To discover whether an Omega-3 fatty acid (eicosapentaenoic acid/EPA and docosahexaensyre/DHA) enriched nutritional supplement given 7 days preoperatively and 7 days postoperatively may reduce the frequency of postoperative infectious complications defined as: pneumonia, wound infection, urinary tract infection, peritonitis (including anastomotic leakage) and septic conditions of any cause in patients who undergo elective operations for colorectal cancer compared with a nutritional preparation that is identical apart from the EPA content.

Several earlier studies indicate that perioperative supplements of Omega-3 fatty acids can reduce the risk of postoperative complications after major surgery through an immune modulating effect in the form of a downward adjustment of the inflammatory response. (1-7) The interpretation of these studies is made more difficult by differences in their method of administration (parentally/enterally), differences in the time of the intervention (preoperative/postoperative) and differences in the selection of patients (malnourished cancer patients / upper GI cancer patients/mixed surgical patients) and finally because many of the studies deal with a so-called immune modulating preparation containing a mixture of arginine, Omega-3 fatty acids and ribonucleic acid.

The biological effects of fish oils are related to their content of such things as Omega-3 fatty acids that can be incorporated in cell membranes where they influence receptor function, enzyme activity and the production of lipid mediators. The cells from the immune system perform their functions through membrane-associated activities like secretion of cytokines, antibodies, lymphocyte transformation and contact lysine. These functions can be affected by changes in the membrane structure. (7;8) Besides the effect parameter of postoperative septic complications, many of these studies use pseudoparameters such as length of stay, need for respirator treatment, time in intensive care as well as a wide range of biochemical changes whose relevance to the clinic process can be difficult to assess. (1-7;9-13;). It is well-known that early enteral nutrition reduces the risk of postoperative complications (14; 15). Many of the aforementioned studies similarly point to a benefit from using Omega-3 fatty acid enriched nutritional preparations preoperatively. There is now a commercially manufactured nutritional preparation for peroral consumption containing Omega-3 fatty acids - Supportan (Fresenius-Kabi). The preparation is more energy intensive than similar drink preparations, but does not otherwise differ in composition from standard preparations. It is approved by the Danish Veterinary and Food Administration for this study.

In 2 x 200ml of Supportan 3 g EPA and DHA are given daily. In other studies up to 10 g have been given daily without side effects. (6; 16)

Inclusion Criteria:

• Adult patients for elective colorectal resection for cancer, ASA group 1-3 (see annex)

Exclusion Criteria:

• Diabetes Mellitus
• Alcohol consumption > 5 drinks per day
• Acute operation
• Non Danish speakers
• Patients with untreated psychiatric conditions
• Pregnant or breast-feeding women
• Patients with ICD-pacemaker
• Patients with reduces kidney function and immunosuppressed patients
• patients that eat or drink omega-3 fatty acids
• patients operated for 2 different cancers in 1 operation