Chitosan encapsulation soy peptide–calcium promotes calcium absorption and bone health of rats fed a low calcium diet

• Soy peptide–calcium was successfully encapsulated into the chitosan. • Particles exhibited a sustained release effect under simulated gastrointestinal digestion. • COS–SPs–Ca exhibited positive effects on calcium bioavailability, bone biomechanics and histomorphometry in rats. • COS–SPs–Ca upregulated mRNA expression levels of genes involved in calcium-promoting mechanisms in the small intestine. Calcium deficiency is considered widespread globally, and discovering calcium with high bioavailability is one of the keys to solving calcium deficiency. This study prepared a calcium delivery system with chitosan and soy peptide and investigated its characteristics, ability to promote calcium absorption, and effects on bone health. The experiment results reveal that chitosan encapsulates soybean peptide–calcium (COS–SPs–Ca) with carboxyl oxygen atoms, amino nitrogen atoms, and phosphate ions, which has a slow-release effect in simulated gastrointestinal digestion. In calcium-deficient rats, COS–SPs–Ca has beneficial effects on serum biochemical parameters, bone biomechanics, and bone microarchitecture, and significantly up-regulated the gene expression of TRPV5, TRPV6, PepT1, and Calbindin-D9k in the small intestine. These results suggest that COS–SPs–Ca is a promising calcium supplement.