Cardiovascular disease is the most important cause of death in the western countries and it is strongly associated with hypercholesterolemia. Decreasing serum cholesterol is, therefore, very important to prevent cardiovascular disease. One of the beneficial health effects related to probiotics is their ability to reduce serum cholesterol. The mechanism of action of probiotics on cholesterol reduction is unclear, although a number of possible mechanisms have been proposed. Two main mechanisms have been proposed. The first one is the reduction of absorption of cholesterol from the intestinal tract and the other one is bile salt deconjugation by the bacteria.