Kayashita J, Shimaoka I, Nakajoh M, Yamazaki M, Kato N
Development, Health Care, Kissei Pharmaceutical Co., Ltd., Yoshino, Matsumoto 399, Japan.
J Nutr. 1997 Jul;127(7):1395-400. doi: 10.1093/jn/127.7.1395.
Buckwheat protein product (BWP) has a strong hypocholesterolemic activity in rats fed a cholesterol-enriched diet. In this study, we examined the influence of BWP on fecal excretion of sterols and nitrogen in rats fed a diet containing 5 g/kg cholesterol and 1.25 g/kg sodium cholate, and we examined whether the cholesterol-lowering activity of BWP is due to its low digestibility. In Experiment 1, rats fed BWP for 3 wk had significantly lower concentrations of plasma cholesterol and enhanced excretion of fecal total neutral sterols and nitrogen compared with rats fed casein. There was a significant correlation between fecal total neutral sterols and nitrogen (r = 0.89, P < 0.01). Fecal excretion of acidic sterols was unaffected by BWP. In Experiment 2, plasma cholesterol in rats fed trypsin-digested BWP for 2 wk was significantly higher than that in rats fed intact BWP. In Experiment 3, rats were fed BWP, low-molecular-weight fraction of the digest of BWP (LMF ) or high-molecular-weight fraction of the digest of BWP (HMF ) for 3 wk. Plasma cholesterol was lower in the BWP group than in the LMF group (P < 0.05), whereas that in the HMF group was intermediate. The in vitro digestibility of BWP with pepsin and pancreatin was significantly lower than that of casein. The results suggest that the cholesterol-lowering effect of BWP is mediated by higher fecal excretion of neutral sterols and that lower digestibility of BWP is at least partially responsible for the effect.
在喂食富含胆固醇饮食的大鼠中，荞麦蛋白产品（BWP）具有很强的降胆固醇活性。在本研究中，我们检测了BWP对喂食含5 g/kg胆固醇和1.25 g/kg胆酸钠饮食的大鼠粪便中固醇和氮排泄的影响，并研究了BWP的降胆固醇活性是否因其消化率低所致。在实验1中，与喂食酪蛋白的大鼠相比，喂食BWP 3周的大鼠血浆胆固醇浓度显著降低，粪便总中性固醇和氮的排泄增加。粪便总中性固醇与氮之间存在显著相关性（r = 0.89，P < 0.01）。BWP对酸性固醇的粪便排泄没有影响。在实验2中，喂食胰蛋白酶消化的BWP 2周的大鼠血浆胆固醇显著高于喂食完整BWP的大鼠。在实验3中，大鼠分别喂食BWP、BWP消化物的低分子量部分（LMF）或BWP消化物的高分子量部分（HMF）3周。BWP组的血浆胆固醇低于LMF组（P < 0.05），而HMF组的血浆胆固醇处于中间水平。BWP在体外被胃蛋白酶和胰酶消化的消化率显著低于酪蛋白。结果表明，BWP的降胆固醇作用是通过中性固醇粪便排泄增加介导的，且BWP较低的消化率至少部分导致了这种作用。
