the common cold and other respiratory tract infections.

    Prolonged exercise like a marathon-type event can deplete blood glutamine concentrations by 20%. One study reported that marathon runners had a significantly lower incidence of upper respiratory tract infection symptoms (32%) after seven days following their event when supplementing 5g glutamine compared with the placebo group.

    Glutamine And Other Sports Performance Benefits

    From a sports performance perspective, intestinal permeability increases as a response to high intensity exercise and long-term, a rise in catabolic processes. These processes include occasions where our skeletal muscle increases the release of amino acids, in particular glutamine and alanine, into our blood circulation. Catabolism can also occur from starvation. Reducing and preventing catabolism is important to maintain muscle mass and prevent your body from breaking it down to be utilised as a fuel source in various cellular processes.

    Glutamine has been shown to assist in the absorption of water and some electrolytes in the bowel and so is a successful rehydration strategy.

    How Do I Take Glutamine?

    Glutamine appears to be most beneficial for maintaining a healthy immune system, optimal gut functioning and supporting strenuous exercise. Therefore optimal dosage for each individual will vary. 

    Industry standards for L-Glutamine is 5g daily. There is evidence to show no ill effect with dosages up to 14g daily in healthy adults and so this is considered the Observed Safe Level (OSL). Whilst glutamine does appear to have a number of benefits, there is little research in relation to the effects of glutamine in large doses for a long period of time. We advise that you stick to the recommended serving size or seek guidance from your doctor or Accredited Sports Dietitian.


    McRae MP. Therapeutic benefits of glutamine: An umbrella review of meta-analyses. Biomed Rep. 2017;6(5):576-584.

    Gunzer W, Konrad M, Pail E. Exercise-induced immunodepression in endurance athletes and nutritional intervention with carbohydrate, protein and fat-what is possible, what is not?. Nutrients. 2012;4(9):1187-212.

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

    Éder Ricardo Petry, Vinicius Fernandes Cruzat, Thiago Gomes Heck, Paulo Ivo Homem de Bittencourt Jr., and Julio Tirapegui. L-glutamine Supplementations Enhance Liver Glutamine-Glutathione Axis and Heat Shock Factor-1 Expression in Endurance-Exercise Trained Rats. International Journal of Sport Nutrition and Exercise Metabolism 2015 25:2, 188-197.

    He Y, Hakvoort TB, Köhler SE, et al. Glutamine synthetase in muscle is required for glutamine production during fasting and extrahepatic ammonia detoxification. J Biol Chem. 2010;285(13):9516-24.

    Gutiérrez C, Villa S, Mota FR, Calva JJ. Does an L-glutamine-containing, glucose-free, oral rehydration solution reduce stool output and time to rehydrate in children with acute diarrhoea? A double-blind randomized clinical trial. J Health Popul Nutr. 2007;25(3):278-84.

    Shao A1, Hathcock JN.Risk assessment for the amino acids taurine, L-glutamine and L-arginine. Regul Toxicol Pharmacol. 2008 Apr;50(3):376-99. Doi: 10.1016/j.yrtph.2008.01.004. Epub 2008 Jan 26.