From the Guidelines
Glutamine is a non-essential amino acid that serves multiple important functions in the body, and the correct answers are (a), (b), and (d).
Key Points
- Glutamine is commonly supplied in total parenteral nutrition formulations to support patients who cannot receive adequate nutrition through the gastrointestinal tract 1.
- It increases intestinal cellularity by serving as a primary energy source for rapidly dividing cells like enterocytes in the intestinal mucosa, helping maintain gut barrier function and mucosal integrity 1.
- Glutamine is also a substrate for gluconeogenesis, particularly in situations of metabolic stress, where it can be converted to glucose in the liver and kidneys 1.
- However, glutamine is not an essential amino acid (option c is incorrect) because the body can synthesize it from other amino acids, primarily in skeletal muscle 1.
- During catabolic states like critical illness, trauma, or surgery, glutamine may become conditionally essential as the body's demand exceeds its production capacity 1.
Recommendation
The use of glutamine supplementation in total parenteral nutrition is recommended, particularly in critically ill patients, as it has been shown to have beneficial effects on morbidity and mortality outcomes 1. However, the optimal dose and duration of glutamine supplementation are still unclear and require further study 1.
Evidence
The most recent and highest quality study on this topic is the 2020 ESPEN guideline on perioperative nutrition, which recommends the use of glutamine supplementation in surgical patients 1. Another recent study published in 2017 also supports the use of glutamine supplementation in surgical patients 1. Overall, the evidence suggests that glutamine supplementation can be beneficial in certain patient populations, but further research is needed to fully understand its effects and optimal use.
From the Research
Glutamine Properties and Functions
- Glutamine is supplied in total parenteral nutrition, as it is considered a conditionally essential amino acid in critical care therapy 2, 3, 4
- Glutamine increases intestinal cellularity, as it is essential for maintaining intestinal integrity and function 3, 4, 5
- Glutamine is not an essential amino acid under normal conditions, but it can become essential in catabolic or hypercatabolic situations 6, 3, 4
- Glutamine is a substrate for gluconeogenesis, although this is not its primary function in the body 6, 4
Clinical Relevance of Glutamine Supplementation
- Glutamine supplementation is recommended for critically ill patients, as it can help maintain intestinal function and prevent atrophy 2, 3, 5
- Glutamine dipeptide-supplemented parenteral nutrition can maintain intestinal function in critically ill patients 5
- The beneficial effects of glutamine supplementation on immune function and intestinal health are well established, although more research is needed to determine the optimal dosage and administration route 6, 3, 4