The effect of a natural high-fibre diet on faecal and biliary bile acids, faecal pH and whole-gut transit time in man. A controlled study.
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.
Nagengast
F M
FM
Department of Medicine, University Hospital Nijmegen, The Netherlands.
van den Ban
G
G
Ploemen
J P
JP
Leenen
R
R
Zock
P L
PL
Katan
M B
MB
Hectors
M P
MP
de Haan
A F
AF
van Tongeren
J H
JH
D000328:Adult; D000368:Aged; D001647:Bile Acids and Salts / Q000032:analysis* / Q000737:chemistry*; D016022:Case-Control Studies; D019826:Cholic Acid; D002793:Cholic Acids / Q000032:analysis; D003110:Colonic Neoplasms / Q000178:diet therapy / Q000517:prevention & control; D003840:Deoxycholic Acid / Q000032:analysis; D004043:Dietary Fiber; D004734:Energy Metabolism; D005243:Feces / Q000737:chemistry*; D005772:Gastrointestinal Transit; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008875:Middle Aged; D015596:Nutrition Assessment; D013997:Time Factors
D001647:Bile Acids and Salts; D002793:Cholic Acids; D004043:Dietary Fiber; D003840:Deoxycholic Acid; D019826:Cholic Acid