L-Glutamine Dosage Calculator
The most abundant amino acid in the body. Becomes conditionally essential under high training loads, supporting gut barrier integrity, immune function, and glycogen resynthesis during heavy exercise blocks.
What is L-Glutamine?
L-glutamine is the most abundant free amino acid in plasma and muscle (60% of the free amino acid pool), serving as the primary fuel for rapidly dividing cells including enterocytes (intestinal lining), lymphocytes, and macrophages. It is classified as conditionally essential — adequate under normal conditions but insufficient during physiological stress (intense training, surgery, infection). During heavy exercise, plasma glutamine drops by 20–40% as muscle glutamine is mobilised for gluconeogenesis, immune function, and gut fuel. This glutamine depletion is implicated in the immunosuppression observed in overtrained athletes (the "open window" hypothesis), increased intestinal permeability ("leaky gut") during intense training, and delayed glycogen resynthesis. Research by Antonio & Street (1999, Journal of Strength and Conditioning Research) and Gleeson (2008) established the immune and gut-protective roles of glutamine in heavily training athletes. Oral glutamine supplementation (0.1–0.3 g/kg/day) mitigates post-exercise glutamine depletion, reduces infection incidence in endurance athletes, and supports intestinal barrier function.
How to Take L-Glutamine
**Post-workout recovery:** 0.1–0.2 g/kg body weight immediately after training (7–14 g for most athletes), mixed in water or a recovery shake alongside protein and carbohydrates. **High training volume / overtraining prevention:** 0.1–0.3 g/kg/day in 2 divided doses (post-workout + bedtime). **Gut health / intestinal permeability:** 5–10 g/day in the morning on an empty stomach for direct delivery to enterocytes. Glutamine powder dissolves readily in water and is flavourless — easy to add to any beverage.
Timing Recommendations
**Post-workout is the primary evidence-supported window** — glutamine replenishes the intramuscular pool depleted by exercise and supports the post-exercise immune dip. A second dose at bedtime complements overnight muscle repair and maintains plasma glutamine levels during the extended overnight fast. For gut health without specific athletic goals, morning dosing on an empty stomach maximises small intestinal delivery before competition from dietary amino acids.
Potential Side Effects & Safety
Glutamine is extremely safe at doses up to 40 g/day in clinical trials (used in ICU nutrition). GI bloating at doses > 15 g/day on an empty stomach; take with liquid. High-dose glutamine raises plasma glutamate — a theoretical concern for individuals with glutamate sensitivity (MSG sensitivity) or excitotoxicity-related conditions (ALS, epilepsy). No clinically significant drug interactions at standard doses.
Who should avoid L-Glutamine?
ALS (amyotrophic lateral sclerosis): glutamine is metabolised to glutamate, an excitatory neurotransmitter — potentially harmful in motor neuron disease. Renal insufficiency: glutamine metabolism generates ammonia (via glutaminase); impaired ammonia clearance in CKD may worsen uraemia. Hepatic encephalopathy: same ammonia concern in severe liver disease. Epilepsy: glutamate excess may lower seizure threshold.
Best Stacks with L-Glutamine
Glutamine + whey protein post-workout maximises both gut integrity (glutamine) and muscle protein synthesis (leucine/EAAs). Glutamine + glycine + zinc for comprehensive gut barrier repair (the 3-component leaky gut protocol). For immunity: glutamine + vitamin C + zinc covers three independently validated immune-support mechanisms during heavy training blocks.
Scientific References
All dosage recommendations are grounded in peer-reviewed research.
- 1Glutamine supplementation and its effects on the immune system and gut function in endurance athletes
Exercise Immunology Review · 2008
- 2L-Glutamine supplementation: effects on recovery from eccentric exercise
Journal of the International Society of Sports Nutrition · 2015
L-Glutamine Dosage Calculator
Personalized to your body weight
Enter your weight above to see your personalized dosage
Safety notes
- ALS and epilepsy: glutamine converts to glutamate — consult a neurologist before supplementing.
- Renal insufficiency / hepatic encephalopathy: ammonia clearance is impaired — medical supervision required.
- Bloating at > 15 g on empty stomach — take with water or add to a shake.
- Safe up to 40 g/day in clinical settings — standard athletic doses (5–20 g) have an excellent safety record.
This calculator provides general guidance only. Always consult a qualified healthcare professional before starting any supplement.