Immunonutrition and critical illness: an update.

Dietary supplementation with nutrients that have physiologic effects on immune function has been shown to be beneficial in subsets of patients with surgical and medical critical illness. However, several meta-analyses have suggested potential harm when immune nutrients are used inappropriately. This has led to concern among clinicians that in turn has curtailed the more widespread use of immunonutrition as a therapeutic modality. This article discusses the mechanisms by which immune nutrients can be used to modulate alterations in innate and acquired immunity associated with critical illness. In addition, recent evidence-based clinical practice guidelines for use of immunonutrition in adults is reviewed as a means to clarify some of the more controversial issues and provide a "roadmap" for the practitioner. 2010 Elsevier Inc. All rights reserved.