Effect of lactose or its component sugars on jejunal calcium absorption in adult man.

The effect of lactose vs glucose plus galactose on jejunal calcium absorption was studied in 10 subjects using a triple-lumen perfusion technique. In each, 30 cm of jejunum was perfused with two test solutions. The comparisons made were lactose (Lac) vs mannitol (Man), Lac vs glucose and galactose (GG), and Man vs GG. Compared with Man, Lac, and GG caused a significant increase in net water and sodium absorption and luminal calcium concentration. In subjects receiving both Lac and GG, water and sodium absorption were greater with GG. The only statistically significant increase in net calcium absorption occurred with Man vs GG in which water absorption increased from 16 to 350 mL.h-1.30 cm-1. However, by use of data from all test solutions, water and sodium absorption were found to be significantly correlated with calcium absorption (p less than 0.05). These results suggest that lactose or its component sugars enhance jejunal calcium absorption in proportion to their effect on fluid absorption.