Objectives: We previously reported that omega-6 fat emulsion increases cytokine production in burned rats. Effects of soybean oil emulsion on surgical stress responses and lymphocyte function according to the surgical severity have not been studied in detail. We investigated the effects of soybean oil emulsion, which contains 50% omega-6 fatty acid, on postoperative stress responses and cell-mediated immune function according to the severity of surgical stress.
Methods: Eight patients who underwent gastric or colorectal surgery and nine who underwent esophagectomy were fed fat-free total parenteral nutrition. Ten patients who underwent gastric or colorectal surgery and seven who underwent esophagectomy were fed total parenteral nutrition with soybean oil emulsion. Total parenteral nutrition provided 1.5 g of protein and 40 kcal per kilogram every day from 7 d before surgery to postoperative day 14. Soybean oil emulsion (Intralipid) accounted for 20% of the total calories. Serum interleukin-6, C-reactive protein, glucagon, and concanavalin A- or phytohemagglutinin-stimulated lymphocyte proliferation were determined.
Results: In the group of moderately stressed patients, soybean oil emulsion did not amplify the measured levels. In the group of severely stressed patients, soybean oil emulsion amplified the level of serum interleukin-6 and decreased concanavalin A- or phytohemagglutinin-stimulated lymphocyte proliferation.
Conclusions: Soybean oil emulsion amplifies the stress responses and possibly suppresses cell-mediated immune function induced by surgical stress in severely stressed patients, but not in moderately stressed patients.