Background: Delirium and long-term cognitive dysfunction (CD) are important complications of major surgery and intensive care treatment. Delirium is associated with increased mortality and CD has an important impact on mortality, independency, social interactions, and quality of life. Delirium is an important risk factor for the development of long-term CD. Particularly, patients aged 65 or older undergoing cardiac surgery are at a high risk of developing these problems. There are data suggesting that inflammation plays a key role in the development of delirium and possibly CD. It has been shown that n-3 fatty acids modulate the immune response of patients and have beneficial effects in abdominal surgery.

Working hypothesis: 1. Administration of n-3 enriched nutrition therapy including will modulate the inflammatory response and improve cognitive function after cardiac surgery. Specific Aims: This project will test the impact of perioperative enteral n-3 fatty acids ProSure, Abbott Nutrition) in elderly patients undergoing elective cardiac surgery. Primary endpoint is CD one week postoperatively. Methods: The investigators will investigate 400 patients aged 65 or older undergoing elective cardiac surgery. Half of these patients will receive supplementary of n-3 fatty acids to modulate the inflammatory response; the other half will receive an isocaloric nutritional supplement without n-3 fatty acids (Ensure Plus, Abbott Nutrition). Otherwise the treatment of the patients will not be influenced by this study. Cognitive function will be assessed preoperatively, 7 days and three months postoperatively. C-reactive protein, IL-6, IL-8, IL-10, S-100B, and neuron specific enolase will be monitored as markers of systemic inflammation and delirium.