Egg Chalaza Improves Calcium Utilization in Growing Rats: Evidence from Intestinal Aspects

Chalaza (CLZ), a byproduct generated during egg processing, has shown potential to promote calcium absorption, but its underlying mechanisms remain unclear. In a low-calcium growing rat model, coadministration of CLZ with CaCO3 dose-dependently increased apparent calcium absorption and retention, enhanced bone calcium deposition, and improved bone microarchitecture and mechanical properties compared with CaCO3 alone. These effects were accompanied by improved duodenal morphology, upregulation of intestinal calcium transport-related proteins (TRPV6, PMCA1b, and S100G/CaBP-D9k), and associated gut microbiota and SCFA changes. Representative digestion-derived peptides were synthesized and showed calcium-chelating capacity, inhibition of calcium phosphate crystallization, gastrointestinal calcium release, and thermal stability, supporting their role as exploratory calcium-binding candidates. Overall, this study supports the potential application of the high-value utilization of egg byproducts and the development of efficient calcium supplementation strategies.