Sterols are basic components of cell membranes in animal and plant organisms. So far, almost 40 types of plant sterols have been identified, and, among them, the most known and the most commonly occurring are: β-sitosterol, kampesterol, and stigmasterol. Stanols constitute their saturated type obtained during the hydrogenation of sterols. Phytosterols are natural plant components of, for example: soybeans, plant oils, rice, and pine wood. Small amounts of phytosterols are also in nuts, vegetables, and fruits. An adequate measured quantity of plant sterols is able to essentially reduce the cholesterol level in blood. The mechanism of their activity consists in decreasing the intestinal absorption of cholesterol by replacing it in micelles. Extensive clinical research projects showed that a dose of 2 – 3 g sterols per day caused the level of total cholesterol to be reduced by about 10 % and the LDL fraction to be decreased by ca. 15 %. The intake of those compounds reduces the risk of heart attack and prevents atherosclerosis and coronary heart disease. Therefore, plant sterols are more and more often added to food products, among other things to margarines, oils, yogurts, ripening cheeses, bakery products, muesli, juices and fruit beverages.