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

Abstract

We compared the effects of milk components (lactose and milk protein) and calcium source on calcium bioavailability in growing male rats. Six-week-old male Sprague-Dawley rats were divided into four groups (Milk components (MC)+CaCO 3, CaCO 3, MC+WheyCa and WheyCa). Each group of rats was fed either a diet containing milk components plus CaCO 3 or whey Ca, or a milk components-free diet containing CaCO 3 or whey Ca for 46 days. Calcium bioavailability was defined by apparent calcium absorption rate and bone mineral density (BMD). Two-way ANOVA was used to estimate the effects of milk components and calcium source on calcium bioavailability. The apparent calcium absorption rate was estimated at 7 and 12 weeks of age. The type of dietary calcium source did not affect the calcium absorption rate in either period. However, the milk components significantly increased the apparent calcium absorption rate at 7 weeks of age, and tended to increase the apparent calcium absorption rate at 12 weeks of age (p=0.09). Moreover, the milk components increased the apparent magnesium absorption rate in both periods. The type of dietary calcium source did not affect the BMD of the femur or lumbar vertebrae (L3–L5). However, the milk components diet increased the BMD of femur and L3–L5. These data indicate that the administration of milk components is more effective for the enhancement of calcium bioavailability rather than the chemical form of calcium in growing rats.