Effect of lactose on calcium absorption from the rat small intestine with a non-flushed ligated loop.

To assess the effect of dietary lactose on the utilization of 40Ca and 45Ca, a one-day balance experiment was carried out. The urinary 45Ca excretion and 45Ca deposition in the femur were significantly higher in the 10% lactose diet group. In the second experiment, non-flushed lower small intestine was ligated in situ and calcium absorption was observed shortly after injecting lactose solution into the loop during the postprandial state. The estimated amounts of 40Ca and 45Ca absorbed and of 45Ca deposited in the femur were increased in the presence of lactose in the test solution. These results suggest that dietary lactose stimulates calcium utilization and also increases calcium absorption from the undisturbed small intestine containing digests.