Transworld Research Network 37/661 (2), Fort P.O. Trivandrum-695 023 Kerala, India Biochemical Aspects of Human Nutrition, 2010: 223-242 ISBN: 978-81-7895-478-3 Editors: Luciana Avigliano and Luisa Rossi 12. Plant sterols, cholesterol metabolism and related disorders Laura Calpe-Berdiel 1,2 , Jesús Méndez-González 1,4 , Gemma Llaverias 1,2,3 Joan Carles Escolà-Gil 1,2,3 and Francisco Blanco-Vaca 1,3,4 1 Servei de Bioquímica, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; 2 Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; 3 CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Spain; 4 Departament de Bioquímica i Biologia Molecular Universitat Autònoma de Barcelona, Barcelona, Spain Abstract. Plant sterols and stanols are known to reduce serum LDL-cholesterol levels, and food products containing these plant compounds are widely used as a therapeutic dietary option to reduce plasma cholesterol and atherosclerotic risk. The cholesterol-lowering action of plant sterols is thought to occur, at least in part, through competition with dietary and biliary cholesterol for intestinal absorption in mixed micelles. However, recent evidence suggests that plant sterols may regulate proteins inolved in cholesterol metabolism both in enterocytes and hepatocytes. Important advances in the understanding of intestinal sterol absorption have provided potential molecular targets of phytosterols. Nevertheless, conclusive studies using ABCA1 and ABCG5/G8- deficient mice have demonstrated that the phytosterol-mediated inhibition of intestinal cholesterol absorption is independent of these ABC transporters. Other reports have proposed a plant sterol action on cholesterol esterification and lipoprotein assembly, cholesterol synthesis and apolipoprotein (apo) B100- containing lipoprotein removal. Further, although most studies have focused on the cholesterol-lowering activity of phytosterols, other biological actions, such as immunomodulation and anticancer properties, are increasingly being ascribed to these plant sterol compounds. On the other hand, a number of studies have raised the possibility that circulating plant sterols may be a risk factor contributing to the pathogenesis of atherosclerosis. Evidence in support of this hypothesis stems mainly from observations in sitosterolemic subjects who hyperabsorb plant sterols and suffer Correspondence/Reprint request: Dr. Francisco Blanco-Vaca, Hospital de la Santa Creu i Sant Pau, Servei de Bioquímica, C/ Antoni M. Claret 167, 08025 Barcelona, Spain. E-mail: fblancova@santpau.cat