Rice Protein Extracted by Different Methods Affects Cholesterol Metabolism in Rats Due to Its Lower Digestibility

• Main Authors: Hongbo Liu, Lanwei Zhang, Fuping Xu, Yan Zhang, Wei Qiu, Tong Xu, Jiahou Chen, Lin Yang
• Format: Article
• Language: English
• Published: MDPI AG 2011-11-01
• Series: International Journal of Molecular Sciences
• Subjects: rice protein; digestibility; cholesterol; absorption; rats
• Online Access: http://www.mdpi.com/1422-0067/12/11/7594/

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.