ObjectiveTo evaluate the effect of early postoperative feeding with a nutritionally complete enteral diet supplemented with the nutrients arginine, ribonucleic acid (RNA), and omega-3 fatty acids on the immune function in patients undergoing surgery for upper gastrointestinal (GI) malignancies.DesignProspective, randomized, placebo-controlled, double-blind study.SettingSurgical intensive care unit (ICU) in a German university hospital.PatientsForty-two consecutive patients receiving an enteral diet via needle catheter jejunostomy after GI surgery for cancer.InterventionsPatients were randomized to receive either the arginine, RNA, and omega-3 fatty acids supplemented diet or an isocaloric and isonitrogenous placebo diet. Early enteral nutrition was started on postoperative day 1 in the surgical ICU with 20 mL/hr and progressed to the optimal goal of 80 mL/hr by postoperative day 5.Measurements and Main ResultsClinical examination and adverse GI symptoms were recorded on a daily basis. Body weight was determined twice weekly. Immunoglobulin concentrations were determined by laser nephelometry. Interferon-gamma concentrations were measured with a modified enzyme-linked immunosorbent assay method. Fluorescence-activated cell scan flow cytometry was performed to analyze B cells, T lymphocytes and their subsets. Clinical patient characteristics and mean caloric intake were similar between the two groups and both formulas were well tolerated. The number of T lymphocytes and their subsets, helper T cells (CD4) and activated T cells (CD3, HLA-DR), were significantly higher in the supplemented diet group on postoperative days 10 and 16 (p < .05). Mean interferon-gamma concentration after phytohemagglutinin stimulation was higher in the supplemented diet group on postoperative day 16. In the supplemented diet group, mean immunoglobulin M concentrations were significantly higher on postoperative day 10 and mean immunoglobulin G concentrations were higher on postoperative day 16 (p < .05) compared with the results in the placebo group. B-lymphocyte indices were significantly higher in the supplemented vs. the placebo diet group on postoperative days 7 and 10 (p < .05).ConclusionsSupplementation of enteral diet with arginine, RNA, and omega-3 fatty acids in the early postoperative time period improves postoperative immunologic responses and helps to overcome more rapidly the immunologic depression after surgical trauma.(Crit Care Med 1995; 23:652-659)