What is glutamine?
Glutamine is a conditionally essential amino acid — the body can synthesise it, but demand can exceed production under conditions of physical stress, illness, or injury. It plays roles in immune function, gut barrier integrity, and nitrogen transport between tissues. It is abundant in dietary protein sources, particularly meat, fish, dairy, and eggs.
How it works
Glutamine is a primary fuel source for rapidly dividing cells including immune cells and intestinal epithelial cells. During intense exercise, plasma glutamine levels decline, which may temporarily compromise immune function. Supplementation aims to restore these levels and support recovery.
What the research says
- No significant benefit for muscle hypertrophy or strength in healthy individuals with adequate protein intake (Antonio & Street, 1999)
- May reduce upper respiratory tract infection incidence in endurance athletes during heavy training blocks
- Clinically beneficial in critical care settings and post-surgical recovery — not equivalent to athletic supplementation
- Gut health benefits are better supported in clinical populations than healthy athletes
Effective dose
5–10g post-workout if using. For most people eating 1.6g+ of protein per kg bodyweight daily, dietary glutamine intake is sufficient and supplementation provides no meaningful additional benefit. More relevant for endurance athletes in heavy training blocks or individuals with restricted diets.
What to check on the label
Glutamine is frequently added to protein powders and recovery products as a marketing addition. Its presence on a label is not a quality indicator. Assess the product on its overall protein content and amino acid profile rather than glutamine inclusion.
Safety
Safe at recommended doses. No established adverse effects in healthy adults at 5–10g per day. Higher doses have been used in clinical settings without significant adverse events.