McPherson-Kay R
Prev Med. 1987 Jul;16(4):540-4. doi: 10.1016/0091-7435(87)90069-7.
Dietary fiber has direct effects on stool bulk and bile acid output that may be of relevance in the etiology of colon cancer. Most types of fiber increase the total volume of stool and reduce the concentration of specific substances, including bile acids, that are in contact with the bowel wall. However, fibers differ in their effect on stool bulk, with wheat fiber being a more effective stool bulking agent than fruit and vegetable fibers. In addition, the extent to which a specific fiber reduces bile acid concentration will be modified by its concomitant effects on total fecal sterol excretion. Whereas wheat bran reduces fecal bile acid concentration, pectin, lignin, and oat bran do not. These three fibers significantly increase total bile acid output. Bile acids act as promoters of colonic tumors in mutagenesis assay systems and in various animal models. Human epidemiological studies show a relationship between various dietary variables, including fat and fiber intake, fecal concentration of bile acids, and colon cancer risk.
膳食纤维对粪便量和胆汁酸排出有直接影响，这可能与结肠癌的病因学相关。大多数类型的纤维会增加粪便总体积，并降低与肠壁接触的特定物质（包括胆汁酸）的浓度。然而，不同纤维对粪便量的影响存在差异，小麦纤维比水果和蔬菜纤维更能有效增加粪便量。此外，特定纤维降低胆汁酸浓度的程度会因其对粪便总固醇排泄的伴随影响而改变。麦麸可降低粪便胆汁酸浓度，而果胶、木质素和燕麦麸则不然。这三种纤维会显著增加胆汁酸的总排出量。在诱变分析系统和各种动物模型中，胆汁酸可作为结肠肿瘤的促进剂。人类流行病学研究表明，包括脂肪和纤维摄入量、粪便胆汁酸浓度以及结肠癌风险在内的各种饮食变量之间存在关联。
