Last updated: August 27, 2021

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Athletes around the world know just how hard it is to maintain optimal performance in the long run. Unfortunately, stress and injuries can hinder your progress. The good news is that this issue can be fixed by supplementing your diet with glutamine. Keep reading to learn all about glutamine and the amazing benefits it offers.

Glutamine is among the most abundant amino acids found in the human body. Its many functions are vital to our health and well-being. They include strengthening of the immune system, wound repair and development of muscle endurance.


  • Glutamine is an extremely important and abundant amino acid that is found in the human body.
  • The body can synthesise glutamine itself in normal circumstances. Nonetheless, you may need to supplement with glutamine during particularly stressful situations.
  • Glutamine is useful for boosting athletic performance, minimising muscle loss and enhancing immune system strength.

The Best Glutamine: Our Picks

Choosing the right glutamine supplement can be a challenge. To help you get started, we've gathered some of the very best options on the market. These products all offer great value for your money. We hope you'll find something that's just right for you!

Buyer's Guide: Everything You Should Know About Glutamine

Glutamine is one of the most popular sports nutrition supplements found on the market. Most bodybuilders take glutamine to help them gain muscle mass and boost their endurance during training. Glutamine is also commonly used in the field of medicine.

Are you having trouble finishing that last set of your workout? You may be experiencing low glutamine levels.
(Source: Drobot: 45025561/

What exactly is glutamine?

Essential amino acids can't be synthesised by the human body, so they need to be ingested on a daily basis. Glutamine, however, is a non-essential amino acid, which means that the body can create it using other components found in a normal diet. But don't be fooled: non-essential certainly doesn't mean it's not important.

By binding with other amino acids, glutamine can form protein chains that provide structure to your muscles. Experts estimate that 61% of human musculo-skeletal tissue (voluntary muscles) is composed of glutamine, which plays a central role in the growth and repair of body tissues.

Glutamine is frequently mixed into other supplements, such as BCAAs (branched amino acids), electrolytes, minerals, and vitamins.
(Source: Trojanowski: 89190471/

Glutamine is also used as a source of energy by cells found in the liver, intestine, brain, kidney and immune system. Circumstances that impact any of these systems, such as stress, can lead to an uptake in glutamine consumption. That's when you might want to take an extra supply of glutamine with your diet.

What are the functions of glutamine?

Amino acids are formed from atoms of carbon, oxygen, hydrogen and nitrogen. Glutamine, which contains two nitrogen atoms, functions as a transporter of the substance between the blood and cells. Nitrogen itself is a critical molecule for tissue regeneration and growth processes.

Glutamine is also able to pass the hematoencephalic barrier (a protective system that isolates the brain from substances present in the blood). This essentially means that it can exert its function on neurons. These are some of the many functions in which glutamine can play a role:

  • Protein synthesis: Glutamine forms a significant part of muscle and bone tissue, making it essential for anabolism (tissue growth process).
  • PH regulation: Glutamine's ability to release and bring in nitrogen molecules gives it a "buffering" role, protecting the organism from sudden shifts in pH.
  • Non-toxic transport of ammonia: Ammonia is a nitrogen-rich substance that is toxic to humans if it travels freely in the blood. By binding to it, glutamine can transport it safely to the kidneys, where it is then removed.
  • Energy synthesis: This amino acid is as crucial for energy production as glucose is. The cells in the kidney, brain and immune system use it as their primary energy source.
  • Neurotransmitter synthesis: Two neurotransmitters can be synthesised through glutamine: glutamate and GABA (gamma-aminobutyric acid). These two compounds are important for normal brain function.

Keep in mind that these are just a few of glutamine's functions. Recent studies have also linked glutamine to insulin sensitivity, antioxidant synthesis and intestinal permeability regulation. So glutamine is certainly indispensable to a healthy body and mind.

Were you aware that your muscles are harmed during very stressful situations? This process, known as "catabolism," takes place in order to release glutamine into the blood.

Can I be glutamine-deficient?

