L-glutamine supplement: gut health, muscles and what to know
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- L-glutamine powder. Best for: Adults whose doctor has suggested glutamine. See options on Amazon
- L-glutamine 500 mg capsules. Best for: People who want smaller doses. See options on Amazon
- Glutamine gut support blends. Best for: Buyers comparing gut health formulas. See options on Amazon
What glutamine is
MSK's About Herbs database describes glutamine as an amino acid absorbed from food and made and stored in the body, mainly in muscles and lungs. It is a protein building block and a major fuel for cells, and it is essential for keeping the intestinal lining healthy.
Glutamine also helps make glutathione with cysteine and glycine, and helps remove excess ammonia. Although it is abundant, people recovering from surgery, sepsis or intense exercise, and those with cancer or AIDS-related wasting, may need more. Hospitals use intravenous glutamine, and oral medical food products exist.
What the research shows
| Use | What MSK reports |
|---|---|
| Muscle mass and strength | Evidence lacking |
| Irritable bowel syndrome | Reduced symptoms in one study |
| Surgery and critical illness | May help nitrogen balance and gut integrity; outcome data mixed |
| Sickle cell anemia | Fewer pain crises |
| Cancer treatment side effects | May help neuropathy, mouth sores and some diarrhea |
Muscle. Although it is marketed for muscle building, MSK says evidence is lacking for glutamine increasing muscle mass and strength.
Gut. In people with irritable bowel syndrome, supplementation reduced related symptoms. Glutamine's role in maintaining the intestinal lining is why it is marketed for gut health, but broad gut health claims go beyond the evidence.
Hospital settings. In surgical or critically ill patients, glutamine may improve nitrogen balance, protect the gut lining and shorten hospital stays, but results on preventing infections and improving outcomes are mixed. It did not shorten hospital stays in severe burns.
Glutamine in cancer care
Much of the glutamine research comes from cancer settings, where it is used under medical supervision. MSK reports that studies suggest glutamine may help against nerve damage, mouth sores and certain chemotherapy-related diarrhea, and that intravenous glutamine reduced nausea, vomiting and diarrhea in some gastric and colorectal cancer patients. Glutamine alone reduced postoperative complications and hospital stays in colorectal cancer surgery. Other studies suggest it may reduce radiation-related problems, though results for radiation skin damage conflict and cachexia trials are mixed.
Because tumor cells can also use glutamine to grow, these decisions belong with an oncology team, not self-treatment.
Safety
- Generally tolerated. Studies in cancer patients suggest oral glutamine is well tolerated, though some specific preparations caused swelling, digestive symptoms, headache, fever and infections.
- Liver. A 35-year-old athlete developed severe abdominal pain and yellowing of the eyes after three weeks of glutamine powder, with tests suggesting liver injury; she recovered after stopping. NOW Foods' label flags liver disease.
- Kidneys. Acute kidney injury was reported after long-term high-dose use (18 g).
- Bipolar disorder. NOW Foods advises consulting a physician if you have bipolar disorder.
- Lactulose. Glutamine may reduce lactulose's ammonia-lowering effect (not its laxative use).
- Cancer. Tumor cells can depend on glutamine for growth, so people with cancer should only use it with their oncology team.
Doses and forms
- Powder. NOW Foods' L-Glutamine Powder gives 5 g (5,000 mg) per rounded teaspoon, mixed in juice between meals, 1 to 2 times daily as needed.
- Capsules. L-glutamine is also sold in 500 mg capsules, a much smaller amount per unit than a powder scoop.
- Free-form. NOW Foods describes its powder as pure, free-form L-glutamine with no other ingredients.
- Food first. Wheat, corn, barley, peanuts, soybeans, egg whites and milk supply glutamine.
How to choose an L-glutamine supplement
- Know your goal. For muscle building, evidence is lacking; for gut symptoms, talk with a doctor about the cause first.
- Single ingredient. Free-form L-glutamine with no additives keeps it simple.
- Stay at label doses. Kidney injury was reported with long-term high doses.
- Check medical conditions. Liver disease, kidney disease, bipolar disorder and cancer all call for a doctor's input.
- Storage. NOW Foods advises a cool, dry, dark place after opening.
What to look for when you buy
L-glutamine powder
Best for: Adults whose doctor has suggested glutamine
NOW Foods' powder gives 5 g free-form L-glutamine per rounded teaspoon with no other ingredients.
Watch out: Not proven for muscle growth. Ask your doctor if you have liver or kidney disease, bipolar disorder or cancer.
See options on AmazonL-glutamine 500 mg capsules
Best for: People who want smaller doses
500 mg capsules give a smaller, measured amount.
Watch out: Same medical cautions. Check total daily intake.
See options on AmazonGlutamine gut support blends
Best for: Buyers comparing gut health formulas
Some gut formulas combine glutamine with other ingredients.
Watch out: Blends were not what glutamine studies tested. See a doctor for ongoing gut symptoms.
See options on AmazonQuestions people ask
- What is L-glutamine good for?
- It may help some medical situations, such as recovery after surgery and IBS symptoms in one study. Evidence does not support it for building muscle.
- Is L-glutamine good for gut health?
- Glutamine helps maintain the intestinal lining, and one IBS study found fewer symptoms, but broader gut claims are not well proven.
- How much L-glutamine should I take?
- Follow the label. NOW Foods' powder is 5 g per serving, 1 to 2 times daily as needed.
- Is L-glutamine safe?
- Usually well tolerated, but case reports describe liver injury and kidney injury with long-term high doses.
- Does L-glutamine build muscle?
- MSK says evidence is lacking for increasing muscle mass and strength.
Sources
- Glutamine (mskcc.org), Memorial Sloan Kettering Cancer Center, About Herbs
- L-Glutamine Powder (www.nowfoods.com/products/sports-nutrition/l-glutamine-powder), NOW Foods