Enzyme-resistant fractions of beans lowered serum cholesterol and increased sterol excretions and hepatic mRNA levels in rats

Lipids. 2003 Sep;38(9):919-24. doi: 10.1007/s11745-003-1145-2.

Abstract

Feeding rats beans with resistant starch reduces their serum cholesterol concentration; however, the mechanism by which this occurs is not fully understood. We examined the effects of enzyme-resistant fractions of adzuki (Vigna angularis) and tebou (Phaseolus vulgaris, var.) beans on serum cholesterol and hepatic mRNA in rats. Rats were fed a cholesterol-free diet with 50 g of cellulose powder (CP)/kg, 50 g of an enzyme-resistant fraction of adzuki starch (AS)/kg, or 50 g of an enzyme-resistant fraction of tebou starch (TS)/kg diet for 4 wk. There were no significant differences in body weight, liver weight, and cecum contents among the groups, nor was there a significant difference in food intake among the groups. The levels of serum total cholesterol, VLDL + intermediate density lipoprotein + LDL-cholesterol, and HDL cholesterol in the AS and TS groups were significantly (P < 0.05) lower than in the CP group throughout the feeding period. Total hepatic cholesterol in the CP group was significantly (P < 0.05) lower than in the AS and TS groups, fecal cholesterol excretion in the TS group was significantly (P < 0.05) greater than in the CP and AS groups, and the fecal total bile acid concentrations in the AS and TS groups were significantly (P < 0.05) higher than in the CP group. Cecal acetate, propionate, and n-butyrate concentrations in the AS and TS groups were significantly (P < 0.05) higher than in the CP group. The level of hepatic scavenger receptor class B1 (SR-B1) mRNA in the TS group was significantly (P < 0.05) higher than in the CP group, and the levels of hepatic cholesterol 7alpha-hydroxylase mRNA in the AS and TS groups were significantly (P < 0.05) higher than in the CP group. These results suggest that AS and TS have a serum cholesterol-lowering function due to the enhanced levels of hepatic SR-B1 and cholesterol 7alpha-hydroxylase mRNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bile Acids and Salts / analysis
  • Body Weight / drug effects
  • Cholesterol / analysis
  • Cholesterol / blood*
  • Cholesterol 7-alpha-Hydroxylase / genetics
  • Diet
  • Fabaceae / chemistry*
  • Fatty Acids / analysis
  • Fatty Acids / chemistry
  • Feces / chemistry
  • Feeding Behavior / drug effects
  • Gastrointestinal Contents
  • Hydrogen-Ion Concentration
  • Liver / drug effects*
  • Liver / enzymology
  • Liver / metabolism
  • Male
  • Organ Size / drug effects
  • Pepsin A / metabolism*
  • Plant Extracts / chemistry
  • Plant Extracts / pharmacology*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism*
  • Rats
  • Rats, Inbred F344
  • Sterols / blood
  • Sterols / metabolism*
  • Time Factors

Substances

  • Bile Acids and Salts
  • Fatty Acids
  • Plant Extracts
  • RNA, Messenger
  • Sterols
  • Cholesterol
  • Cholesterol 7-alpha-Hydroxylase
  • Pepsin A