The effect of long-term fibre and starch intake by man on faecal bile acid excretion.

Parameters of bile acid metabolism were studied in two populations with different dietary fibre and starch intake over a period of at least 5 years. Subjects with a high fibre and starch intake have significant increases in faecal wet weight (288.5 g day-1 vs. 136.1), faecal dry weight (39.3 g day-1 vs. 20.2), faecal bile acid excretion (393.0 mg day-1 vs. 115.4) and faecal bile acid:faecal dry weight ratio (13.6 vs. 5.8). There was no difference in bowel transit time measured with 3H-PEG 4000 as marker of the liquid phase. The cumulative 14CO2 excretion during the bile acid breath test was higher in the high-fibre group, compared with the low-fibre group (4.6% dose cumulative at 8 h vs. 2.5%). Serum triglyceride and cholesterol levels were comparable in both groups. It is suggested that increased faecal weight and bile acid secretion is due to the synergic effect of high fibre and starch intake upon colonic bacterial proliferation.