Nagengast F M, van den Ban G, Ploemen J P, Leenen R, Zock P L, Katan M B, Hectors M P, de Haan A F, van Tongeren J H
Department of Medicine, University Hospital Nijmegen, The Netherlands.
Eur J Clin Nutr. 1993 Sep;47(9):631-9.
Dietary fibre possibly protects against colonic cancer by effects on bile acid metabolism. We investigated the effect of a natural high-fibre diet on secondary bile acid formation. Twelve healthy subjects on an habitual low-fibre diet (for 4 weeks) consumed a high-fibre menu for 10 weeks (experimental group). A control group of 10 subjects consumed their regular high-fibre diet during this period. Faecal and biliary acid composition, faecal weight, faecal pH and gut transit time were studied before and after 6 and 10 weeks of fibre addition. Changes in the experimental group were compared to changes in the control group. The concentration, but not the excretion, of the secondary faecal bile acids was reduced in the experimental group. Faecal weight increased, faecal pH dropped and gut transit time was not altered. The biliary deoxycholic acid content decreased and the cholic acid content increased after 6 weeks, but returned to baseline values after 10 weeks of fibre addition. This study shows that a natural high-fibre diet lowers secondary faecal bile acid concentration through an increase in stool weight. The 7 alpha-dehydroxylation of primary bile acids is probably not or only transiently inhibited.
膳食纤维可能通过对胆汁酸代谢的影响来预防结肠癌。我们研究了天然高纤维饮食对次级胆汁酸形成的影响。12名习惯低纤维饮食（持续4周）的健康受试者食用了10周的高纤维菜单（实验组）。在此期间，10名受试者组成的对照组食用其常规高纤维饮食。在添加纤维6周和10周前后，研究了粪便和胆汁酸组成、粪便重量、粪便pH值和肠道转运时间。将实验组的变化与对照组的变化进行比较。实验组中次级粪便胆汁酸的浓度降低，但排泄量未降低。粪便重量增加，粪便pH值下降，肠道转运时间未改变。添加纤维6周后，胆汁中脱氧胆酸含量降低，胆酸含量增加，但添加纤维10周后恢复到基线值。这项研究表明，天然高纤维饮食通过增加粪便重量降低次级粪便胆汁酸浓度。初级胆汁酸的7α-脱羟基作用可能不会受到抑制，或者只是暂时受到抑制。
