Rats fed high starch diets have lower colonic proliferation and fecal bile acids than high sucrose-fed controls

We studied the effects of sucrose or starch in the diet (460 g/kg diet) on fecal bile acid concentrations in Sprague Dawley rats after 4 wk of feeding. Total bile acid concentration in the feces was significantly lower in the rats fed the starch diet than in those fed the sucrose diet (4.56 +/- 0.47 mg/g dry weight and 8.03 +/- 0.94, respectively, SEM), due to a reduction of deoxycholic, alpha-muricholic and beta-muricholic acids. Fecal and cecal pH values were significantly lower in the rats fed the starch diet compared to those fed the sucrose diet (6.79 +/- 0.08 and 7.15 +/- 0.09 for fecal pH and 7.02 +/- 0.05 and 7.2 +/- 0.04 for cecal pH in the two diet groups, respectively). Colon proliferation was also significantly lower in the starch-fed rats compared to those fed sucrose (labeling index 3.51 +/- 0.6 and 5.69 +/- 0.74, respectively), and the reduction was apparent in the middle and upper compartments of the colon crypts. The mucosal proliferation, expressed as percentage of labeled cells in the upper compartment of the colon crypts, was positively correlated with the concentration of deoxycholic, lithocholic, alpha-muricholic, beta-muricholic, cholic and total bile acids in the feces (per gram wet weight). The results indicate a protective effect of starch versus sucrose diets on colon mucosa.