Difference Between Glutamine and I Glutamine

What is glutamine?

Amino acids are the building blocks of protein synthesis in the body. To maintain an optimal function of one’s health, it is important to get adequate protein. The essential proteins required by our body are produced by 20 essential and nonessential amino acids. Non-essential amino acids can be synthesized within the body and are not required to be included in the diet. On the contrary, essential amino acids can only be obtained through diet. Glutamine is an important and most abundant non-essential amino acid found in our body, that acts as the building block of protein and primarily helps in intestinal health and liver detoxification. Glutamine is produced in muscles and supplied to different parts of the body through blood circulation. Glutamine is considered to be the non-toxic way of excreting ammonia from blood. Two major storage sites of glutamine in the body are skeletal muscles and liver.

L-glutamine, the difference between glutamine and L-glutamine?

In general, glutamine and L-glutamine are considered to be the same but in scientific terms, glutamine is the amino acid whereas L-glutamine is an isomer of glutamine. Isomers are molecules that have the same substituent atoms that are assembled in a different way. There are two isomers of glutamine amino acid, L-glutamine and D-glutamine, where L-glutamine is the most common non-essential amino acid found in muscles and helps in various essential body functions. L-Glutamine is chemically synthesized from ammonia and glutamic acid in the presence of glutamine synthetase.

Importance of glutamine and dietary sources

Glutamine is present in blood circulation, supplying several types of cells throughout the body that are found to be dependent on glutamine. Glutamine acts as a cell’s energy source, helping in nitrogen transport throughout the body. Other cells rely on glutamine to function properly.  For example, lymphocytes or white blood cells use glutamine as fuel, while the brain uses it to create neurotransmitters and other essential proteins.

There are two sources of glutamine supply to the body, it can be either internally synthesized or externally consumed. Even though glutamine is termed as a non-essential protein and can be synthesized within the body cells, certain illnesses, such as fever or infection, might result in overuse of white blood cells thereby increasing the demand for glutamine. The demand surpasses the internal supply, and in those cases, glutamine is obtained through the diet, or, more rarely, through enteral supplementation. Considering how vital glutamine is for human functioning, researchers demand it to be classified as a conditionally essential amino acid.

Glutamine can be externally supplied to the body by altering a diet to include certain foods and dairy products that are rich in ammonia content:

  • Tofu
  • Lentils
  • Peas
  • Cabbage
  • Beetroot
  • Beans
  • Spinach
  • Parsley
  • Beef 
  • chicken
  • Eggs
  • Fish
  • Milk
  • Cheese

Glutamine and intestinal health

Glutamine is abundantly synthesized and stored in muscles and the liver. Glutamine primarily supports intestinal health, boosting immunity, promoting immune cell activity in the gut and preventing infection and inflammation in the intestinal area. The intestinal tissues use glutamine as their energy source to maintain proper intestinal barrier integrity and reduce intestinal spasms.

Effects of glutamine in muscle gain and exercise performance

Glutamine is extensively used in sports nutrition due to its immunomodulatory and anti-fatigue role. Studies suggest [2,3] that glutamine supplementation, alone or associated with other nutrients, delays muscle fatigue and increases physical exercise performance. Glutamine is also found to help prevent muscle loss In cancer patients and patients suffering from AIDS/HIV. In these cases glutamine boosts protein synthesis that is reduced in cancer and AIDS/HIV, preventing muscle loss.

Intake and dosage

Glutamine can be consumed either as an oral powder or as a tablet. It is commercially available in doses of 500 mg. The oral powder can be consumed with a meal or snack and the glutamine tablet should be consumed at least one hour before a meal. It is crucial to follow the recommended dosage guidelines.as taking too much glutamine in supplement form may also result in adverse side effects. 

Approximately 20-30 grams of glutamine intake per day is advised and is proven to be harmless in healthy adult humans. For instance, a clinical study was conducted among athletes where they consumed about 28 grams of glutamine for 14 days. The study concluded that the prescribed amount did not result in any side effects in athletes. The dosage levels change depending on the age and diagnosis, with geriatric cancer patients taking glutamine doses up to  0.65 grams per kilogram of body mass.

In case of a missed dose, try taking the supplement as soon as you remember. Do not take additional medication to make up for a missed dose. An overdose of glutamine is unlikely to result in life-threatening symptoms, but side effects may occur, including nausea, vomiting, joint pain, and hives If any of these side effects occur, seek medical attention right away. 


Even though studies suggest that there are fewer side effects with glutamine intake, it is always important to consult a doctor or a healthcare provider before taking supplements. High doses of glutamine intake must only be consumed if prescribed by a medical professional.

Glutamine in the form of oral powder should always be mixed or taken with food or liquids that are either cold or room temperature. It should not be taken with any hot drinks as glutamine amino acids get destroyed with heat, decreasing glutamine’s viability. It is also recommended to store glutamine supplements in a dry location.

