Comparison of the effects of milk components and calcium source on calciumbioavailability in growing male rats

We compared the effects of milk components (lactose and milk protein) and c alcium source on calcium bioavailability in growing male rats. Six-week-old male Sprague-Dawley rats were divided into four groups (Milk components (M C)+CaCO3, CaCO3, MC+WheyCa and WheyCa). Each group of rats was fed either a diet containing milk components plus CaCO3 or whey Ca, or a;;;ilk componen ts-free diet containing CaCO3 or whey Ca for 46 days. Calcium bioavailabili ty was defined by apparent calcium absorption rate and bone mine;all densit y (BMD). Two-way ANOVA was used to estimate the effects of milk components and calcium source on calcium bioavailability. The apparent calcium absorpt ion rate was estimated at 7 and 12 weeks of age. The type of dietary calciu m source did not affect the calcium absorption rate in either period. Howev er, the milk components significantly increased the apparent calcium absorp tion rate at 7 weeks of age, and tended to increase the apparent calcium ab sorption rate at 12 weeks of age (p=0.09). Moreover, the milk components in creased the apparent magnesium absorption rate in both periods. The type of dietary calcium source did not affect the BMD of the femur or lumbar verte brae (L3-L5). However, the milk components diet increased the BMD of femur and L3-L5. These data indicate that the administration of milk components i s more effective for the enhancement of calcium bioavailability rather than the chemical form of calcium in growing rats. (C) 1999 Elsevier Science In c.