Glutamine and Arginine supplementation of enteral feeding in critically ill patients

A variety of enteral feeding formulations were developed for patients with critical illnesses. To the best of our knowledge, no such formulation demonstrated a beneficial effect on clinical outcomes. As a result, disease specific enteral formulation is not recommended over the traditional types of enteral nutrition. However, the enteral nutrition enriched with omega-3 fatty acids may be beneficial to patients with ARDS.

 

Glutamine

Glutamine is a precursor for nucleotide synthesis and an important fuel source for rapidly dividing cells that is rapidly depleted in hypercatabolic patients.

It is nonessential amino acid that can be synthesized from glutamate and glutamic acid by glutamate ammonia ligase. Glutamine is an important fuel source for the small intestine. It was proposed that glutamine is necessary for the maintenance of normal intestinal morphology and function in the absence of luminal nutritients. It was suggested that both glutamine supplemented parenteral and enteral nutrition may prevent bacterial translocation via preservation and augmentation of small bowel villus morphology, intestinal permeability and intestinal immune function. However, it is unclear whether clinically relevant bacterial translocation even occurs in humans, much less whether there is any value in the prevention of such occurrences.

 

Glutamine supplementation of enteral nutrition has been evaluated in more than 30 controlled trials with critically ill patients, most of which had significant methodologic problems or were too small to make definitive conclusions.

Meta-analyses of RCTs that compared enteral nutrition with and without glutamine, there was no difference in mortality or infectious complications. In a recent update (2013), the absence of mortality benefit persisted among patients who received glutamine enriched enteral nutrition (www.criticalcarenutrition.com).

 

Based on 2 level 1 and 7 level 2 studies, enteral glutamine should be considered in burn and trauma patients. There are insufficient data to support glutamine enriched enteral nutrition for routine use in most critically ill patients because clinical trials have not found consistent improvement in clinical outcomes.(Canadian Clinical Practice Guidelines 2013). Given the harm associated with glutamine in patients with multi-organ failure, it is considered unsafe to administer EN glutamine even in burns/trauma patients with MOF (REDOXs trial). There for the CPG strongly against any glutamine to be used in critically ill patients with multi-organ failure.

Glutamine is metabolized by the liver, kidneys and splanchnic tissue into glutamate and ammonia. Accumulation of glutamine and its byproducts may lead to adverse effects such as encephalopathy.

 

 

Arginine

Arginine is considered conditionally essential during critical illness because it is utilized more quickly. It is required for normal immune function and healing. It has improtant roles in nitrogen metabolism, ammonia metabolism and generation of NO. Despite this, aginine enriched enteral nurtition is NOT recommended for routine use in critically ill patients because clinical outcomes have been inconsistent.

Meta-analyses that compared arginine enriched enteral nurtition to standard enteral nutrition in crtically ill patients found no effect on mortality and no effect on infectious complications. These results persisted in the recent update www.criticalcarenutrition.com. Based on 4 level 1 studies and 22 level 2 studies, diet supplemented with arginine and other select nutrients are not recommended to be used for critically ill patients.
Some studies suggested that arginine enriched enteral nutrition was potentially harmful (JPEN 2001).