Yu C F, Whiteley L, Carryl O, Basson M D
Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Dig Dis Sci. 2001 Jul;46(7):1367-80. doi: 10.1023/a:1010615215528.
The effects of fiber on colon cancer are controversial. Twenty 5-week old C57BL/6J Apc Min/+ mice were fed for 60 days with a commercial mouse diet (Teklad LM-485) and eight semidefined diets containing 5-10% various fibers and 20% soybean oil. Ten additional C57BL/6J congenic litter-mates were fed each diet to assay colonic SCFA. SCFA, stool bulk, and colonic tumor incidence differed only slightly among the semidefined diets despite variations in fiber content and source. However, food consumption, caloric intake, stool bulk, and SCFA were substantially increased by the Teklad diet compared with all other groups. The Teklad diet significantly increased the number of mice with colonic tumors, average number of tumors/mouse, total tumor burden, colonic atypical hyperplasia, and small bowel tumors. Mice fed high-fat, no-fiber diets had more small bowel tumors (29.8 +/- 3.1) than mice fed diets with fiber (8.2 +/- 2.1) or with low fat and no fiber (18.1 +/- 3.4) (P < 0.05 for each group). These studies suggest that fat predisposes to and fiber protects against small bowel tumors but not colon tumors in these mice. Thus, diets high in fiber or yielding high colonic luminal SCFA may not necessarily protect against colonic cancer. Furthermore, the effects of dietary fiber in Teklad appear overshadowed by some other biologically active factors in this animal model.
膳食纤维对结肠癌的影响存在争议。将20只5周龄的C57BL/6J Apc Min/+小鼠用市售小鼠饲料（Teklad LM-485）以及八种含5%-10%不同纤维和20%大豆油的半精制饲料喂养60天。另外每组用10只C57BL/6J同基因同窝仔鼠喂食每种饲料，以测定结肠短链脂肪酸（SCFA）。尽管纤维含量和来源有所不同，但在半精制饲料中，SCFA、粪便量和结肠肿瘤发生率仅有轻微差异。然而，与所有其他组相比，Teklad饲料显著增加了食物消耗量、热量摄入量、粪便量和SCFA。Teklad饲料显著增加了患有结肠肿瘤的小鼠数量、每只小鼠的平均肿瘤数量、总肿瘤负荷、结肠非典型增生和小肠肿瘤。喂食高脂肪无纤维饲料的小鼠比喂食含纤维饲料（8.2±2.1）或低脂无纤维饲料（18.1±3.4）的小鼠有更多的小肠肿瘤（29.8±3.1）（每组P<0.05）。这些研究表明，在这些小鼠中，脂肪易引发小肠肿瘤，而纤维可预防小肠肿瘤，但对结肠肿瘤无效。因此，高纤维饮食或产生高结肠腔内SCFA的饮食不一定能预防结肠癌。此外，在这个动物模型中，Teklad饲料中的膳食纤维的作用似乎被其他一些生物活性因素所掩盖。
