Abstract

When the cholesterol saturation index of bile is reduced by wheat bran there is generally a fall in the deoxycholic acid content of bile. As the same effects occur with senna, bran might act on bile simply via its accelerating effect on colonic transit. We have studied the effects of a new, concentrated, wheat fibre preparation (Testa Triticum Tricum, Trifyba, which is 80% dietary fibre) upon bile composition, deoxycholic acid metabolism and intestinal transit time, and have assessed whether these effects are related. Twenty constipated volunteers were prescribed Testa Triticum Tricum in doses (10-32 g/day) sufficient to relieve their symptoms for at least six weeks. Before and at the end of this period, duodenal bile was sampled to enable measurement of deoxycholic acid pool (by isotope dilution), total bile acid pool, bile acid composition and cholesterol saturation index. Whole gut transit time fell from 120 +/- SD35 to 68 +/- 35 hours. At the same time, biliary % deoxycholic acid fell from 26.6 +/- 12.0 to 23.0 +/- 11.8 (p = 0.002), the total bile acid pool expanded from 2.36 +/- 0.88 to 2.75 +/- 0.90 g (p = 0.008) and cholesterol saturation index fell from 1.13 +/- 0.32 to 1.07 +/- 0.29 (p = 0.04). In subjects with initial cholesterol saturation index over 1.0 (n = 12), it fell from 1.33 +/- 0.25 to 1.22 +/- 0.21 (p = 0.008). There was no significant correlation between change in saturation index and change in % deoxycholic acid or deoxycholic acid pool, nor between any of these parameters and change in transit time. Testa Triticum Tricum reduces the cholesterol saturation index of supersaturated bile but this action appears to be independent of its effect on colonic transit and of changes in deoxycholic acid metabolism.