50-60 patients, who will undergo aortic valve surgery, will be asked to volunteer our study. The patients will be randomized into three groups: (A) a group consuming margarine containing daily 2 grams plant stanols, (E) a group consuming margarine containing daily 2 grams of plant sterols, (C) a control group consuming margarine without any plant sterols or stanols. The dietary intervention will last for 4 to 8 weeks from the randomization to the operation.