Experts are split regarding the categorisation of glutamine as a non-essential amino acid. Situations such as stress (physical or emotional), illness, injury and malnutrition can boost your body's demand for glutamine, or limit its synthesis. These are the circumstances in which directly supplementing with glutamine is most helpful.

Caring for another can be very challenging, leading you to use up your glutamine stores.
(Source: Bialasiewicz: 26146754/

Individuals with especially active lifestyles are at the highest risk of suffering a glutamine deficiency. Certain studies, for example, have indicated a noticeable decrease in blood glutamine levels following an hour of intense exercise. While this is normal, the lack of glutamine may pose an issue if any of the following factors are also in play:

  • Diseases: These can be mild (fly, colds, gastroenteritis) or severe (such as cancer). Chronic pathologies like Crohn's disease lead to a loss of glutamine.
  • Allergies: Any state that results in generalised inflammation can contribute to higher glutamine consumption to synthesise immune cells and components of the inflammatory response.
  • Injuries: Glutamine is required for healing injuries. Glutamine needs go up to deal with lesions, burns and fractures.
  • Psychological stress: A psychologically stressful situation (like preparing for a big test) generates an increased expenditure of glutamine to form neurotransmitters.
  • Poor nutrition: "Magic" diets can be too restrictive, resulting in an insufficient intake of amino acids. Individuals who combine intense exercise with a nutrient-poor diet are at high risk of a glutamine deficiency.
  • High intensity exercise: Professional athletes and fitness junkies often present an increased need for glutamine. Their constantly growing muscles require more energy than that of others.

What are the symptoms of a glutamine deficiency?

Normal blood glutamine levels are about 600 ɥmol/L. Unwanted symptoms may begin to appear when you fall below that value. Levels under 200 ɥmol/L are a sign of a severe illness. You should be sure to monitor your glutamine levels if you experience any of these symptoms:

  • High occurrence of infections: Glutamine is required for maintaining a strong immune system. A deficiency will result in a higher prevalence of all kinds of infections.
  • Fatigue: If your glutamine levels are too low, your muscles won't be able to transform it into energy. Muscle endurance will decrease in turn, leaving you at risk of feeling especially tired after training.
  • Poor wound healing processes: Without sufficient glutamine, it's hrader for your cells to replicate, which then prevents normal wound healing.
  • Loss of muscle mass: Keep in mind that 60% of your muscle tissue is glutamine. When you have deficient levels of glutamine, your body "breaks" muscle fibers to acquire glutamine, thereby decreasing muscle mass.
  • Gastrointestinal problems: Intestinal cells use glutamine for nutrition, growth and development. Your digestion and nutrient absorption capacity can be affected by a glutamine deficiency.
  • Weight loss: The loss of muscle mass, combined with malabsorption of food, can result in unwanted and unhealthy weight loss.

A glutamine molecule: l-glutamine, Gln, Q.
(Source: Molekuul: 85933780/

Glutamine deficiencies have also been linked to two especially unpleasant conditions. Firstly, the overtraining syndrome (OTS) is a decline in sports performance associated with fatigue, irritability and loss of muscle mass that occurs in people whose training intensity is too high.

Secondly, there is "leaky gut syndrome." This condition indicates that intestinal cells are allowing toxic molecules, microorganisms and undigested food particles to pass into your blood. This results in a state of chronic inflammation alongside abdominal discomfort, swelling and weight loss.

How can I raise my glutamine levels?

Those who have generally sedentary lifestyles can increase their glutamine levels simply by sticking to a healthy diet that's rich in nutrients and antioxidants. Diets that are too limited or too high in fat can decrease the available glutamine, which your body will utilise to detoxify itself of these substances.

Meanwhile, if you're a very active person, a good diet may not be sufficient. Avoiding mental and emotional stress, lack of sleep and overtraining will help you maintain normal glutamine levels. Taking a glutamine supplement may also be useful in such conditions.

Diets high in saturated fat and protein have been shown to lower glutamine levels by up to 25%.

Which foods contain glutamine?

