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What is glutamine?

medico-author

Written byMedico Digital

julie_cunningham

Reviewed byJulie Cunningham

glutamine supplements powder form
Ready to level up your protein game? Enter glutamine, the all-star amino acid that’s got everyone talking. Whether it’s boosting recovery or supporting immunity, let's see what it’s all about

Summary

1What does glutamine do?

Glutamine is the most abundant amino acid in the body…

2Potential benefits of glutamine

Glutamine supplementation has been linked to several possible health benefits, though it’s important to note that…

3Glutamine side effects

Generally, glutamine supplements are well tolerated in adults. However, this doesn’t mean everyone should take them…

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Glutamine is one of the most abundant amino acids, playing a key role in various body functions including digestion, immunity, and more.1 While research continues to explore its full effects, many people are curious about how it might support their wellbeing (and if you’ve made it this far, you might be one of them). 

So, before you consider adding glutamine to your routine, let’s explore what it does, its potential benefits and any side effects to watch out for.

What does glutamine do?

Glutamine is the most abundant amino acid in the body.1 You might already know that amino acids are ‘building blocks’ used to make proteins. The body then uses these proteins to help support your musclesimmune system and digestive health, for example.

Glutamine is one of 20 amino acids.2 Your body can produce some of these amino acids itself, but others you may need to get from your diet.2 You can also get glutamine through certain foods, like bone brotheggsyogurttofu, and leafy greens (like spinach).

However, there can be times when you experience a glutamine deficiency or you feel that you need to boost the levels of this amino acid – for example, after illness or surgery.2 

There are two types of glutamine – L-glutamine and D-glutamine.1 The most important one to know about is L-glutamine, since it’s used to make proteins and perform other important functions in your body. 

D-glutamine, on the other hand, seems to have little to no effect on the way our bodies work.1

Think the potential benefits could be for you? It’s best to get L-glutamine through your diet where you can, but you can also take supplements – they’re readily available and easy to take. Let’s find out more…

What are the potential benefits of glutamine?

Glutamine supplementation has been linked to several possible health benefits, though it’s important to note that the research is still in its early stages. Many of the studies conducted have been small, and the overall evidence is mixed. 

That said, glutamine supplements might offer some potential perks, such as: 
  • removing excess ammonia (waste products/toxins) from the body 3 
  • supporting your immune function – some immune cells use glutamine as a source of energy 1
  • supporting the digestive system – glutamine is an energy source for intestinal cells such as enterocytes, which are cells involved in the uptake and absorption of nutrients
While these benefits are promising, further research is needed to confirm glutamine’s full impact on health.

Glutamine sources: where can you get it from?

Around 80% of your body’s glutamine can be found in your muscles. Your body can make as much glutamine as it needs to function correctly all by itself.1 You can also boost your natural levels of this amino acid by adding foods that are high in glutamine into your diet. 

Food sources containing high levels of glutamine include plant and animal proteins like beef, pork, poultry, milk, yoghurt, ricotta cheese, raw spinach and cabbage. A considerable amount of glutamine also comes from refined grains, whole grains and cereals.

Finally, you can consider taking L-glutamine supplements as an easy and convenient way of boosting your glutamine levels. 

Alternatively, you could look at taking a comprehensive amino acid supplement that contains the recommended amounts of all amino acids, including L-glutamine. These are available in both tablet form and as powders in a variety of flavours. You can add them to drinks, such as shakes and smoothies, as well as to things like porridge and pancakes.
Sport food supplement powder with natural beige background and props. Supplement, creatine, hmb, bcaa, amino acid or vitamine in a white scoop. Sport nutrition concept... Check my profile for more!

Glutamine dosages

Exactly how much glutamine you need will depend on your individual circumstances and reasons for taking supplements. 

Nevertheless, we recommend that you consult with your healthcare practitioner before you start taking glutamine supplements.

Are there any side effects of glutamine?

