RESUMO
The aim of the current study was to investigate the effect of an acidity regulator (SPORIX®), lactose, and vitamin D3 as excipient ingredients on digestive solubility and intestinal transport of calcium from four different calcium materials (tricalcium phosphate (TCP), fish bone (FB), nano-fish bone (NFB), and algae calcium (AC)) through an in vitro digestion model system combined with Caco-2 cells. The concentration of ionized calcium (Ca2+) in an aqueous fraction after in vitro digestion increased with the addition of SPORIX®, and it was further enhanced by adding SPORIX® + lactose + vitamin D3 into TCP, FB, NFB, and AC, respectively. In particular, FB with SPORIX® + lactose + vitamin D3 enhanced calcium ionization to 33.89 ± 0.69 mg g-1, which was about 11.76 times higher than that of FB only. In the case of intestinal cellular uptake of calcium, there was no significant difference in all the tested calcium materials with SPORIX® + lactose + vitamin D3. However, the absolute amount of intestinal transport of calcium in FB (43.95 ± 3.29 µg) was significantly higher than other calcium materials with the addition of SPORIX® + lactose + vitamin D3 (p < 0.05). This study suggests that the co-consumption of SPORIX®, lactose, and vitamin D3 with FB could enhance the calcium bioavailability by lowering pH as well as improving calcium intestinal transport by modulating the paracellular and transcellular uptake mechanism.