Glutamine is found in foods of animal origin, including meat (preferably lean), eggs and dairy products. You'll also find glutamine in some fruits, vegetables, legumes, and soy derivatives. Here are some glutamine-rich foods:

  • Meat: Veal, fish, pork and poultry
  • Dairy: Milk, yoghurt and cheese
  • Vegetables: Eggplants, spinach, cabbage and carrots
  • Fruits: Papaya, miso and beans
  • Others: Tofu

Keep in mind that the glutamine present in these foods is broken down when cooked, which means that your body can't absorb it as efficiently. So if you're looking to boost your glutamine intake, try consuming these foods in raw, cured or smoked form. A healthy diet normally provides about 3-6 grams/day of glutamine.

Meat and dairy products are excellent sources of glutamine when consumed raw, smoked, or cured.
(Source: Baibakova: 85027893/

What kinds of glutamine supplements are available?

You should know that glutamine has a very low absorption. The enterocytes (intestinal cells) and white blood cells of the intestinal tract consume most of this amino acid, which means you should look for a supplement that specifically facilitates glutamine absorption. There are two primary kinds:

  • L-glutamine supplements: This is the active form of glutamine (unlike D-glutamine, which is an inactive compound that isn't used in nutrition). This molecule comes in powder, tablet or capsule form. Its effect goes away if added to other foods (like protein bars).
  • Glutamine peptides: These supplements are more difficult to absorb than L-glutamine, but they're more stable and can be mixed into bars or processed drinks. These peptides may appear as "L-alanyl-L-glutamine" or "glycyl-L-glutamine" on the ingredient list of some supplements.

L-glutamine is the most bioavailable form of glutamine, which means that it's easier for the body to absorb. Nonetheless, many prefer a supplement that can be taken with protein bars or ready-to-drink beverages. If that's the case for you, we recommend a product that has glutamine peptides as a primary ingredient.

J.J. Ashton Registered Holistic Nutritionist
"Glutamine is postulated to provide benefits to weight, exercise recovery and bowel disorders, but more research is needed to understand its role in these conditions."

How do I take a glutamine supplement?

These kinds of supplements have around for years, in the fields of health and sports. Putting aside the glutamine used in medical practice (diets for those with burns, cancer or HIV), there are three ways of taking glutamine:

Supplementation routine Dose Advantages Disadvantages
L-glutamine ("free" glutamine) 5-10 grams one or two hours prior to meals. Best in the morning or before training. Easy digestion. It can be mixed with drinks rich in electrolytes (sodium and potassium) to boost absorption. Poor bioavailability (30%). It loses effectiveness when mixed with hot or acidic drinks. Foods limit its absorption.
Glutamine peptides (non-free glutamine) 10 grams during the day, with meals or post- training. Convenient: it can be taken with meals. Easily carried in the form of bars or shakes. Very poor bioavailability (20%). A higher dose is needed for effective absorption.
L-glutamine + glutamine peptides 5-10 grams of L-glutamine and glutamine peptides in total, taking into account the characteristics of each product. Divide into different doses throughout the day. L-glutamine is easier to digest and absorb before training. Glutamine peptides can be taken after training and with meals. Adaptable supplementation at any time of the day. It can be hard to evaluate the total dose of glutamine ingested. More costly in the long run (you have to purchase two supplements).

The kind of supplementation you choose will depend on personal preferences, schedule and budget. But be aware that all have proven helpful in improving athletic performance and alleviating gastrointestinal discomfort.

What are the benefits of using glutamine supplements?

Although many people consider glutamine supplements as only a way to increase muscle mass, this isn't the full story. The muscle gain linked to glutamine intake is actually indirect: a sufficient intake of this amino acid ensures that your muscle isn't destroyed in order to feed other cells.

