What is glutamine?

From the Guidelines

Glutamine is a conditionally essential amino acid that plays a critical role in health, particularly in times of illness or stress, and its supplementation has been shown to be beneficial in certain clinical settings, such as in critically ill patients, at doses of 0.2-0.4 g/kg/day, as recommended by the ESPEN guidelines 1.

Key Points About Glutamine

• Glutamine is the most abundant free amino acid in the bloodstream and muscles, serving as a fuel source for cells in the immune system and intestines.
• It is considered conditionally essential, meaning the body can produce enough for normal functions, but may require additional glutamine during illness, injury, or stress.
• Glutamine helps maintain intestinal lining integrity, supports immune function, aids in wound healing, and contributes to muscle recovery after exercise.
• Food sources rich in glutamine include animal proteins and plant sources like beans, cabbage, and spinach.
• Supplemental glutamine is used in clinical settings, typically at doses ranging from 5 to 30 grams daily, depending on the condition being treated.

Clinical Use of Glutamine

• The ESPEN guidelines recommend glutamine supplementation in critically ill patients, at doses of 0.2-0.4 g/kg/day, to reduce mortality and improve morbidity 1.
• However, a more recent study suggests that high-dose parenteral glutamine should not be administered in critically ill patients with acute or chronic kidney disease, due to potential harm 1.
• The optimal dose and clinical use of glutamine supplementation should be determined on a case-by-case basis, considering the individual patient's condition and needs.

Important Considerations

• Glutamine supplementation should be used under medical supervision, particularly in clinical settings.
• The benefits and risks of glutamine supplementation should be carefully weighed, considering the individual patient's condition and the latest available evidence.
• Further research is needed to fully understand the effects of glutamine supplementation in different clinical contexts.

From the Research

Definition and Role of Glutamine

• Glutamine is the most abundant amino acid in the human body, performing multiple roles in human physiology 2, 3, 4, 5, 6.
• It is a conditionally essential amino acid, meaning that under normal conditions, the body can synthesize enough glutamine to meet its needs, but during times of stress, such as illness or injury, the body may require additional glutamine from the diet 2, 3, 4, 5, 6.

Physiological Functions of Glutamine

• Glutamine is an important metabolic substrate for cells, particularly for immune cells, and is involved in the synthesis of proteins, nucleotides, and other biologically important molecules 3, 4, 6.
• It plays a crucial role in the regulation of gene expression, protein turnover, anti-oxidative function, nutrient metabolism, immunity, and acid-base balance 5.
• Glutamine is also involved in the maintenance of intestinal function and barrier integrity, and its depletion can lead to increased intestinal permeability and translocation of bacteria 4.

Clinical Importance of Glutamine

• Glutamine supplementation has been shown to be beneficial in improving nitrogen balance, reducing morbidity and mortality, and enhancing immune function in critically ill and injured patients 2, 3, 4, 5.
• It may also have a role in the prevention and treatment of diseases such as sepsis, cancer, and HIV/AIDS, where glutamine depletion is common 3, 4, 5.
• However, the optimal dosage and timing of glutamine supplementation, as well as its effects on different patient populations, require further research 3.