Glutamine
What is it?
Glutamine is the most abundant free amino acid in plasma and skeletal muscle tissue, representing about 60% of the muscle's free amino acids. It is classified as a conditionally essential amino acid — under normal circumstances the body produces enough, but in states of intense stress (high-intensity training, illness, surgery) demand exceeds endogenous production. It plays a central role in intestinal health, immunity and acid-base balance.
Main Benefits
- Support for intestinal mucosal integrity
- Immune support during intense training phases
- May attenuate immune decline after prolonged exercise
- Muscle acid-base balance
- May reduce intestinal permeability under stress
Who it's for
- •High-intensity athletes with frequent training
- •People with leaky gut syndrome or dysbiosis
- •Individuals in periods of high physical stress
- •Those recovering from injuries or surgeries
- •People on very restrictive diets with immune risk
Common Dose
5g to 10g per day, split into 1 to 2 doses. Can be consumed post-workout and before bed. In clinical contexts (intestinal), it may be used at higher doses under guidance.
How to Choose
Glutamine is most indicated when there is intestinal compromise, low immunity or very high physical stress. For recreational athletes with adequate protein intake, the benefits for muscle synthesis are marginal — dietary protein already provides enough glutamine. The greatest differential of supplementation is in intestinal and immune support, not muscle anabolism. If the goal is exclusively muscle gain, prioritize total protein and Leucine.
What the Science Says
The evidence for glutamine in muscle protein synthesis in healthy individuals with adequate protein intake is weak. The strongest studies are in the clinical context — intestinal health, immunity and recovery from intense catabolic states. In athletes, supplementation showed mixed results for muscle recovery, with more consistent benefits for immunity in high-volume endurance sports. Glutamine is the primary fuel for enterocytes (intestinal cells) and immune cells.
Possible Side Effects
Generally very well tolerated. At high doses it may cause mild gastrointestinal discomfort. People with kidney or liver disease should consult a doctor before supplementing.
Final Summary
Glutamine is a valuable supplement mainly for intestinal health and immunity — not for direct hypertrophy. For athletes with adequate protein intake, the benefit for muscle synthesis is marginal. More relevant in contexts of high physical stress, restrictive diets or intestinal compromise. Use with a clear purpose and not as a protein substitute.