An in vitro study to assess bioaccessibility and bioavailability of calcium from blue whiting (Micromesistius poutassou) fish bone powder

The aim of this study was to determine how well calcium-rich mineral extracts derived from blue whiting fish bone powders compare with existing calcium sources (commercially available fish bone supplement, calcium carbonate and milk powder) in terms of physicochemical properties, in vitro bioaccessibility and bioavailability using simulated gastrointestinal tract treatment and a Caco-2 cell culture model. Blue whiting calcium-rich fish bone powders (A to E) were supplied by Bio-marine Ingredients Ireland (BII) and a commercial calcium-rich fish bone powder was used as the positive control F. The BII calcium-rich fish bone powders analysed through atomic emission spectrometry were shown to have similar levels of mineral content in comparison with powder F. Solubility and rheology tests were performed on the rehydrated powders. The pH of BII calcium-rich fish bone powders in water solution (10% w/v) ranged from 6.96 to 9.09 compared to control F (pH 7.33). Following simulated oral, gastric and duodenal in vitro digestion using the COST INFOGEST standardised static adult digestion method, the fish powders A, E and F showed higher values of soluble ionic calcium than rehydrated milk powder. We compared in vitro bioavailability of the powders using the Caco-2 cell line to test the effects of calcium on human colonic epithelial cells, which confirmed that calcium from blue whiting fish bone was more bioavailable than calcium from milk and calcium carbonate. These data indicate that calcium-rich blue whiting fish bone powder compares well with existing calcium sources, in terms of physicochemical properties, bioaccessibility and bioavailability.