Cohen L A, Kendall M E, Zang E, Meschter C, Rose D P
Division of Nutrition and Endocrinology, American Health Foundation, Valhalla, NY 10595.
J Natl Cancer Inst. 1991 Apr 3;83(7):496-501. doi: 10.1093/jnci/83.7.496.
A test of the anticancer effects of dietary fiber was conducted using the N-nitrosomethylurea (NMU)-induced rat mammary tumor model. Starting 3 days after NMU treatment, four different groups of F344 rats (30 rats in each group) were fed as follows: Group 1 received a high-fat diet; group 2, a high-fat plus fiber diet (soft white wheat bran, 10% wt/wt); group 3, a low-fat diet; and group 4, a low-fat plus fiber diet. The rats remained on these diets for 15 weeks. Tumor incidence in group 1 was 90% compared with 66% in group 2 (P less than .001). Tumor incidence in group 3 was 63% compared with 47% in group 4 (P greater than .4). These results show that supplemental dietary fiber exerts an inhibitory effect on the promotional phase of NMU-induced mammary carcinogenesis in rats when fed a high-fat but not a low-fat diet. To test whether fiber may exert its antipromoting effect by reducing circulating estrogens, serum 17 beta-estradiol was assayed. No changes were observed in serum 17 beta-estradiol levels among the four groups, suggesting that the protective effect of fiber in this animal model is not mediated by a fiber-induced reduction of circulating 17 beta-estradiol.
利用N-亚硝基甲基脲（NMU）诱导的大鼠乳腺肿瘤模型，对膳食纤维的抗癌作用进行了一项试验。在NMU治疗后3天开始，将四组不同的F344大鼠（每组30只）按以下方式喂养：第1组给予高脂饮食；第2组给予高脂加纤维饮食（软白麦麸，10%重量/重量）；第3组给予低脂饮食；第4组给予低脂加纤维饮食。这些大鼠持续食用这些饮食15周。第1组的肿瘤发生率为90%，而第2组为66%（P小于0.001）。第3组的肿瘤发生率为63%，而第4组为47%（P大于0.4）。这些结果表明，当给予高脂饮食而非低脂饮食时，补充膳食纤维对NMU诱导的大鼠乳腺致癌作用的促进阶段具有抑制作用。为了测试纤维是否可能通过降低循环雌激素发挥其抗促进作用，对血清17β-雌二醇进行了检测。四组之间血清17β-雌二醇水平未观察到变化，表明在该动物模型中纤维的保护作用不是由纤维诱导的循环17β-雌二醇减少介导的。
