Fecal bile acid metabolic pattern after administration of different types of bread.

Increased concentrations of fecal bile acids have been suggested to be associated with increased risk of colorectal cancer. Fecal bile acid profiles were determined in 12 healthy Finnish women who included in their normal diets for 2-week periods in turn three different types of bread, 200-300 g/day. The breads contained either low-fiber wheat, whole-meal wheat, or whole-grain rye. During consumption of rye bread, the total mean concentration of fecal free bile acids was 4.77 +/- 0.90 mumol/g of dry feces (mean +/- SEM), which was much lower than with the normal omnivorous diet (8.05 +/- 1.56 mumol/g) or during administration of the low-fiber wheat bread (8.83 +/- 1.56 mumol/g) or the whole-meal wheat bread (7.88 +/- 1.34 mumol/g) (P less than 0.05). This decrease was mainly caused by increased proportions of saponifiable bile acids (P less than 0.01). During intake of the whole-grain rye bread, 46% +/- 3% of the fecal bile acids were in their saponifiable forms; this percentage was 30% +/- 3% during the control period, 30% +/- 4% during the low-fiber wheat bread period, and 27% +/- 4% during the whole-meal wheat bread period. It is concluded that the type of bread significantly effects concentrations of cocarcinogenic and comutagenic free lithocholic and deoxycholic acids by changing modes of conjugation in the gut.