How it works
Glutamine is a conditionally essential amino acid. It fuels immune cells and cells lining the gut and plays a role in nitrogen transport. Blood glutamine can fall after very prolonged or exhausting exercise, which led to the idea that supplements might support immunity and recovery. However, the body makes plenty of glutamine, a normal diet supplies roughly 3–6 g per day, and adding more has not reliably changed muscle or performance outcomes in healthy, well-fed athletes. Medical uses of glutamine in critical illness are a separate topic.
What research supports
- Little evidence of benefit for muscle mass, strength or performance in healthy people
- Some studies suggest it may help maintain gut barrier function during intense exercise in heat
- Evidence for preventing infections in athletes is inconsistent
Dosage
Research doses vary widely, commonly 5–10 g per day, and some gut studies have used about 0.25–0.9 g/kg before exercise. Benefits are uncertain at any dose.
Timing
Studies have used glutamine after training, before bed, or before exercise in heat. No timing strategy has been shown to produce clear performance benefits.
Side effects
- Generally well tolerated
- Bloating or digestive discomfort at high doses
Cautions
- People with liver disease, kidney disease, bipolar disorder or seizure disorders should consult a doctor before use
- Not a substitute for adequate total protein and energy intake
- Athletes subject to anti-doping rules should only use products certified by an independent third-party testing program for banned substances; certification lowers, but does not eliminate, the risk of contamination.
Food sources
Meat and fish, Eggs, Dairy products, Tofu, Beans and lentils, Cabbage and spinach.