Solubility and bioavailability of stabilized amorphous calcium carbonate

Abstract

Since its role in the prevention of osteoporosis in humans was proven some 30 years ago, calcium bioavailability has been the subject of numerous scientific studies. Recent technology allowing the production of a stable amorphous calcium carbonate (ACC) now enables a bioavailability analysis of this unique form of calcium. This study thus compares the solubility and fractional absorption of ACC, ACC with chitosan (ACC-C), and crystalline calcium carbonate (CCC). Solubility was evaluated by dissolving these preparations in dilute phosphoric acid. The results demonstrated that both ACC and ACC-C are more soluble than CCC. Fractional absorption was evaluated by intrinsically labeling calcium carbonate preparations with 45 Ca, orally administrated to rats using gelatin capsules. Fractional absorption was determined by evaluating the percentage of the administrated radioactive dose per milliliter that was measured in the serum, calcium absorption in the femur, and whole-body retention over a 34-hour period. Calcium serum analysis revealed that calcium absorption from ACC and ACC-C preparations was up to 40% higher than from CCC, whereas retention of ACC and ACC-C was up to 26.5% higher than CCC. Absorbed calcium in the femurs of ACC-administrated rats was 30% higher than in CCC-treated animals, whereas 15% more calcium was absorbed following ACC-C treatment than following CCC treatment. This study demonstrates the enhanced solubility and bioavailability of ACC over CCC. The use of stable ACC as a highly bioavailable dietary source for calcium is proposed based on the findings of this study. ß

In situ molecular NMR picture of bioavailable calcium stabilized as amorphous CaCO3biomineral in crayfish gastroliths

“…For instance, ACC has been shown to serve as a transient form designed to spontaneously evolve into a preset specific crystalline form with sculptured morphology (9)(10)(11). It has also been shown that ACC can be stabilized to remain in a highly soluble amorphous state, in which case the calcium can be readily retrieved, thus establishing its bioavailability (12,13). These properties of ACC attract extensive scientific, technological, and biomedical interest.…”

Mineral CO2 sequestration by environmental biotechnological processes

“…CaCO 3 is known to occur in unstable and more stable polymorphs. The CaCO 3 polymorphs in decreasing stability are: calcite, aragonite, vaterite, monohydrocalcite, ikaite and amorphous calcium carbonate (Meiron et al, 2011;Radha et al, 2010). Although CaCO 3 deposition in anaerobic reactors is commonly occurring and therefore it has been extensively studied (Langerak et al, 1999;Lier & Boncz, 2002), its interconnections with silicate mineral dissolution and biogas improvement have not been studied.…”

Scientific Opinion on re‐evaluation of calcium carbonate (E 170) as a food additive

“…Five of these are crystalline and one is amorphous (hydrated amorphous calcium carbonate (Meiron et al, 2011). Of the five crystalline forms, three are anhydrous crystalline (i.e., calcite, aragonite, and vaterite) and two are hydrated crystalline (i.e., crystalline monohydrocalcite and ikaite) (Meiron et al, 2011). The most thermodynamically stable of these forms is calcite, whereas the least stable is the amorphous form (Nebel et al, 2008;Meiron et al, 2011).…”

“…Particles of amorphous calcium carbonate are reported to be characteristically 40 to 120 nm diameter spherules, in contrast to the 1 to 10 µm diameter crystals typical of the other forms (Meiron et al, 2011). According to the Calcium Carbonate Association (CCA-Europe) engineered nanoscale calcium carbonate is not used as a food additive.…”

“…The EU Scientific Committee for Food (SCF) evaluated calcium carbonate in 1990 as part of a group of carbonates (SCF, 1991), and a review of carbonates as food additives has been carried out by TemaNord (TemaNord, 2002 Calcium carbonate is an odourless white micro-crystalline or amorphous powder with six known forms (polymorphs). Five of these are crystalline and one is amorphous (hydrated amorphous calcium carbonate (Meiron et al, 2011). Of the five crystalline forms, three are anhydrous crystalline (i.e., calcite, aragonite, and vaterite) and two are hydrated crystalline (i.e., crystalline monohydrocalcite and ikaite) (Meiron et al, 2011).…”