A surface-reacted calcium carbonate comprising a calcium carbonate-comprising material, and at least one water-insoluble calcium salt selected from tricalcium phosphate and/or apatitic calcium phosphate, preferably selected from the group consisting of hydroxylapatite, substituted hydroxylapatite, octacalcium phosphate, and mixtures thereof, more preferably selected from the group consisting of hydroxylapatite, fluoroapatite, carboxyapatite, and mixtures thereof, and most preferably hydroxylapatite, wherein the surface-reacted calcium carbonate comprises (i) a specific surface area of from 20 to 200 m 2 /g measured using nitrogen and the BET method according to ISO 9277:2010; (ii) an intra-particle intruded specific pore volume in the range of from 0.1 to 2.3 cm 3 /g calculated from mercury porosimetry measurement, and/or an intra-particle pore size in a range of from 0.004 to 1.0 μm, determined from mercury porosity measurement, and (iii) whitlockite in an amount of at least 0.1 wt.-%, based on the total amount of the calcium carbonate and the at least one water-insoluble calcium salt, preferably in an amount of at least at least 0.5 wt.-%, more preferably in an amount of at least 1 wt.-%, and most preferably in an amount of at least 2 wt.-%. a calcium carbonate-comprising material, and at least one water-insoluble calcium salt selected from tricalcium phosphate and/or apatitic calcium phosphate, preferably selected from the group consisting of hydroxylapatite, substituted hydroxylapatite, octacalcium phosphate, and mixtures thereof, more preferably selected from the group consisting of hydroxylapatite, fluoroapatite, carboxyapatite, and mixtures thereof, and most preferably hydroxylapatite, wherein the surface-reacted calcium carbonate comprises (i) a specific surface area of from 20 to 200 m 2 /g measured using nitrogen and the BET method according to ISO 9277:2010; (ii) an intra-particle intruded specific pore volume in the range of from 0.1 to 2.3 cm 3 /g calculated from mercury porosimetry measurement, and/or an intra-particle pore size in a range of from 0.004 to 1.0 μm, determined from mercury porosity measurement, and (iii) whitlockite in an amount of at least 0.1 wt.-%, based on the total amount of the calcium carbonate and the at least one water-insoluble calcium salt, preferably in an amount of at least at least 0.5 wt.-%, more preferably in an amount of at least 1 wt.-%, and most preferably in an amount of at least 2 wt.-%. (i) a specific surface area of from 20 to 200 m 2 /g measured using nitrogen and the BET method according to ISO 9277:2010; (ii) an intra-particle intruded specific pore volume in the range of from 0.1 to 2.3 cm 3 /g calculated from mercury porosimetry measurement, and/or an intra-particle pore size in a range of from 0.004 to 1.0 μm, determined from mercury porosity measurement, and to 2.3 cm 3 /g calculated from mercury porosimetry measurement, and/or an intra-particle pore size in a range of from 0.004 to 1.0 μm, determined from mercury porosity measurement, and (iii) whitlockite in an amount of at least 0.1 wt.-%, based on the total amount of the calcium carbonate and the at least one water-insoluble calcium salt, preferably in an amount of at least at least 0.5 wt.-%, more preferably in an amount of at least 1 wt.-%, and most preferably in an amount of at least 2 wt.-%.