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Fish Protein Decreases Serum Cholesterol in Rats by Inhibition of Cholesterol and Bile Acid Absorption
Author(s) -
Hosomi Ryota,
Fukunaga Kenji,
Arai Hirofumi,
Kanda Seiji,
Nishiyama Toshimasa,
Yoshida Munehiro
Publication year - 2011
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2011.02130.x
Subject(s) - cholesterol , casein , excretion , bile acid , medicine , chemistry , endocrinology , sodium cholate , feces , digestion (alchemy) , absorption (acoustics) , biochemistry , biology , chromatography , microbiology and biotechnology , physics , acoustics
Fish protein has been shown to decrease serum cholesterol content by inhibiting absorption of cholesterol and bile acid in laboratory animals, though the mechanism underlying this effect is not yet fully understood. The purpose of this study was to elucidate the mechanism underlying the inhibition of cholesterol and bile acid absorption following fish protein intake. Male Wistar rats were divided into 2 dietary groups of 7 rats each, 1 group receiving a diet consisting of 20% casein and the other receiving a diet consisting of 10% casein and 10% fish protein. Both experimental diets also contained 0.5% cholesterol and 0.1% sodium cholate. After the rats had been on their respective diets for 4 wk, their serum and liver cholesterol contents and fecal cholesterol, bile acid, and nitrogen excretion contents were measured. Fish protein consumption decreased serum and liver cholesterol content and increased fecal cholesterol and bile acid excretion and simultaneously increased fecal nitrogen excretion. In addition, fish protein hydrolyzate prepared by in vitro digestion had lower micellar solubility of cholesterol and higher binding capacity for bile acids compared with casein hydrolyzate. These results suggest that the hypocholesterolemic effect of fish protein is mediated by increased fecal cholesterol and bile acid excretion, which is due to the digestion products of fish protein having reduced micellar solubility of cholesterol and increased bile acid binding capacity. Practical Application: Fish protein decreased serum and liver cholesterol content and increased fecal cholesterol and bile acid excretion and simultaneously increased fecal nitrogen excretion. In addition, fish protein hydrolyzate prepared by in vitro digestion had lower micellar solubility of cholesterol and higher binding capacity for bile acids compared with casein hydrolyzate. These results suggest that the hypocholesterolemic effect of fish protein is mediated by increased fecal cholesterol and bile acid excretion, which is due to the reduced micellar solubility of cholesterol and increased bile acid binding capacity of the digestion products of fish protein. Fish protein intake is effective for improving blood cholesterol level and may have a beneficial effect for hypercholesterolemia patients. We conclude that a highly functional alternative diet could be recommended for such patients as a means of promoting health, based on the results of this study.