Effects of lactitol-oligosaccharides on calcium and magnesium absorption in rats

Lactitol-oligosaccharide (LO) was prepared from lactitol by transglycosylation reaction with Aspergillus oryzae beta-galactosidase. LO is resistant to metabolism in the small intestine but not in the large intestine. The effects of LO, lactose (Lac), lactitol (Lacol) and galactooligosaccharide (GL) on calcium and magnesium absorption were determined by feeding 8-week-old Sprague-Dawley male rats diets containing 5% of the above carbohydrates for two weeks. The results obtained were as follows. 1) A significant increase of calcium absorption was observed in the LO diet. 2) A significant increase of magnesium absorption was observed in the LO, GL and Lacol diets. 3) The concentration of total volatile fatty acids (VFA) in the cecal contents increased significantly in the LO, GL and Lacol diets. The main constituent of VFA in the cecal contents was found to be acetic acid. 4) The correlations between calcium and magnesium absorption ratios and total VFA concentration in the cecum were found to be significantly related. These findings suggest that LO is metabolized to VFA, among which acetic acid concentration seems to have the most stimulatory effect on the absorption of calcium.