['Perioperative administration of immunoenriched diets attenuates the perioperative inflammatory response and reduces postoperative infection complications. However, many questions still remain unresolved in this area, such as the length of diet administration, diet composition, and the mechanisms involved. We performed an open, randomized, triple-arm study comparing the effect of two perioperative feeding regimens with a postoperative one.', '46 candidates for major elective surgery for malignancy in the upper gastrointestinal tract were randomized to drink preoperatively either 1 L of an immunoenriched formula (Impact) for 5 days (IEF group) or 1 L of Impact plus (Impact enriched with glycine) for 2 days (IEF plus group). The same product as the patient received preoperatively was given to both groups for 7 days postoperatively. In the control group (CON group), patients only received Impact for 7 days postoperatively; there was no preoperative treatment. The main outcome measures were postoperative C-reactive protein (CRP) serum levels.', 'In the two preoperatively supplemented groups (treatment groups), perioperative endotoxin levels, CRP (postoperative day 7), and TNF-alpha (postoperative days 1 and 3) levels were significantly lower compared to the CON group (p < .01). Furthermore, the length of postoperative IMU/ICU stay (Impact 1.9 +/- 1.3 days; Impact plus 2.2 +/- 1.1 days; control group 5.9 +/- 0.8 days) and length of hospital stay (Impact 19.7 +/- 2.3 days; Impact plus 20.1 +/- 1.3 days; control group 29.1 +/- 3.6 days) were both reduced in the treatment groups compared to the control group. Infectious complications (Impact 2/14 (14%); Impact plus 5/17 (29%); control group 10/15 (67%)) also showed a trend toward reduction in the treatment groups.'] Does preoperative immunonutrition suppress perioperative inflammatory response in patients with major abdominal surgery-a randomized controlled pilot study?