Embryonic egg white-derived peptides–calcium chelate enhances intestinal calcium transport: structural, digestive, and multi-omics insights

Enhancing calcium bioavailability through food-derived peptide-mineral complexes represents an important strategy for improving intestinal calcium absorption. This study converted peptides from day 9 embryonic egg white into a novel peptide–calcium chelate, EEWNPs-Ca. The results showed that calcium successfully coordinated with the functional groups of the EEWNPs (shifting the Fourier-transform infrared spectroscopy (FTIR) amide I band from 1632 to 1641 cm⁻¹), which transformed the amorphous lamellar matrix into highly crystalline spherical aggregates (novel X-ray diffraction (XRD) peaks at 28.32° and 40.54°). In addition, EEWNPs-Ca exhibited sustained calcium release, especially in the intestinal phase. Using a Caco-2 cell monolayer model, EEWNPs-Ca significantly enhanced calcium transport compared with CaCl₂ (6.33 μg vs. 5.09 μg, P < 0.05). Transcriptomic and metabolomic analyses revealed that EEWNPs-Ca broadly activated the cellular energy metabolism pathways (e.g., oxidative phosphorylation) and increased intracellular adenosine triphosphate (ATP) and amino acid levels, creating a favorable microenvironment for calcium absorption. Western blot analysis further verified that EEWNPs-Ca upregulated the expression of TRPV6, calbindin-D9k, and PMCA1b more effectively than CaCl₂. Collectively, while these in vitro findings provide promising mechanistic insights into the design of food-derived peptide-mineral complexes, further in vivo validation is required to confirm their physiological efficacy.