New margarines containing plant sterols and stanols claim to lower serum cholesterol concentrations.
However, these products cost three to four times more than conventional margarines or butter. Law reviewed the results of randomized trials to assess the ability of margarine or butter containing plant stanols or sterols to lower serum cholesterol concentrations. Sterols are an important component of cell membranes and are produced by plants and animals, while cholesterol is exclusively an animal product. Plant sterols reduce serum concentrations of cholesterol by lowering cholesterol absorption from the gut by competing at the mucosal cell level for the limited space in the mixed micelles that transport lipids across gastrointestinal membranes. Because fats are necessary to solubilize sterols, margarines are an ideal vehicle.