大豆蛋白对人体血浆胆固醇的影响及机制探讨

目的观察大豆蛋白对正常人体血浆胆固醇浓度的影响并探讨其作用机制。方法选择健康大学生30名，男女各半，按血浆总胆固醇浓度、体重和性别均衡的原则，分为3组，在统一食谱、集中就餐的基础上，每天分别另外摄入30g酪蛋白，30g大豆分离蛋白，30g酪蛋白加880mg钙，共14d。实验开始和结束时．测量身高和体重：采血，测定血浆总胆固醇浓度。实验结束前，收集3d粪便，测定粪脂肪、钙、磷、镁和胆汁酸的排出量。结果(1)同实验开始时比，酪蛋白组血浆胆固醇浓度显著升高，而大豆蛋白组和酪蛋白加钙组血浆胆固醇浓度升高不明显。(2)同酪蛋白组比，大豆蛋白组粪钙、磷和镁的排出量均显著增加；粪脂肪和胆汁酸排出量分别增加33．6％和45．3％。(3)粪胆汁酸排出量与粪钙、磷、镁和脂肪的排出量呈显著性正相关。血浆胆固醇浓度随粪胆汁酸排出量增加呈下降的趋势。结论大豆蛋白降低血浆胆固醇浓度的机制可能是由于增加粪胆汁酸的排出量而导致肝脏中由胆固醇合成胆汁酸的增加，从而使血浆胆固醇浓度下降。

Effect of soybean protein on serum cholesterol in human and its possible mechanism

Objective To observe the effect of soybean protein on the concentration of serum cholesterol in human and to explore the possible mechanism.Methods Fifteen male and 15 female young health college students were divided into 3 groups based on the concentration of serum cholesterol,sex and body weight.Except the same basic diet for each meal,subjects ingested 30g casein or 30g soybean protein or 30g casein with 880mg calcium each day for 14 days,respectively.The body height and body weight were measured at the beginning and the end of the experiment.Blood samples were collected on the day beore and after the trial,and serum total cholesterol was examined.Feces samples were collected totally at the last 3 days of the experiment and the excretion of fecal lipids,calcium,phosphorus,magnesium,and bile acids were measured.Results (1)Compared with the beginning,the concentration of serum total cholesterol from casein group increased significantly at the end of the experiment.Whereas,the increase of serum total cholesterol from solybean protein group and casein with calcium group was insignificant.(2)Compared with casein group,excretions of fecal calcium,phosphorus and magnesium in soybean protein group were increased significantly,excretions of fecal lipids and bile acids were increased by 33.6% and 45.3%,respectively.(3)The fecal bile acid excretion correlated positively with the excretion of fecal calcium,phosphorus,magnesium and lipids.The concentration of serum total cholesterol trended to decrease as the excretion of fecal bile acid increased.Conclusion More excretion of fecal bile acid by intake of soybean protein may induced a low cancentration of serum total cholesterol via increase in the synthesis of bile acids from cholesterol in liver.