L-Glutamine 500 mg by Thorne

If “L-glutamine for gut health” is what brought you here, you’re the right audience. This fits endurance athletes in heavy blocks who catch colds after races, people with occasional gut upset after antibiotics or travel, and those recovering from minor injuries or surgery who want nutritional support for tissue repair. It’s a maintenance-level dose for keeping up with training or stressful periods. For established gut disorders or significant weight loss from illness, higher powder doses are typically used with clinician guidance.

L-glutamine is an amino acid that your gut lining cells prefer as fuel. By feeding these cells, it helps maintain tight junctions (the seals between intestinal cells) and supports barrier integrity. Immune cells also use glutamine during stress, which is why athletes sometimes see fewer post-event infections. In the liver it carries nitrogen safely, helping manage ammonia (a waste product from protein breakdown). Evidence for muscle building is weak; its effects are mainly gut integrity and recovery from physiological stress.

The suggested use is one capsule three times daily, with or without food. For gut goals, many take glutamine between meals or at bedtime so it isn’t competing with other amino acids from protein-heavy meals. Expect gut-comfort changes within 2 to 4 weeks if it’s going to help; post-exercise immune effects are seen around heavy training blocks. This capsule total (about 1.5 grams per day) is upkeep. Clinical repletion protocols often use 5–15 grams per day as powder, short term.

Skip L-glutamine if you have hepatic encephalopathy (a liver-related condition where ammonia builds up) or severe kidney disease unless your clinician agrees. If you’re in active cancer treatment, coordinate with your oncology team; glutamine is sometimes used for mouth sores after chemotherapy, but dosing and timing matter. If you have celiac disease, inflammatory bowel disease, or chronic diarrhea, don’t self-treat—work with a clinician and track objective markers like hs-CRP (a general inflammation marker) alongside symptoms.