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.