Although several studies have reported the effects of immunonutrition on clinical outcomes, detailed mechanisms of immunonutrition after an operation are still unclear. It was recently reported that resolvin E1, a novel lipid mediator generated from eicosapentaenoic acid (EPA), activates factors that reduce inflammation. This randomized clinical trial was designed to investigate not only the effect of immunonutrition on postoperative complications but also the participation of resolvin E1 on anti-inflammatory effects of immunonutrition in patients undergoing major hepatobiliary resection.

Forty patients who underwent major hepatobiliary resection were divided into 2 groups. Twenty patients received oral supplementation enriched with EPA, arginine, and nucleotides before the operation (group IN). Twenty patients (control group) received no artificial nutrition before the operation (group C).

The rate of infectious complications and severity of complications in group IN was significantly lower than in group C (P < .05). Immediately after the operation, plasma resolvin E1 levels were significantly higher in group IN than in group C (P < .05), and plasma interleukin-6 levels were significantly lower in group IN than in group C (P < .05). Preoperative serum EPA levels correlated with plasma resolvin E1 levels immediately after the operation. Plasma resolvin E1 levels correlated with plasma interleukin-6 levels immediately after the operation.

Preoperative immunonutrition reduced inflammatory responses and protected against the aggravation of postoperative complications in patients undergoing major hepatobiliary resection. Resolvin E1 may play a key role in the resolution of acute inflammation when immunonutrition is supplemented with EPA. (ClinicalTrials.gov Identifier: NCT01256047.)