Calcium bioaccessibility and uptake by human intestinal like cells following in vitro digestion of casein phosphopeptide-calcium aggregates

• Published in: Food & function 2015-06, Vol.6 (6), p.1796-187
• Main Authors: Perego, Silvia, Del Favero, Elena, De Luca, Paola, Dal Piaz, Fabrizio, Fiorilli, Amelia, Cantu', Laura, Ferraretto, Anita
• Format: Article
• Language: English
• Subjects: Absorption, Physiological; Animals; Caco-2 Cells; Calcium, Dietary - metabolism; Caseins - chemistry; Caseins - metabolism; Dietary Supplements; Digestion; Enterocytes - metabolism; HT29 Cells; Humans; Hydrogen-Ion Concentration; Intestinal Absorption; Microscopy, Video; Molecular Weight; Nutritive Value; Particle Size; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Protein Hydrolysates - chemistry; Protein Hydrolysates - metabolism; Single-Cell Analysis; Up-Regulation
• ISSN: 2042-6496; 2042-650X
• DOI: 10.1039/c4fo00672k

Casein phosphopeptides (CPPs), derived by casein proteolysis, can bind calcium ions and keep them in solution. In vitro studies have demonstrated CPP-induced cell calcium uptake, depending on the formation of (CPP + calcium) complexes and on the degree of differentiation of the intestinal cells. With the present study, we address the persistence of the complexes and of the CPP-induced calcium uptake in intestinal like cells after the digestion process, thus examining their eligibility to serve as nutraceuticals. A calcium-preloaded CPP preparation of commercial origin (Ca-CPPs) was subjected to in vitro digestion. The evolution of the supramolecular structure of the Ca-CPP complexes was studied using laser-light and X-ray scattering. The bioactivity of the pre- and post-digestion Ca-CPPs was determined in differentiated Caco2 and HT-29 cells by video imaging experiments using Fura-2. We found that Ca-CPP aggregates keep a complex supramolecular organization upon digestion, despite getting smaller in size and increasing internal calcium dispersion. Concomitantly and most interestingly, digested Ca-CPPs clearly enhance the uptake of calcium ions, especially in Caco2 cells. In contrast, digestion depletes the ability of post-loaded decalcified-CPPs (Ca-dekCPPs), with a weaker internal structure, to induce calcium uptake. The enhanced bioactivity reached upon digestion strongly suggests a recognized role of Ca-CPPs, in the form used here, as nutraceuticals. Digestion optimizes calcium distribution within CPP vectors and improves their bioactivity.