Effects of a fat-reduced diet on the faecal excretion of radioactivity following administration of 14C-cholic acid and on the duodenal concentration of bile salts in patients with ileal disease.

The fraction of faecal radioactivity excreted after intravenous administration of 14C-labelled cholic acid decreased in most patients with ileopathy and bile salt malabsorption when the dietary daily fat content was reduced from 100 to 40 g. The decreased faecal cholic acid loss might be due to increased bile salt absorption and decreased emptying of the gall-bladder on the fat-reduced diet. A simplified method to determine the corrected 24-hour excretion of radiologically labelled bile salts is described.