Glutamine supplements are generally well tolerated in adults. However, this doesn’t mean everyone should take them.5 Studies show that glutamine supplements shouldn’t be consumed by people with kidney disease, liver disease or a rare childhood disorder called Reye’s syndrome.6-8 

Taking any sort of supplement can cause side effects and glutamine is no exception. Some of the side effects associated with routinely taking glutamine include:9
  • bloating
  • nausea 
  • dizziness 
  • heartburn 
  • stomach pain 
 Doses of up to 0.65g of glutamine per kg of body mass have been reported to be tolerated without resulting in significant side effects.However, the typical dose of glutamine used in muscle recovery studies is around 0.1g of glutamine per kg of body weight per day.10 This means that while 0.65g per kg of body weight may have been tolerated, generally, a lower dose is given when scientific research is carried out.10

Studies on the effects of glutamine, especially taken in high doses for an extended period, are limited. This means that we don’t know exactly what impact it could have on your body long-term.

If you’re considering starting any supplement, you must check to make sure it doesn’t interact with any other medication (prescription or over-the-counter) you take. No formal drug interaction study has been done with glutamine, so we recommend you speak to your healthcare provider before taking your first dose.

The final say

Glutamine could be a helpful addition to your wellness routine, potentially supporting everything from muscle recovery to immune function. But while the research shows promise, there’s still more to learn. 

Want more info on supporting your immune and digestive health? Discover our immunity guide or browse our favourite gut health products.

If you're thinking of adding glutamine to your daily mix, it might be worth considering – just remember to check in with your health professional first.

Disclaimer

This article provides informational advice and is not a substitute for medical care. Curated by experts for accuracy, we take great care to ensure the information is up-to-date and relevant. However, you should always consult your GP or healthcare professional before using supplements or alternative products, particularly if you have medical conditions or are under supervision.

While we strive for accuracy and balance, please be aware that this article may discuss products available for purchase through Holland & Barrett. Consult a healthcare professional before making any health-related decisions.

Please note scientific evidence for this topic is very limited and although there are emerging studies, more clinical research needs to be conducted. Please speak to your GP before taking any new products.
 

Sources

  1. Cruzat V, et al. Glutamine: Metabolism and immune function, supplementation and clinical translation. Nutrients. 2018;10(11):1564. https://doi.org/10.3390/nu10111564 
  2. British Nutrition Foundation. Protein [Internet]. [cited 2024 Jul 4]. Available from: https://www.nutrition.org.uk/nutritional-information/protein/ 
  3. Hakvoort TBM, et al. Pivotal role of glutamine synthetase in ammonia detoxification. Hepatology. 2017;65(1):281–93. https://doi.org/10.1002/hep.28852 
  4. Kim M-H, Kim H. The roles of glutamine in the intestine and its implication in intestinal diseases. Int J Mol Sci. 2017;18(5):1051. https://doi.org/10.3390/ijms18051051 
  5. Garlick PJ. Assessment of the safety of glutamine and other amino acids. J Nutr. 2001;131(9):2556S-61S. https://doi.org/10.1093/jn/131.9.2556S 
  6. Glutamine Information | Mount Sinai - New York [Internet]. Mount Sinai Health System. https://www.mountsinai.org/health-library/supplement/glutamine 
  7. Simón J, et al. Glutamine, fatty liver disease and aging. Aging (Albany NY). 2021;13(3):3165–6. https://doi.org/10.18632/aging.202666 
  8. Holecek M. Side effects of long-term glutamine supplementation. JPEN J Parenter Enteral Nutr. 2013;37(5):607–16. https://doi.org/10.1177/0148607112460682 
  9. Gleeson M. Dosing and efficacy of glutamine supplementation in human exercise and sport training. J Nutr. 2008;138(10):2045S–2049S. https://doi.org/10.1093/jn/138.10.2045S 
  10. Ramezani Ahmadi A, Rayyani E, Bahreini M, Mansoori A. The effect of glutamine supplementation on athletic performance, body composition, and immune function: A systematic review and a meta-analysis of clinical trials. Clinical Nutrition. 2019 Jun;38(3):1076–91. https://www.clinicalnutritionjournal.com/article/S0261-5614(18)30173-0/abstract
 

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