L-Glutamine

Clear benefit in clinical settings (burns, critical illness, gut-barrier dysfunction). Benefits for healthy exercisers are much less convincing.

A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.

Strong evidence in clinical populations for reducing infections and supporting gut-barrier integrity. In healthy athletes, meta-analyses show minimal effects on performance or muscle recovery. Plasma glutamine does drop during prolonged exercise, but supplementation has not consistently improved outcomes.

• Supports gut-barrier integrity in clinical populations
• Fuel source for immune cells during physiological stress
• May reduce infection rates in critical illness

Clinical: 20–30 g/day in divided doses. Sports: 5–10 g/day, though evidence for benefit in healthy athletes is weak.

• Generally well tolerated
• High doses may cause GI discomfort

Generally safe at typical doses. Caution in liver disease (ammonia metabolism). Avoid in renal insufficiency at high doses.

The gap between clinical and sports-nutrition evidence is large. Healthy individuals synthesize adequate glutamine under normal conditions.

• Immunity50
• Recovery40