大豆蛋白降低人体血浆胆固醇浓度的作用途径(英文)

Effect of soybean protein in lowering human serum cholesterol

背景:多项实验表明同酪蛋白相比,大豆蛋白在动物包括人体内可以降低血浆胆固醇浓度,但其作用途径尚未阐明。目的:探讨摄入大豆蛋白后,人体血浆胆固醇浓度降低的可能作用途径。设计:观察对比实验。单位:沈阳医学院预防医学系营养与食品卫生学教研室。对象:实验于2002-03/05在沈阳医学院预防医学系营养与食品卫生学实验室完成。选择沈阳医学院健康大学生20名,男女各半,均自愿参加实验,并得到签名的书面同意书。年龄(21±1)岁,体质量指数为(22.3±3.0)kg/m2,血浆总胆固醇浓度在正常范围。将实验对象分为两组,既酪蛋白组和大豆蛋白组,每组10名。方法:依据中国营养学会1999年制定的《中国居民平衡膳食宝塔》和学生餐厅食谱编制基础膳食食谱。在摄入相同基础膳食的基础上,酪蛋白组和大豆蛋白组每人摄入酪蛋白和大豆蛋白30g/d,共摄入14d。在实验开始和结束时,测量两组实验对象的体质量,并采血测定血浆总胆固醇浓度;在实验结束前3d,收集每人的粪便,测定粪钙、磷、镁、脂类和胆汁酸含量,并进行比较分析。主要观察指标:①两组实验对象实验期间血浆总胆固醇浓度。②两组实验对象实验期间粪钙、磷、镁、脂类和胆汁酸排出量及相关和回归分析结果。结果:大豆蛋白组1名实验对象由于交通事故退出实验,酪蛋白组1名实验对象因对酪蛋白不耐受退出实验。两组均有9名实验对象进入结果分析。①两组实验对象实验期间血浆总胆固醇浓度比较:与实验开始时相比,实验14d后酪蛋白组血浆总胆固醇浓度升高了11%犤(3.7±0.47,4.1±0.61)mmol/L(Z=-2.668,P<0.01)犦,而大豆蛋白组仅升高了6%(P>0.05)。②两组实验对象实验期间粪钙、磷、镁、脂类和胆汁酸排出量比较:同酪蛋白组相比,大豆蛋白组的粪钙、磷和镁的排出量均明显增加,分别增加了60.3%,44.1%和55.0%(P<0.05～0.01);粪脂类和胆汁酸分别增加了33.6%和45.3%。③相关和回归分析:粪胆汁酸排出量同粪钙、磷、镁和脂类排出量呈显著正相关(t=3.173,3.448,2.411,2.122,P<0.05)。结论:大豆蛋白降低人体血浆胆固醇浓度的可能途径是增加了粪钙、磷、镁和胆汁酸的排出量。

BACKGROUND： Some studies indicate that compared with casein, intake of soybean protein lowers the concentration of serum cholesterol in animals including humans. However, the pathway of soybean protein＇s effect has not been revealed. OBJECTIVE： To investigate the possible pathway of the effect of soybean protein in lowering serum cholesterol concentration in humans. DESIGN： Controlled experiment. SETTING： Department of Nutrition and Food Health, Faculty of Preventive Medicine of Shenyang Medical College. PARTICIPANTS： The experiment was carried out in the Department of Nutrition and Food Health, Faculty of Preventive Medicine of Shenyang Medical College, from March to May 2002. Twenty healthy college students, 10 males and 10 females from Shenyang Medical College, participated in the experiment as volunteers. They gave their written consent before entry into the study. The average age of the participants was （20.7±1.1） years and body mass index （BMI） was （22.3±1：3.0） kg/m^2. The concentration of serum total cholesterol （TC） was within the normal range. They were distributed to 2 groups, namely casein group and soybean protein group with 10 students in each. METHODS： The recipes of basic diet for subjects were based on Chinese Balanced Diet Pagoda established by Chinese Nutrition Society in 1999 and the recipes of the Students＇ Canteen. The subjects in casein group or soybean protein group ingested 30 g of casein or soybean protein daily for 14 days, respectively, besides the same basic diet for each meal. On the first and last days of the experiment, their body mass was measured and blood samples were collected. The concentration of serum TC was assayed. Feces of the subjects were collected on the last 3 days of the trial and fecal excretions of lipids, calcium, phosphorus, magnesium and bile acids were measured. MAIN OUTCOME MEASURES： （1） The concentration of serum TC in subjects from both groups during the experiment. （2） The fecal excretions of calcium, phosphorus, magnesium, lipids and bile acids in subjects from both groups during the experiment. （3） Resuhs of correlation and regression analysis. RESULTS： One subject in soybean protein group was excluded from data analysis because of a traffic accident. One subject in casein group was excluded because of intolerance to casein. Therefore, data of 9 subjects from each group were computed. （1） The concentration of serum TC in subjects from both groups during the experiment： Compared with that on the first day of the trial, casein elevated the concentration of serum TC by 11% [（3.7±0.47, 4.1±0.61） mmol/L （Z=-2.668, P〈0.01）] on thelastday, whereas the concentration of serum TC increased by only 6% in soybean protein group （P 〉 0.05）. （2） The fecal excretions of calcium, phosphorus, magnesium, lipids and bile acids in subjects from both groups during the experiment： Compared with those in casein group, fecal excretions of calcium, phosphorus and magnesium of the subjects from soybean protein group were elevated by 60.3%, 44.1% and 55.0% （P 〈 0.05-0.01）; lipids and bile acids were 33.6% and 45.3%, respectively. （3） Correlation and regression analysis： The fecal bile acid excretion was positively correlated with fecal excretions of calcium, phosphorus, magnesium and lipids （t=3.173, 3.448, 2.411, 2.122, P 〈 0.05） for individual subject. CONCLUSION： A possible pathway of soybean protein＇s lowering serum cholesterol in humans is through enhancing fecal excretions of calcium, phosphorus, magnesium and bile acids.