Glutamine: A misunderstood amino acid with therapeutic potential

Area of Science:

• Nutrition Science
• Gastroenterology
• Metabolic Research

Background:

• Glutamine, a conditionally essential amino acid, is crucial for enterocyte proliferation and intestinal barrier integrity.
• Depleted plasma glutamine levels, seen in critical illness or malnutrition, lead to intestinal atrophy and increased permeability.
• Intravenous glutamine is established in critical care to prevent intestinal atrophy.

Purpose of the Study:

• To quantify dietary and endogenous glutamine contributions.
• To determine optimal oral glutamine supplementation dosages for intestinal health.

Main Methods:

• Comparative assessment of dietary amino acid intake versus endogenous glutamine production.
• Review of glutamine supplementation pharmacokinetics.
• Analysis of clinical study outcomes based on different glutamine dosages.

Main Results:

• Endogenous production accounts for approximately 88% of daily glutamine metabolism, with muscle protein breakdown being a major source.
• Oral glutamine supplementation at doses mirroring enterocyte daily metabolism (30g) showed positive outcomes for intestinal permeability.
• Supplementation based on dietary intake levels did not yield significant benefits.

Conclusions:

• Clinical oral glutamine doses for intestinal disorders should align with the small intestine's daily metabolic needs, not just dietary intake.
• Higher doses (e.g., 30g) are more effective in supporting intestinal barrier function and preventing atrophy.