Glutamine is the most abundant amino acid (protein building block) in the blood.
It's an important energy source for cells that multiply quickly, like those of the gastrointestinal (GI) tract and immune system.
It is also a source of nitrogen for many reactions in the body.
Glutamine is also found in foods and sold over-the-counter (OTC) as a dietary supplement, which may also be called L-glutamine.
This article focuses on glutamine's uses as a dietary supplement, glutamine nutrition, and safety tips to consider before adding it to your daily regimen.
Glutamine Supplement Facts
- Active ingredient: Glutamine
- Alternate names: L-glutamine, levoglutamide, glutamic acid amide
- Legal status: Over-the-counter (OTC) dietary supplement (United States); available as the FDA-approved prescription products Endari for sickle cell disease and Nutrestore for short bowel syndrome
- Suggested dose: 20 to 35 grams (g) daily
- Safety considerations: Not recommended during pregnancy, breastfeeding, or in healthy children due to a lack of safety data; may interact with prescription diabetes medications
What Are Glutamine's Uses?
Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian (RD) or registered dietitian nutritionist (RDN), pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.
Besides its research and approval for sickle cell disease and short bowel syndrome, glutamine has been studied for several other uses, including athletic performance and burn healing.
As with most dietary supplements, the evidence is mixed.
Here's the latest research about glutamine's effects.
:max_bytes(150000):strip_icc()/GettyImages-1282873456-a37aadf3943144bd99d82b9746bbe077.jpg "The Health Benefits of Glutamine (1)")
Wound Healing
When the body is under stress (due to serious injuries, burns, or infections), it may need more glutamine than it can produce.
Glutamine supplementation plays a role in several aspects of wound healing, according to a review of 39 clinical trials.
Trials showed supplementing with glutamine can shorten the length of hospital stays. It may also decrease markers of inflammation, like interleukin-6 (IL-6) and C-reactive protein (CRP).
Another review showed that glutamine supplementation was associated with faster healing in burn patients.
Gut Health
Glutamine plays several roles in the GI tract. For instance, it protects the mucosal barrier of the intestines and can prevent toxins from reaching the bloodstream.
Glutamine has been researched for various digestive diseases. However, there's little evidence it's beneficial.
One possible exception is severe acute pancreatitis (sudden pancreas inflammation). One review determined that giving glutamine in addition to nutrition via a feeding tube lowered risks of the following:
- Multiple organ dysfunction syndrome (MODS)
- Length of hospital stay
- Death
According to a review, glutamine only slightly improved the following in people with inflammatory bowel disease (IBD):
- Inflammation
- Intestinal symptoms
- Disease course
This was true across delivery methods—including orally (by mouth), intravenously (through an IV), or enterally (through a feeding tube)—for people in hospital and outpatient settings. However, the researchers suggested it was unclear whether the benefits were from glutamine alone.
It's also been studied in infants with severe GI diseases, such as the following:
- Acute necrotizing enterocolitis (NEC)
- Intestinal perforation
Theoretically, glutamine can help repair injured tissue. However, it did not affect the survival or infection rates of the infants.
Oral Mucositis
Oral mucositis (swelling and mouth ulcers) is a common complication of cancer treatments.
People with head and neck cancer treated with radiation plus glutamine had less severe mouth sores than those who didn't receive glutamine, even though the likelihood of developing mucositis was the same. People who took glutamine also had lower rates of opioid pain medications and tube feeding.
Similar results were seen when glutamine supplementation was studied for people with cancer treated with either chemotherapy or radiation. Glutamine didn't reduce the incidence of oral mucositis but decreased its severity.
However, not all data are promising. For instance, a study in pediatric cancer patients showed that glutamine supplementation did not lower the likelihood or severity of mouth sores.
A review concluded that there wasn't enough evidence to recommend glutamine for preventing or treating oral mucositis.
Critical Illness
Because glutamine levels may be depleted in cases of severe illness, several studies have examined its effects on people hospitalized with these conditions.
Glutamine is typically given intravenously or enterally within a hospital setting.
The results are mixed, but there appears to be only limited benefit overall. Studies have shown that only about 1 in 3 patients admitted to the intensive care unit (ICU) have low glutamine levels.
Glutamine supplementation shouldn't routinely be started for critically ill patients except those with severe burns.
May Improve Athletic Performance
Some people take glutamine to enhance exercise performance, but little evidence supports this claim.
In a review of 25 clinical trials, glutamine did not affect athletic performance, body composition, or the immune system.
Of note, it may help with weight loss, according to the review.
Prescription Glutamine
Glutamine is available as two prescription medicines that have been approved by the Food and Drug Administration (FDA):
- Endari for people with sickle cell disease
- Nutrestore for people with short bowel syndrome
They are both glutamine powders that require a prescription from a healthcare provider.
