Effect of bile fistulae on vitamin B12 absorption in rats

To study the effect of bile on the absorption of vitamin B12, choledochocolic fistulae were made in 26 rats, and 14 rats were sham-operated. Vitamin B12 absorption 9 days after the operation was significantly reduced in the fistula-operated group (median, 36.4%; range, 8.3-61.4%) as compared with the sham-operated group (median, 48.5; range, 35.8-75.2). Bile instilled together with vitamin B12 did not increase the absorption. In a second 'short-term' experiment external bile fistulae were made in 20 rats, and 10 rats were sham-operated. Vitamin B12 absorption was measured 14 h after the operation, and in this experiment no reduction was found in the fistula-operated rats. This suggests that bile in the lumen of the small intestine has no direct effect on vitamin B12 absorption, but absence of bile during several days may alter other factors of importance for the absorption.