膳食纖維對小鼠腸道生理及血脂質之影響

本實驗主要目的在探討餵食不同膳食纖維對BALB/C 雄鼠之腸道生理、血脂、腸道短鏈脂肪酸濃度的影響。將約七周齡之小鼠隨機分配，每組8隻，分別餵食不含纖維（Fiber free；FF）測試纖維之AIN-93無纖維半純化飼料三週，測試纖維為纖維素（C）、蒟蒻（K）、及利用酸水解製備的三種蒟蒻水解產物 Fraction1、2及3（F1、2及3）、菊糖Inulin (I)、果寡醣Fructooligosaccharide (FO)共八組。蒟蒻水解產物F1、F2、及F3之平均聚合度 (degree of polymerization)分別為16、 10及4。於犧牲前連續收集小鼠糞便三天，利用氣相層析儀分析短鏈脂肪酸濃度。小鼠犧牲後取其血液、器官，測定其血脂濃度及腸道生理情形。 結果顯示，各組間的食物攝取量、體重及食物效應並無顯著差異；血脂濃度方面，F1及F 2降低總膽固醇、低密度脂蛋白膽固醇、低密度脂蛋白膽固醇/高密度脂蛋白膽固醇比值及三酸甘油脂之效果皆顯著優於蒟蒻及F3； I和FO組降低總膽固醇、低密度脂蛋白膽固醇、低密度脂蛋白膽固醇/高密度脂蛋白膽固醇比值及三酸甘油脂之效果皆顯著優於FF、C組。 不論餵食任何一種膳食纖維對增加新鮮糞便重量來說皆比FF組高；新鮮糞便重及水分方面，和FF組比較FO組有增加情形；短鏈脂肪酸濃度方面，F1提高盲腸內容物及新鮮糞便的乙酸、丙酸、正丁酸、異丁酸濃度之效果皆優於C、K、F2、F3、I、FO組。觀察腸道黏膜表皮細胞形態結果顯示，小鼠胃、盲腸、大腸部位：FO組之絨毛高度、Labeled villous height (μm)、 Labeled zone (%)、Labeled cell number、Total cell number、Labeled cell density (%)、絨毛面積 (μm2)絨毛增生指標皆最高。 因此，平均聚合度為10-16之蒟蒻葡甘露聚醣對降低血脂之效果優於高分子蒟蒻及平均聚合度為4之蒟蒻寡醣；而平均聚合度為16之蒟蒻葡甘露聚醣促進腸道發酵產物之效果最佳。平均聚合度為2之果寡醣對胃、盲腸、大腸的絨毛增生具有最佳效果。

This study investigated the effects of different dietary fiber on upper gut function, serum lipid and the concentrations of short chain fatty acids in the cecal content and feces in adult BALB/C mice. Mice were randomly allocated to consume one of eight for 21 days, diets including the fiber free, AIN-modified 5% fiber diet. Fiber sources were cellulose, konjac, and three kinds of hydrolysate of Konjac (Fraction 1,2,3),Inulin and Fructooligosaccharide (FO）. The average polymerization degree of fraction 1, 2 and 3 were 16, 10 and 4, respectively we collected the fecal of the mice for serial three days before killing them, after that we used gas chromatography to analyze the concentration of sort chain fatty acid. After sacrificing, we used the blood and organs to analyze the concentration of serum lipid and their physiology of gut. The results indicated that there was no significant in food intake, body weight, and food efficiency between these groups. F1 and F2 significantly (p＜0.05) reduced total plasma cholesterol, LDL-cholesterol、LDL-cholesterol /HDL-cholesterol and Triglyceride comparing to Konjac and F3; Besides, the groups, fed Inulin and Fructooligosaccharide, significantly (p＜0.05) reduced total cholesterol, LDL-cholesterol, LDL-cholesterol / HDL-cholesterol, Triglyceride comparing to FF and C group. Except feeding Fiber Free, feeding the other seven kinds of fiber diets can increase the fresh fecal weight. Fructooligosaccharide is higher than the other groups in fresh fecal weight and moisture. In the concentration of the sort chain fatty acid, the group fed F1 was significantly increased. And the contents in the cecum and the effects of acetic acid, propionic acid, n-butyric acid and i-butyric acid in the fresh fecal were higher than Cellulose, Konjac, F2, F3,Inulin, and Fructooligosaccharide. After observing the epidermic cell of gut mucosa on gastric, cecum and large intestine, the group of feeding Fructooligosaccharide had proliferative the highest index in villous height, villous width, Labeled villous height, Labeled zone, Labeled cell number, Total cell number, Labeled cell density, Area of all groups. In summary, glucomannan, the average degree of polymerization which was between 16-10, had better effects on reducing the concentration of serum lipid than high molecular weight Konjac and the oligosaccharide. The average degree of polymerization was 4. Besides, glucomannan, the average degree of polymerization was 16, which had the best effect on promoting the fermentative product in gut, and glucomannan that the average degree of polymerization was 2, which had the best effect on villous proliferation in gastric, cecum, and large intestine.