The absorption of bile acids from the human large bowel was studied in eight patients. All patients had cholecystitis and cholelithiasis and had to undergo cholecystectomy. Cholic acid-14C was injected during surgery into the lumen of the cecum, hepatic flexure of the colon, or transverse colon in six patients, under the visual control of the surgeon. Common duct bile was collected by T tube daily for 5 days, and bile acids were extracted. Significant amounts of radioactivity appeared in T tube bile in each patient. T tube bile acids contained a total of 43.6-84.6% of the administered radioactivity; the average for the six patients was 58.9%. The majority of the tracer was excreted during the first 24 hr. In an additional patient cholic acid-14C was given in the form of an enema 5 days postoperatively. In this subject 30.8% of the retained radioactivity was excreted through the T-tube in 48 hr. The labeled cholic acid was recovered as both cholic and deoxycholic acid from T tube bile. Thin-layer chromatographic analysis of the bile acid samples indicated that the fraction of radioactivity recovered as deoxycholate increased with time during the postoperative period. Gas-liquid chromatographic analysis showed that the daily total quantity of excreted bile acids increased significantly from the 1st-5th days of the experiment. The amount of cholate excreted in T tube bile increased markedly with time, that of chenodeoxycholate increased moderately, and that of deoxycholate decreased sharply during the 5 days of the experiment. In three patients, injection of radiopaque material mixed with the tracer showed no evidence of regurgitation into the small bowel by serial X-rays. In an additional patient, tube aspirate from the terminal ileum contained no radioactivity. The results indicate that cholic acid is converted to deoxycholic acid in the human colon, and both of these bile acids are absorbed from the human large bowel in significant amounts. These data establish the previously unproved concept that significant absorption of bile acids takes place from the large bowel of man.
Paul Samuel, George M. Saypol, Edward Meilman, Erwin H. Mosbach, Mohsen Chafizadeh