Immunonutrition in Critical Illness: What Is the Role?

Acute illness-associated malnutrition leads to muscle wasting, delayed wound healing, failure to wean from ventilator support, and possibly higher rates of infection and longer hospital stays unless appropriate metabolic support is provided in the form of nutrition therapy. Agreement is still lacking about the value of individual immune-modulating substrates for specific patient populations. However, it has long been agreed that there are 3 primary targets for these substrates: 1) mucosal barrier function, 2) cellular defense function, and 3) local and systemic inflammation. These targets guide the multitude of interventions necessary to stabilize and treat the hypercatabolic intensive care unit patient, including specialized nutrition therapy. The paradigm shift that occurred 30 years ago created a unique role for nutrition as an agent to support host defense mechanisms and prevent infectious complications in the critically ill patient. This overview of immunonutrition will discuss the evidence for its role in critical illness today.