Overton P D, Furlonger N, Beety J M, Chakraborty J, Tredger J A, Morgan L M
Biomedical Research Division, School of Biological Sciences, University of Surrey, Guildford.
Br J Nutr. 1994 Sep;72(3):385-95. doi: 10.1079/bjn19940041.
This study investigates the mechanisms of action for the hypocholesterolaemic effects of sugar-beet fibre (SBF) and guar gum. Four groups of ten male Wistar rats were fed ad lib. on test diets containing either 100 g SBF or guar/kg, or control diets containing 100 g cellulose or wheat bran/kg for 28 d. Food intake, weight gain and food consumption ratios were unaffected by the diets. Circulating cholesterol and hepatic cholesterol concentrations were significantly lower in both SBF- and guar-fed groups compared with either cellulose- or bran-fed animals. Circulating triacylglycerol concentrations were significantly lower in SBF- and guar-fed animals, but total hepatic lipid concentrations and hepatic and adipose tissue lipogenesis rates were unaffected by the diets. Hepatic cholesterol-7 alpha-hydroxylase (EC 1.14.13.17) activities were significantly higher in the guar-fed animals compared with cellulose or bran control groups. Hepatic 3-hydroxy-3-methylglutaryl-CoA reductase (EC 1.1.1.88) activities were unaffected. Circulating bile acid concentrations were significantly lower in SBF- and guar-fed animals and faecal bile acid output was significantly higher in the guar-fed group compared with bran- or cellulose-fed groups. This study supports the hypothesis that guar exerts its hypocholesterolaemic effect via intraluminal bile acid binding and loss of cholesterol from increased faecal bile acid excretion. The mechanism of action for the hypocholesterolaemic effect of SBF is less clear; the results of the present study point to a mechanism involving disruption of the enterohepatic bile acid circulation, possibly via changes in the rate of absorption of dietary lipid.
本研究调查了甜菜纤维（SBF）和瓜尔豆胶降胆固醇作用的机制。将四组每组十只雄性Wistar大鼠随意喂食含100 g SBF或瓜尔豆胶/千克的试验日粮，或含100 g纤维素或麦麸/千克的对照日粮，持续28天。日粮对食物摄入量、体重增加和食物消耗率没有影响。与喂食纤维素或麦麸的动物相比，喂食SBF和瓜尔豆胶的两组动物的循环胆固醇和肝脏胆固醇浓度均显著降低。喂食SBF和瓜尔豆胶的动物的循环三酰甘油浓度显著降低，但日粮对肝脏总脂质浓度以及肝脏和脂肪组织的脂肪生成率没有影响。与纤维素或麦麸对照组相比，喂食瓜尔豆胶的动物的肝脏胆固醇-7α-羟化酶（EC 1.14.13.17）活性显著更高。肝脏3-羟基-3-甲基戊二酰辅酶A还原酶（EC 1.1.1.88）活性不受影响。与喂食麦麸或纤维素的组相比，喂食SBF和瓜尔豆胶的动物的循环胆汁酸浓度显著降低，且喂食瓜尔豆胶的组的粪便胆汁酸排出量显著更高。本研究支持以下假设：瓜尔豆胶通过肠腔内胆汁酸结合以及粪便胆汁酸排泄增加导致胆固醇流失来发挥其降胆固醇作用。SBF降胆固醇作用的机制尚不清楚；本研究结果表明其机制可能涉及肠肝胆汁酸循环的破坏，可能是通过饮食脂质吸收速率变化实现的。
