Abstract
The effect of coexisting lactose and milk protein on the calcium (Ca) bioavailability of Ca carbonate was compared with that of a skim milk diet and a milk component-free diet containing Ca carbonate. Six-week-old male rats were divided into four groups: those given a skim milk powder diet (SM group), a skim milk powder diet in which half of the Ca was replaced with Ca carbonate (SM+CaCO3 group), a Ca carbonate diet with added milk components (MC+CaCO3 group), and without milk components (CaCO3 group), respectively. Rats were fed on each experimental diet for 46 days. No significant differences in food efficiency and body weight gain were found among the four groups. On the other hand, apparent Ca absorption at 7 weeks of age and femoral bone mineral densities (BMD) in the SM, SM+CaCO3 and MC+CaCO3 groups were higher than those in the CaCO3 group. The apparent Ca absorption rate and BMD were almost the same among the experimental groups receiving diets containing milk components (SM, SM+CaCO3 and MC+CaCO3 groups). These results suggest that the administration of lactose and milk protein is as effective on the Ca availability of Ca carbonate as that of Ca in skim milk powder.