Nutrition
Most adults consume between 3 and 6 g of glutamine daily from foods containing protein.
Here are the amounts of glutamine found in a 3.5-ounce serving of these common foods:
- Beef: 1.2 g
- Tofu: 0.6 g
- Egg: 0.6 g
- Corn: 0.4 g
- Skim milk: 0.3 g
- White rice: 0.3 g
Glutamine is also available as an OTC supplement in tablet, capsule, liquid, and powder forms. It's also an ingredient in some protein supplements.
What Are the Risks of Taking Glutamine?
Side effects that were seen in trials of the prescription product Endari (L-glutamine powder) included:
- Constipation
- Nausea
- Headache
- Stomach pain
- Cough
- Back pain
- Chest pain
These side effects were seen in up to 20% of people with sickle cell disease who used prescription glutamine.
There isn't much data on side effects from OTC glutamine supplements, though they are likely similar to those listed above.
Take glutamine at the recommended dose for best results, and contact your healthcare provider or pharmacist if you experience side effects.
Do keep the following precautions in mind when using glutamine:
- Severe allergic reaction: Avoid using glutamine products if you have a known allergy to it or its ingredients. Ask your pharmacist or healthcare provider for a complete list of the ingredients if you're unsure, mainly if you're using a combination workout supplement.
- Pregnancy: Glutamine supplements are not recommended due to insufficient safety data. Normal amounts of glutamine consumed in a typical diet shouldn't be problematic. For more information, consult with your healthcare provider.
- Breastfeeding: Glutamine supplements are not recommended while breastfeeding due to insufficient safety data.
- Children: Glutamine has been studied in seriously ill children and infants. However, there is very little known safety data, so it is not recommended unless used under a healthcare provider's supervision.
- Other modifications: Because the kidneys break down glutamine, it's not recommended for people with kidney disorders. People with liver failure may also have high glutamine levels and shouldn't take additional supplements.
Interactions
Glutamine may interact with the following medications:
- Insulin and other diabetes medications: Glutamine has changed blood sugar levels and can change the amount of medicine needed for some people with diabetes.
- Dietary supplement arginine: Levels of this amino acid have increased from glutamine use.
It is essential to carefully read a supplement's ingredients list and nutrition facts panel to know which ingredients and how much of each ingredient is included. Please review the supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications.
Dosage
Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs.
While there is no recommended dosage for oral glutamine supplements, studies have used the following glutamine doses:
- 21–30 grams for inflammatory bowel disease
- Up to 45 grams a day for six weeks for strength training
The FDA has approved the following recommended doses for prescription medications that contain glutamine:
- Endari: 5–15 grams twice a day, mixed in 8 ounces of liquid or 4–6 ounces of food, for sickle cell complications
- Nutrestore: 5 grams taken six times a day, mixed in 8 ounces of water, for short bowel syndrome
Adult glutamine doses of up to about 30 grams a day seem to be well-tolerated.
Dietary supplements are not regulated like drugs in the United States. They can cause interactions with medications or have other safety concerns. For this reason, it’s important to be aware of what to look for when choosing a supplement, such as third-party testing, potential drug interactions, and more.
Summary
Glutamine is an amino acid made in the body. Most healthy people consume all they need through protein-containing foods, such as beef, tofu, and eggs.
But sometimes, supplementation is warranted, typically under the supervision of a healthcare provider. Some examples of people who might benefit from glutamine are those with severe burns or those undergoing cancer treatment.
The FDA has approved prescription products Endari and Nutrestore following rigorous studies. However, the agency has not approved OTC glutamine supplements.
If you decide to try glutamine, purchase a product that has been third-party tested by USP, ConsumerLab, or NSF if possible.
Certification for a company does not mean the product is safe or effective. Instead, it offers assurance that the ingredients match what is listed on the label and that the product is free of contaminants.
Frequently Asked Questions
What is glutamine?
Glutamine is an amino acid that's made in the body and also found in some protein-containing foods. It's available as an OTC dietary supplement and two FDA-approved prescription medications.
What does glutamine do?
Glutamine is an energy source for cells that rapidly divide, like those of the GI tract and immune system. It also supplies nitrogen needed in many reactions in the body.
What is glutamine good for?
Though the evidence is still limited, glutamine may promote wound healing for people with severe burns. It may also improve outcomes of people with acute pancreatitis, or cancer patients with mouth sores.
Are there different routes of administering glutamine?
Yes. Glutamine can be given intravenously (IV), enterally (through a feeding tube), or orally (by mouth). OTC dietary supplements are available as powders, capsules, and tablets and are often labeled as L-glutamine.
Does glutamine enhance athletic performance?
There's not enough evidence to recommend glutamine for this use.
