Calcium from LactoCalcium(TM) milk mineral after digestion with pepsin stimulates mineralized bone nodule formation in human osteoblast-like SaOS-2 cells in vitro and may be rendered bioavailable in vivo

Many individuals cannot obtain the optimum calcium requirement from food for a variety of reasons. Therefore, calcium supplements are important sources of dietary calcium. One of the calcium sources commercially available is LactoCalciumsup(TM)(milk minerals) that has 28 % calcium, and a 2:1 ratio of calcium to phosphorus. The objectives of this study were (a) to examine whether calcium can be released from LactoCalciumsup(TM) by using digestive enzymes and (b) to determine its biological activity by examining its ability to stimulate bone formation. LactoCalciumsup(TM) was treated in vitro by using simulated gastric and intestinal fluids or porcine gastric, pancreatic and intestinal extracts. Our results indicate the role of enzymes or bile extract in the digestion of the product. We show that, by increasing the concentration of pepsin at a fixed concentration of LactoCalciumsup(TM) (substrate), the percentage of released calcium increased in a dose-dependent manner, showing that, at the right enzyme concentration, as much as 100% of the calcium present in LactoCalciumsup(TM) can be made available. The biological activity of the digested calcium was demonstrated by the stimulation of mineralized bone nodules in SaOS-2 cells in a dose-dependent manner. Thus, 1 mM and 3 mM calcium released from LactoCalciumsup(TM) increased the nodule area by 23.17 square mm (p0.0001) and 77.78 square mm (p0.0001), respectively, as compared to a value of 0.99 square mm at 0.5 mM calcium from LactoCalciumsup(TM). These results demonstrate the in vitro bioavailability and bioactivity of calcium from LactoCalciumsup(TM) and serve as a basis for carrying out in vivo analyses to determine the suitability of using LactoCalciumsup(TM) as a source of calcium for individuals at risk of developing osteoporosis.