A Quick Guide to Glutamine

True Protein Blog Avatar Fallback reviewed by our Nutrition Team 14 December 2018

A brief guide to the basics and benefits of glutamine. Maintain a healthy immune system whilst promoting muscle growth

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A Quick Guide to Glutamine

What is Glutamine?

Glutamine is a naturally occuring amino acid that is most abundant in the human body. Glutamine is considered to be a conditionally essential amino acid which, means that under certain conditions your body cannot produce enough so it must be provided through the diet, similar to the other nine essential amino acids. Such situation includes times of illness, physical stress such as surgery, trauma and burns, inflammatory disease states like Crohn’s disease and potentially, heavy training loads or prolonged endurance exercise.

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 regard 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 is a part of our performance range and 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 (1):

  1. 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.

  2. 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 on immunoglobulin A (IgA) which provides further protection against bacterial translocation (1).

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 (2).

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 (2).

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 (3,4). These processes include occasions where our skeletal muscle increases the release of amino acids, in particular glutamine and alanine, into our blood circulation (5). 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 if water and some electrolytes in the bowel and so is a successful rehydration strategy (6). These findings warrant the need to investigate if the strategy is also appropriate for rehydration to address exercise induced dehydration.


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Glutamine and medical illness, injury and stress


Specific situations involving illness, injury and stress can lead to a significant decrease in plasma levels of glutamine. When this decrease is severe, it has been associated with increased mortality or death. A scientific review found that glutamine supplementation had a positive effect on the spread of infection and complications within the hospital setting, particularly surgical patients and the critically ill (1).

Other clinical trials have been conducted to look at glutamine supplementation in critical illness, trauma, surgery and cancer. A benefit was shown with regard to mortality rates, length of stay in hospital, and other related illness from infection (1). There is also conflicting studies questioning the benefits in these situations and so research is ongoing.

How is True Glutamine different?

True Glutamine is a premium pharmaceutical grade L-Glutamine sourced from Japan’s Ajinomoto, a global company renowned for premium quality amino acids because they were the first company in the world to manufacture amino acids from natural fermentation processes.

True glutamine contains 100% natural and pure L-glutamine from vegetables, so it’s completely vegan friendly!

How do I take True 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) (7). 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.


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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

IMPORTANT INFORMATION: all content provided here is of a general nature only and is not a substitute for individualised professional medical advice, diagnosis or treatment and reliance should not be placed on it. For personalised medical or nutrition advice, please make an appointment with your doctor, dietitian or qualified health careprofessional.