When to Take Glutamine?

  • 1st Revision: Tamsin Rose
  • 2nd Revision: Pranitha Ven Murali[Linkedin]
  • 3rd Revision: Kaamya Mehta[Linkedin]

Introduction – the function of amino acids 

Amino acids are one of the vital molecules that are the building blocks of proteins in the body. Such proteins are particularly important for muscle growth, muscle tissue strengthening and repair. In total, there are 20 different amino acids in the body, twelve of which are non-essential and made in the body whilst the remaining eight essential amino acids can only be obtained through diet or supplements. A deficiency in these amino acids could lead to poor digestion and increased stress. Glutamine is best to take after a workout to optimise protein synthesis and improve immune function.

What is glutamine?

Glutamine is the most abundant amino acid in the body, mainly functioning to build up protein. It is the most versatile due to its genetic makeup as it functions highly in the digestive and immune systems. In the body, glutamine is made by the molecule glutamate which reacts with ammonia and ATP molecules (energy). The formation of glutamine is regulated by glutamine synthetase catalyst which speeds up and regulates a reaction. Glutamine is also important for making more essential amino acids and glucose which is vital for respiration to occur. As mentioned before, glutamine aids the production of muscle tissue and is important for immune system functioning and for the digestive system. Glutamine can be found in 2 ways. These are L-glutamine and D-glutamine. The L-glutamine variant is the type to work in the main mechanisms in the body.(1)

Why is glutamine important to your health? 

The intake of glutamine supplements is not a new concept. For years, patients suffering from sickle cell disease, burns, obesity and lung cancer have been taking supplements to relieve symptoms. Recent scientific studies have also suggested that a lack of amino acid intake in the diet can lead to anxiety, depression, insomnia and general fatigue and weakness due to lack of strength from reduced muscle tissue. Therefore, taking glutamine supplements could be vital to improve these symptoms. Moreover, glutamine and other amino acids are important for production and functioning of neurotransmitters and hormones which if left unbalanced can result in weight problems. Glutamine also enhances gut health as it holds upto 70% of the total immunity, thus can aid with the prevention of certain illnesses or disease. Glutamine can mainly come from nutritious foods such as leafy vegetables, beans, protein (meat from animals) and most dairy products. However, for people mostly on a vegan or vegetarian diet, these options may not always be possible and can resort to glutamine supplementation.(2) 

When should you take glutamine? 

To optimise glutamine in the body, the best time for glutamine intake tends to be post workouts and before a big meal. This is to help with muscle recovery after an intense workout, increases muscle tissue strength and decreases muscle soreness. To retain more muscle in the body, there needs to be a constant high supply of nitrogen, and thus glutamine can aid the recovery.

Previous studies have shown that glutamine administered orally (oral glutamine) over a period of time were found to have increased plasma glutamine. This means that the volume of glutamine in the blood was high, thus allowing it to reach the muscles and prevent soreness. Moreover, after taking patients’ venous blood samples, it was found that oral glutamine administration also increased the amount of growth hormone in the plasma of the blood – ultimately demonstrating that glutamine elevates growth hormone. Growth hormones are particularly important for cell reproduction, regeneration and muscle growth.(3) 

Some people with glutamine deficiencies may also take supplements. This includes people with severe illnesses such as obesity or those recovering from surgeries and need it for muscle recovery and their immune systems. 

How to take glutamine?

Administration of glutamine can be done in many forms – the most popular being oral glutamine. L-glutamine supplements can be purchased at most health & wellness stores. These can come in the form of tablets which are taken once a day to maintain the structure of muscle tissue, hair and nails. Tablet supplements are mostly taken by those with illnesses or recovering from surgery. In sports nutrition, glutamine powder is used instead. Glutamine powder tends to have 5-10g of glutamine in every serving which is the recommended amount according to research in the journal of nutrition. 

Consumers of glutamine powder must carefully curate their own recommended amount of powder depending on how much exercise you do. Some athletes who do high amounts of exercise tend to take more powder as glutamine concentration tends to deplete during exercise. Powders should be mixed with water to ensure hydration. Recently, social media trends suggested that dry scooping and administering powder without diluting it with water would make more of an impact. However, both doctors and scientists have said that dry scooping is dangerous and does not have any more health benefits than diluting. Ultimately, it is always best to read the instructions before consuming. 

As mentioned previously, glutamine is not made by the body and so must be consumed either by supplementation or food. These foods can be fish, eggs, dairy, whey (which can also be supplemented with whey powder) and casein. For vegetarians and vegans these foods can be beans, tofu, lentils, spinach and cabbage.(4) 


Even though glutamine is the most abundant amino acid in the body, it must be regulated, and frequent intake can ensure optimum health. This means having to eat the correct foods or diet. If this is not possible, or there is a need for quicker glutamine absorption in the body for exercise, then supplements can be taken. Without glutamine, the body risks the lack of skeletal muscle strengthening and formation, muscle soreness and breakdown and a lack of muscle protein synthesis. All of this could result in tiredness and a general feeling of fatigue and weakness. To summarise, supplements can be taken before or after intense exercise or recovering from surgery to help with muscle building. But overall, it is up to the person to decide whether they want to supplement with tablets, powder or food. 


  1. Lopez MJ, Mohiuddin SS. Biochemistry, Essential Amino Acids. In: StatPearls [Internet]. StatPearls Publishing; 2022.
  2. GLUTAMINE: Overview, uses, side effects, precautions, interactions, dosing and reviews [Internet]. Webmd.com. [cited 2022 Jul 19]. Available from: https://www.webmd.com/vitamins/ai/ingredientmono-878/glutamine
  3. Cruzat V, Macedo Rogero M, Noel Keane K, Curi R, Newsholme P. Glutamine: Metabolism and immune function, supplementation and clinical translation. Nutrients [Internet]. 2018 [cited 2022 Jul 19];10(11):1564. Available from: http://dx.doi.org/10.3390/nu10111564
  4. No title [Internet]. Oup.com. [cited 2022 Jul 19]. Available from: https://academic.oup.com/jn/article/138/10/2045S/4670120
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Thanucha Sooriapatham

Master of Science - MS, Science communication student, The University of Sheffield, England
Thanucha is a BSc (Hons) Pharmacology and Physiology graduate with a strong interest in journalism, scientific content writing, and editing.
She completed and passed MCB80.3x: Fundamentals of Neuroscience, Part 3: The Brain - a course of study offered by HarvardX, an online learning initiative of Harvard University.

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