A specialized immunonutrition supplement can be administered to a surgical patient to reduce post-operative complications by restraining the expansion of myeloid-derived suppressor cells. The supplement includes one or more of L-arginine, omega-3 fatty acids, vitamin A, and dietary nucleotides, preferably all four of these compounds. The supplement is administered to the patient at least once per day for a time period extending from a pre-operative day that is three to seven days prior to a bladder surgery of the patient to a post-operative day that is three to seven days after the bladder surgery. The supplement can be administered to treat or prevent post-operative paralytic ileus in a bladder cancer patient; treat or prevent surgery-induced, inflammation-induced or cancer-induced cachexia; reduce the incidence of chronic infections resulting from expansion of myeloid-derived suppressor cells in a patient; and/or reduce mRNA expression of pro-inflammatory cytokines in a patient.