You'll get a number of health benefits from maintaining healthy glutamine levels.
(Source: Undrey: 48565581/

The reality is that the true potential of glutamine lies in long-term consumption. Those who use glutamine supplements insist that they benefit from an improvement in their physical, intellectual and mental states. Here are some reported benefits:

  • Reduction in inflammation: Glutamine helps intestinal cells form an effective barrier against toxins found in the digestive tract. The intensity of allergic reactions and inflammatory processes is then reduced.
  • Improvement of bowel transit: Healthy enterocytes can absorb essential nutrients and dispose of unnecessary ones. This results in improvement regarding intestinal discomfort, gas and abdominal swelling.
  • Ulcer repair: Some studies have indicated that glutamine supplementation is associated with faster healing of gastric ulcers.
  • Mood improvement: Were you aware that up to 80% of neurotransmitters are formed in intestinal cells? By taking glutamine, you allow these cells to have sufficient energy to produce serotonin, an important mood regulator.
  • Enhancement of physical performance: A boost in energy reserves allows you to exercise for longer. It also helps you to avoid overtraining syndrome, meaning you can train at a high enough intensity to boost your muscle mass.
  • Strengthened immune system: Stress or strenuous physical exercise can weaken the immune system and increase the possibility of infection. Glutamine combats this phenomenon, resulting in the strengthening of cells in your immune system.
  • Fat loss: This supplement appears to limit the desire to consume alcohol and sugary foods, leading to healthy weight loss.

Are there any side effects from taking glutamine?

Glutamine is generally considered to be safe even at very high doses. In the medical field, doses of up to 30 grams per day are given intravenously without producing significant side effects. Reports have indicated heightened blood ammonia levels while taking high doses of glutamine, but this does not pose a threat to healthy individuals.

Nonetheless, glutamine supplementation may cause heartburn, bowel discomfort and nausea. If that occurs, try dividing your dose into smaller doses (about 5 grams) throughout the day, until you adjust to the desired concentration. Consuming glutamine without sweeteners may also limit any side effects.

Dr. Josh AxeNaturopathic Doctor, Co-founder of Ancient Nutrition
"Although the effects of excess glutamine rarely cause problems, if you are taking oral glutamine long-term, it’s a good idea to also supplement with B vitamins. This especially applies to vitamin B12, which controls glutamine buildup in the body."

In some very rare cases, cardiac and vascular alterations related to glutamine consumption were observed. Some individuals who suffer from joint pathologies saw a worsening of their joint pain after consuming glutamine. There have also been reports of edema associated with the intake of glutamine.

What are the contraindications of glutamine supplements?

As we mentioned above, glutamine supplements are generally very safe for healthy individuals. Still, people with unique health conditions should be careful when supplementing with this product. Always consult your doctor prior to purchasing and beginning a glutamine supplement if you have any of these conditions:

  • Diabetes: Glutamine is essential for glucose generation. People with diabetes may see a rise in blood glucose (blood sugar) following glutamine supplementation.
  • Bipolar disorder: Glutamine supplementation has been shown to destabilise the mood of individuals with this psychiatric disorder in some instances.
  • Pregnancy and lactation: There is not sufficient data to determine whether glutamine is safe for the fetus or infant, so it is advised to avoid this supplement during pregnancy and lactation.
  • Cirrhosis: An unhealthy liver may not be able to properly metabolse the ammonia generated following glutamine intake.
  • Renal disease: A deterioration of renal insufficiency has been seen in elderly people who took glutamine supplements.

Finally, we should mention a controversial claim regarding glutamine, which is that it can fight cancer. It is true that some doctors administer glutamine to address the malnutrition that sometimes occurs during treatment for cancer.

Nonetheless, other experts suggest that glutamine acts as an additional source of nutrition and energy for tumor cells, encouraging their growth. We recommend that you consult a health professional before making decisions that may have a significant impact on your health.
"The most important thing to consider when selecting a glutamine product is the delivery system. If you're purchasing a powder, capsule or tablet, then free form L-glutamine works best. However, because glutamine is unstable, avoid read-to-drink beverages or protein bars claiming to contain supplemental L-glutamine."

What do scientific studies say about glutamine supplementation?

We've been discussing many different benefits of glutamine supplements. But you may be wondering if there is scientific evidence to corroborate all of this. Data does exist to confirm the benefit of glutamine in serious pathologies (such as deep burns or HIV).

However, there is no concrete evidence indicating that glutamine is an efficient food supplement. The amino acid has largely gained popularity as a sports supplement due to the positive results seen by fitness lovers, but scientific evidence cannot back up these experiences.

