Immunonutrition within enhanced recovery after surgery (ERAS): an unresolved matter

Preoperative malnutrition because of poor oral intake significantly increases the risk of adverse events after surgery and leads to increased length of stay. While immunonutrition has been utilized in the non-ERAS setting, its utility in both minimally invasive surgery and ERAS pathway procedures remain poorly defined. There are at least ten meta-analyses regarding the assessment of immunonutrition, but virtually, all of these were performed in an era prior to minimally invasive surgery, adoption of enhanced recovery protocols, and an understanding of the assessment and physiology of sarcopenia. In terms of immunonutrition within an ERAS pathway, the few studies that have been published have severe flaws in design and sample, bringing their overall conclusion into question. Furthermore, the optimal components of immunonutrition have yet to be adequately determined and may vary for patients based on comorbidities as well as the proposed procedures. Risk stratification based on markers of nutritionally deficient states such as image assessed sarcopenia, Glasgow Prognostic Score, prognostic nutrition index, or assessment of methylarginines are needed prior to the initiation of any such immunotherapy. Lastly, there is a need for properly designed randomized control trials that stratify patients appropriately and determine the optimal timing, composition, and duration of immunotherapy.