L-Glutamine

Supplements · Sports Performance · Supplement, Typed Supps

Your body already makes plenty of this — extra rarely helps healthy gym-goers.

Stage by stage

Intake (Powder): Absorbed efficiently in the small intestine.
Small intestine (Direct fuel for gut cells): Also used directly as fuel by intestinal cells during absorption.
Bloodstream (Carried to muscle & immune cells): Carried in the blood to muscle and immune cells.
Gut lining & recovery (Studied roles): Studied for roles in gut lining maintenance and recovery from intense exercise or illness.

What the evidence supports

Improving muscle recovery or reducing soreness in healthy trained people — insufficient evidence. Pooled trial data, including large reviews, show no meaningful effect on creatine kinase or performance in non-deficient people.
Reducing infections and length of hospital stay in critically ill or post-surgical patients — moderate evidence. This is where the clinical evidence sits — supervised, catabolic patients whose plasma glutamine has dropped — not the general population.
Repairing the gut or 'leaky gut' in otherwise healthy people — limited evidence. Most data are on permeability markers or clinical settings; trials with hard clinical endpoints in healthy people are lacking.
Boosting immunity in athletes — insufficient evidence. Trials do not support a meaningful immune benefit in trained people.

Typical dose

About 5 g/day for general use (clinical protocols use 20–30 g/day)

Upper limit: No formal UL; intakes around 14 g/day are well tolerated in healthy adults

Timing

With food, standard dosing.

Time to effect

Weeks: Any reported gut or recovery-related effect in studies.

Common myth

“Everyone needs to supplement glutamine.” In reality: Your body produces substantial amounts on its own — supplementation matters most during genuine physiological stress, not everyday use.