Brauer P M, Slavin J L, Marlett J A
Am J Clin Nutr. 1981 Jun;34(6):1061-70. doi: 10.1093/ajcn/34.6.1061.
These experiments assessed the ability of the neutral detergent fiber (NDF) method to remove starch and nitrogen from food NDF residues, and nitrogen and endogenous secretions from fecal NDF residues; and compared indices of bowel function, including apparent NDF digestibility, of nine elderly subjects to those of six young women. Subjects consumed similar, controlled "low fiber" diets containing foods typically eaten in the United States. Nitrogen and starch contents of food composite NDF were determined in NDF obtained by the hog alpha amylase modification of the Van Soest procedure, whereas the nitrogen content of fecal NDF was determined using NDF obtained by the unmodified procedure. The modified Van Soest method adequately removed nitrogen and starch from food NDF, but fecal NDF contained nitrogen. Both groups digested the majority of the NDF, 63 and 70% for the elderly and young subjects, respectively. Apparent fiber digestibility, which was measured several times in each subject, increased to 69 and 75% for the two groups, respectively, when a correction was made for the nitrogen in the fecal NDF. Mean gastrointestinal transit time and frequency of defecation of the two age groups were comparable, whereas mean daily wet and dry stool weights of the elderly were larger than those of the young women. These results suggest that the bowel of the elderly may function as well as that of the young adult.
这些实验评估了中性洗涤纤维（NDF）法从食物NDF残渣中去除淀粉和氮，以及从粪便NDF残渣中去除氮和内源性分泌物的能力；并比较了9名老年受试者和6名年轻女性的肠道功能指标，包括表观NDF消化率。受试者食用了类似的、经过控制的“低纤维”饮食，这些饮食包含美国常见的食物。食物复合NDF中的氮和淀粉含量是在通过对Van Soest方法进行猪α淀粉酶改良而获得的NDF中测定的，而粪便NDF中的氮含量是使用未经改良的方法获得的NDF来测定的。改良的Van Soest方法能充分从食物NDF中去除氮和淀粉，但粪便NDF中含有氮。两组受试者都消化了大部分的NDF，老年组和年轻组分别为63%和70%。在对每个受试者进行多次测量时，当对粪便NDF中的氮进行校正后，两组的表观纤维消化率分别提高到了69%和75%。两个年龄组的平均胃肠道转运时间和排便频率相当，而老年人的每日平均湿便和干便重量均大于年轻女性。这些结果表明，老年人的肠道功能可能与年轻成年人一样良好。
