L-glutamine
L-glutamine
Supplements. Modern nutrition.
Also called Glutamine, Gln, Glutamine powder
Pinyin: gǔ ān xiān àn
Spanish: L-glutamina
Liver and kidney cautionThe most common free amino acid in the body, used by muscle, gut and immune cells, and sold mainly for gut and muscle support.
Did you know? Glutamine is the most abundant free amino acid in the human body, and most of it is stored in skeletal muscle.
What it may help, and how strong the proof is
- Anemia & blood building. In sickle cell disease, a prescription L-glutamine powder (Endari) reduced painful crises compared with placebo in a large trial of about 230 people. The FDA approved it in 2017 for people age 5 and up. This is a doctor-supervised medical use, not a home remedy.See the research: 16 studies in peoplePromising proof
- Digestion & gut health. Glutamine is studied for mouth and gut soreness caused by chemotherapy (mucositis). Reviews disagree: some find fewer severe sores, while others find no clear effect. Evidence that it heals a healthy gut lining is weak.See the research: 42 studies in peoplePromising proof
- Muscles & exercise. Glutamine is sold for muscle recovery. Many trials in healthy athletes did not show faster recovery or better performance.See the research: 20 studies in peopleUnproven
Parts of the body
Traditional use
Glutamine has no long folk history. Interest grew from hospital research on critically ill and recovering patients, and in 2017 the FDA approved a prescription L-glutamine powder for sickle cell disease.
How it is classified
How people take it
Studies have used a wide range of doses, often several grams a day, and no standard dose has been set for sports or gut use. Prescription L-glutamine powder for sickle cell disease is dosed by body weight under a doctor's care. The powder can be stirred into cold or room-temperature drinks or soft food.
Powder, capsule and food.
Where to get it
The body makes glutamine, and food adds more. Good sources are meat, fish, eggs, dairy, beans, spinach and cabbage. Powders and capsules are sold in health stores and online, and the prescription powder is sold at pharmacies.
Be careful
Common side effects are constipation, nausea, headache, stomach pain, cough, chest pain, and aches in the back or limbs. Ammonia from glutamine can build up in people with liver or kidney disease, so they should only use it with a doctor's approval. Some cancer cells use glutamine as fuel, so people with cancer should only take it with their care team, and safety in pregnancy and breastfeeding is not well studied.
Avoid if: liver disease; kidney disease; cancer (ask the care team first); pregnancy (not well studied).
Mixing with other things
- Works well together
Both are sold for gut lining support. Evidence for the pair is limited.
The honest take
Glutamine is a normal amino acid, and the FDA approved a prescription powder for sickle cell disease. Sports and gut claims for store products are ahead of the research. People with liver, kidney or cancer conditions should check with a doctor first.
Sources
Each “See the research” link opens PubMed, the U.S. National Library of Medicine's index of medical studies, showing only trials and reviews done in people. The number tells you how much a use has been tested, not whether it worked. The proof rating tells you that.
Study counts checked October 2026.