In favor Against
Proven efficacy in some diseases. Latest studies (2018) find no significant boost in sports performance or muscle mass gain.
Useful for weight loss. Less effective for weight loss than other supplements (such as L-carnitine).
Safe supplement, even at high doses. It can increase blood glucose and ammonia levels.
Affordable and easy to find. Similar supplements exist with proven clinical benefits (such as creatine).
Consumers report an improvement in their overall long-term condition. These subjective benefits cannot be scientifically proven.

At the end of the day, taking a glutamine supplement is your personal decision. This product has been used by elite athletes for decades, and they report good results. Although proven benefits of this supplement have not been found for healthy individuals, it does seem to have a positive impact on the health of those who suffer from glutamine deficiency.

Shopping Criteria

Supplements that are commonly used by athletes tend to have particularly eye-catching labels that lack objectivity, which can your purchasing decision very difficult. In the next section, we've outlined the most important factors to consider when picking your glutamine supplement, to help you find the right product for your needs.

Allergies and Intolerances

You should be aware that glutamine supplements are frequently produced in locations that also handle nuts, animal products, lactose and gluten. If you're intolerant to any of those, be sure the brand you pick uses neutral glutamine, preferably in powder form and with high purity.

On the other hand, if you're looking to supplement with glutamine in order to improve a gastrointestinal condition like peptic ulcers, it is advised to pick products that are free of sweeteners. Sweeteners can negatively impact the intestinal flora, thereby harming your gastrointestinal health.

Pharmacological Interactions

Glutamine is a supplement with very few drug interactions. Nonetheless, it can affect the function of medications that lower ammonia (lactulose) levels, chemotherapy treatments, and anti-epileptic medicine. Make sure to consult with your doctor if you're taking any of these medications.

Vegan or Vegetarian Diet

There are several supplementation brands that produce glutamine free from animal products. Although powder is normally the safest option for vegans and vegetarians, you'll also find some vegan-friendly capsules. Just make sure to look for the vegan seal of quality on the packaging!

Combination With Other Supplements

Although glutamine is best absorbed on its own, it is increasingly rare to find this amino acid by itself in a supplement. Manufacturers seem to prefer combining it with other supplements. Here are some of the most common supplements that are combined with glutamine:

  • BCAA: Branched chain amino acids, together with glutamine, contribute to muscle maintenance and the reduction of post-training fatigue.
  • Citrulline: When combined with glutamine, this nutrient stimulates the production of nitric oxide, a vasodilator that increases the arrival of oxygen to the muscle, thereby supporting recovery and growth of muscle fiber.
  • Alpha-ketoglutarate: This compound appears to reduce the degradation of glutamine, boosting its effectiveness. It also contributes to antioxidant synthesis.
  • N-acetylglucosamine: This compound boosts the effectiveness of glutamine supplements while preventing the increase in blood glucose that is a frequent consequence of glutamine supplementation.

Value for Money

Most manufacturers suggest taking low doses of glutamine to prevent the intestinal discomfort that can result from ingesting this substance.

Still, keep in mind that the most beneficial effects of glutamine tend to appear with relatively high doses (10-15 grams of glutamine).

It is therefore recommended to look for supplements that offer high concentrations of glutamine. You may want to look for savings packs or larger-quantity containers, but be sure to check the expiration date!

Form of Administration and Dose

As we mentioned earlier, glutamine is found in powder or capsule form. Capsules are a clean and convenient option, but you may need to take more in order to get a high dose. Glutamine powder, on the other hand, is much easier to dose.


Glutamine is one of the most important amino acids for our body, since it makes up muscles and is used as fuel for neurons, enterocytes and lymphocytes. Stress and illness can impact our normal glutamine reserves, causing a loss of muscle mass and abdominal discomfort.

Glutamine can help you stay strong, even in the toughest times. If you're looking to maintain good health despite the stresses of life, then glutamine may be your best ally. Now you know that it's much more than just a bodybuilding supplement!

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(Source of featured image: Evgeniy Losev: 84109618/