Glutamine

How strong is the research?

1 paper read, 1 supporting.

Who was studied: Patients with intestinal injury or disease, not healthy adults with an unpredictable gut.

How much to take

daily

5–10 g

Often combined with probiotics for synergistic gut health benefits. Effects may appear within 2-4 weeks.

Before you take it

• No NIH/IOM Tolerable Upper Intake Level established for supplemental L-glutamine.
• Contraindicated in decompensated hepatic cirrhosis and hepatic encephalopathy: oral doses of 10–20 g have been documented to elevate serum ammonia and worsen psychometric measures of hepatic encephalopathy in patients with advanced liver disease (glutamine is catabolized to glutamate and ammonia, which overwhelm impaired hepatic clearance).
• Caution in severe renal impairment: glutamine catabolism adds nitrogen load that impaired kidneys cannot clear efficiently.
• Caution in seizure disorders: glutamine is a direct biosynthetic precursor to glutamate, the principal excitatory neurotransmitter; theoretical risk of lowering seizure threshold.
• Theoretical concern in active cancer: glutamine is a primary fuel for rapidly dividing cells; clinical significance of oral supplemental doses is debated and unresolved.
• High-dose IV glutamine (>0.35 g/kg/day) was associated with increased mortality in multi-organ failure in the RedOXS and MetaPlus trials; this signal applies to parenteral high-dose use in critical illness, not to oral supplementation at 5–15 g/day.
• Insufficient safety data in pregnancy and lactation for supplemental doses.
• Generally well-tolerated in healthy adults at oral doses up to 40 g/day in short-term trials; FDA approved L-glutamine (Endari) at 5 g three times daily for sickle cell disease.

What we make of it

The source is an invited expert summary, not a trial.