Binding of bile acids by dietary fiber

Binding of bile salts to food residue was studied in vitro and in vivo. In the in vitro experiments, residues of a number of foods were incubated with each of several bile salts at different concentrations and pHs. All food residues tested adsorbed more dihydroxy than trihydroxy bile salts. Bile salt binding increased as bile salt concentration increased and was greater at a low pH. The extent of bile salt adsorption to some food residues could be clinically important. In patients with short ileal resections, we compared the rates of fecal excretion of labelled cholic and chenodeoxycholic acids and of a nonabsorable marker during ingestion of an ordinary diet (approximately 5 g of fiber) and a residue-free liquid diet. Coefficients of bile salt adsorption were calculated. Both bile acids were absorbed more efficiently during the liquid diet. Chenodeoxycholic acid was preferentially bound to the particulate matter of stools of patients eating the fiber-containing diet. It seems possible that dietary fiber could affect the enterohepatic circulation of bile salts in certain patients with ileal resection.