If a person is suffering from kidney or liver disease, it is important to consult their doctor about glutamine supplements. However, usually, it should be avoided as glutamine might react with other medications.

Similarly, clinical studies state that people with psychiatric conditions and seizures should avoid glutamine supplements as they might worsen the conditions.

Usually, glutamine supplementation does not result in symptoms associated with gluten allergy. People who are gluten-sensitive can include glutamine in their diet. However, in some cases, people may be sensitive to glutamine, which may possibly result in side effects.

Side effects

Taking high doses of glutamine might result in severe side effects. As mentioned earlier, people with liver and kidney disease must avoid taking glutamine supplements as they might cause swelling of the liver or brain, and in cases of cancer patients, it is found that certain tumour cells multiply with glutamine intake and can result in severe health conditions that may lead to death. Pregnant women, people with mental disorders and people under certain medications must avoid or consult the doctor before consumption. Glutamine can sometimes trigger an allergic reaction resulting in: muscular and joint pains, nausea, vomiting, and hives. If any of the above signs occur, immediate medical attention and treatment are required.

What other drugs will affect glutamine?

Some of the possible medications that might interact with glutamine include prescribed medicines, vitamins and herbal medications. People need to be cautious when taking glutamine with other medications as it might result in severe conditions. Other possible interactions would be caused with lactulose, where lactulose becomes less effective as there is  increase in ammonia in the body with glutamine intake. In case of colon cancer patients, glutamine supplementation increases the efficacy of the treatment as well as reduces the side effects caused due to the chemotherapy medications (doxorubicin, methotrexate, and 5-fluorouracil). For other cancer treatments, clinical studies suggest that with continuous glutamine intake nerve damage associated with cancer medication is reduced. However, studies [1] suggest that glutamine might stimulate the growth of tumors. More research is needed to determine if glutamine supplementation is safe for cancer patients. But it is always recommended and necessary to consult your doctor before adding supplements to your diet.

Does it work for irritable bowel syndrome?

Irritable bowel syndrome (IBS)affects the person’s digestive system. The most common symptoms are bloating, cramping in the abdomen, constipation and diarrhea. IBS could be caused by glutamine deficiency and with increased glutamine intake there is significant reduction in IBS symptoms. Glutamine protects the inner mucous membrane of the food pipe(esophagus) and the intestinal walls. The mucous membrane acts as a barrier preventing bacterial infection during digestion. Glutamine intake leads to reduction in stress-related IBS  symptoms.


To maintain one’s health, it is important to get adequate proteins that get internally synthesized from amino acids. Glutamine is an important and most abundant amino acid in our body, that acts as the building block of proteins, providing energy to the and helping with intestinal health and liver detoxification. Glutamine is circulated through blood, helping nitrogen transport and ammonia excretion throughout the body. There are two sources of glutamine in the body: it is either internally synthesized or externally consumed. The dietary sources that supplement glutamine externally include vegetables such as cabbage, beetroot, beans,
spinach, parsley, tofu, lentils, and peas, while the meat and dairy sources include beef, chicken, eggs, fish, milk, and cheese. Glutamine boosts intestinal health, improves immunity and promotes immune cell activities, preventing infection and inflammation in the gut. Glutamine is used by athletes due to its immunomodulatory and anti-fatigue role.t is also used by cancer and HIV patients to boost gut health and prevent muscle loss. Glutamine can be consumed either as an oral powder or as a tablet. It is commercially available in measurements of 500 mg. Glutamine overdose can result in life-threatening symptoms. Therefore, it is always recommended to consult the doctor before taking glutamine supplements. It is also critical to seek medical attention right away if you experience any of the side effects. People with mental disorders, liver and kidney disease, cancer patients, and pregnant women must avoid taking glutamine supplements as some of the medications might interact with glutamine and can worsen the condition. IBS could be caused by glutamine deficiency, and with increased glutamine intake, there is a significant reduction in IBS symptoms.It is evident that glutamine supplementation improves the overall immune cell activity, resulting in increased metabolism of our body but remember to always have prescribed doses and follow the necessary precautions.


  1. Cruzat, Vinicius et al. “Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation.” Nutrients vol. 10,11 1564. 23 Oct. 2018, doi:10.3390/nu10111564
  2. Coqueiro, Audrey Yule et al. “Glutamine as an Anti-Fatigue Amino Acid in Sports Nutrition.” Nutrients vol. 11,4 863. 17 Apr. 2019, doi:10.3390/nu11040863
  3. Michael Gleeson. “Dosing and Efficacy of Glutamine Supplementation in Human Exercise and Sport Training”. The Journal of Nutrition, Volume 138, Issue 10, October 2008, Pages 2045S–2049S, doi:10.1093/jn/138.10.2045S
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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Pranitha Ven Murali

Master's degree - Biomedical/Medical Engineering, University of Strathclyde Glasgow, Scotland
Experienced in Medical Writing and Editorial Intern.

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