Effect of ageing on postprandial conjugated and unconjugated serum bile acid levels in healthy subjects.

Colorectal cancer is a disease of elderly subjects. A decreased ileal absorption of bile acids in elderly subjects may lead to an increased exposure of the colonic mucosa to secondary bile acids. This may contribute to an enhanced risk of colorectal cancer. In this study fasting and postprandial conjugated and unconjugated serum levels of cholic, chenodeoxycholic, and deoxycholic acid in 12 elderly and 12 younger subjects were investigated. Intestinal transit time, gallbladder emptying and jejunal bacterial flora were also studied in both age groups. Fasting levels of conjugated and unconjugated serum bile acids were similar in both age groups. Postprandial levels of all individual conjugated bile acids increased to a significantly higher extent in the younger subjects. Postprandial unconjugated serum bile acid levels did not differ significantly between both age groups, although unconjugated deoxycholic levels tended to increase to higher levels in the elderly. Results of jejunal bacterial counts, gallbladder emptying and intestinal transit time were similar in both groups. These data suggest that conjugated bile acids are reabsorbed less effectively in elderly subjects.