title: Rice protein extracted by different methods affects cholesterol metabolism in rats due to its lower digestibility.
abstract: To elucidate whether the digestibility is responsible for the hypocholesterolemic action of rice protein, the effects of rice proteins extracted by alkali (RP-A) and α-amylase (RP-E) on cholesterol metabolism were investigated in 7-week-old male Wistar rats fed cholesterol-free diets for 3 weeks. The in vitro and in vivo digestibility was significantly reduced by RP-A and RP-E as compared to casein (CAS). The digestibility was lower in RP-E than that of RP-A. Compared with CAS, the significant cholesterol-lowering effects were observed in rats fed by RP-A and RP-E. Fecal excretion of bile acids was significantly stimulated by RP-E, but not by RP-A. The apparent cholesterol absorption was more effectively inhibited by RP-E than RP-A because more fecal neutral sterols were excreted in rats fed RP-E. There was a significant correlation between protein digestibility and cholesterol absorption (r = 0.8662, P < 0.01), resulting in a significant correlation between protein digestibility and plasma cholesterol level (r = 0.7357, P < 0.01) in this study. The present study demonstrates that the digestibility of rice protein affected by extraction method plays a major role in the modulation of cholesterol metabolism. Results suggest that the hypocholesterolemic action induced by rice protein with lower digestibility primarily contribute to the inhibition of cholesterol absorption.
authors.affiliation: School of Food Science and Engineering, Harbin Institute of Technology, 73 Huanghe Road, Harbin 150090, China; E-Mails:  lanweizhang@yahoo.com.cn  (L.Z.);  chinacentre@163.com  (F.X.).
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Jiahou
authors.initials: J
authors.lastname: Chen
authors.forename: Tong
authors.initials: T
authors.lastname: Xu
authors.forename: Wei
authors.initials: W
authors.lastname: Qiu
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Lanwei
authors.initials: L
authors.lastname: Zhang
authors.forename: Fuping
authors.initials: F
authors.lastname: Xu
authors.forename: Hongbo
authors.initials: H
authors.lastname: Liu
mesh_terms: D065567:Absorption, Physiological; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism; D002364:Caseins / Q000008:administration & dosage; D002784:Cholesterol / Q000097:blood / Q000378:metabolism*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000737:chemistry; D004063:Digestion / Q000187:drug effects*; D005243:Feces / Q000737:chemistry; D008099:Liver / Q000378:metabolism; D008297:Male; D012275:Oryza / Q000737:chemistry*; D010940:Plant Proteins / Q000008:administration & dosage* / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000596:Amino Acids; D001647:Bile Acids and Salts; D002364:Caseins; D004044:Dietary Proteins; D010940:Plant Proteins; D002784:Cholesterol