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

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.

Potato Pulps Lowered the Serum Cholesterol and Triglyceride Levels in Rats

“…Retrograde starch is a kind of resistant starch that has resistance against amylase, and may act like dietary fiber in the digestive tract. Actually, we have previously reported that resistant starches of beans reduce serum cholesterol and triglyceride (TG) levels in rats (8)(9)(10)(11). It is suggested that the cholesterol-lowering function by the resistant starches of beans was due to cecal fermentation products such as short chain fatty acid (SCFA) and increased fecal steroid excretion (8)(9)(10).…”

Suppression of Serum Cholesterol Levels in Mice by Adzuki Bean Polyphenols

“…While no significant difference was found in HDL cholesterol level between the two groups, VLDL + IDL + LDL cholesterol level was significantly lower in the experimental group than in the control group (Table 2). It was therefore suggested, as in the case of the mice given feed supplemented with Adzuki re-sistant starch or enzyme-treated Adzuki resistant starch (Han et al, 2003a(Han et al, , 2003b, that the lower total cholesterol level was attributable to the reduction in VLDL + IDL + LDL cholesterol level. In addition, the AI in the experimental mice was significantly lower than that in the control mice (Table 1).…”

“…Adzuki beans contain dietary fiber, saponins, and polyphenols (Kojima et al, 1989;Kojima et al, 2006aKojima et al, , 2006b). We previously reported that feed containing supplemental resistant starch from Adzuki beans or enzyme-treated Adzuki resistant starch reduced serum cholesterol levels in rats (Han et al, 2003a(Han et al, , 2003b. In this two-week study, the ability of an Adzuki polyphenol (Adzuki-PP) solution to lower serum cholesterol was investigated in mice fed a high-cholesterol diet and administered an Adzuki-PP solution daily via a catheter.…”

Hypolipidemic Effects of Starch and γ-Oryzanol fromwx/aeDouble-Mutant Rice on BALB/c.KOR-ApoeshlMice

“…Slowly digestible starch consists of amorphous and raw starches with a type A or C crystalline structure, or type B starch in granule or retrograded form. 4) Resistant starch (RS) cannot be digested in the small intestine and is effective against hyperglycaemia, [5][6][7] hypercholesterolaemia, 8,9) and fat accumulation. 10) RS can be classified into four types.…”