Potential dietary calcium supplement: Calcium-chelating peptides and peptide-calcium complexes derived from blue food proteins

Nutritional calcium is necessary for constituting human tissues and maintaining normal physiological functions. Calcium deficiency is easy to cause many nutritional deficiency diseases. Calcium-chelating peptide is a kind of peptide that can improve the bioavailability of calcium. Blue foods are rich in high-quality proteins and considered to be optimal resources for functional peptides preparation. This paper summarized the research status of calcium-chelating peptides and peptide-calcium complexes derived from blue food proteins, including sources, preparation, structural properties, characterization, and mechanisms of improving calcium bioavailability. The molecular weights of calcium-chelating peptides identified from blue food proteins are between 200 and 2000 Da, which rich in Glu, Asp, Gly, Pro, Leu and Val. The carbonyl/carboxy oxygen, amino nitrogen, and phosphate groups are the chelating sites for calcium. Calcium chelation caused structural and morphological variation in peptides. Peptide-calcium complexes not only improve cellular calcium absorption via multiple cellular pathways, promote the differentiation of osteoblast precursor cells, but also enhance bone status in rats via increasing serum calcium levels, improving bone parameters, and modulating intestinal flora. This review will provide valuable insights into utilization of calcium-chelating peptides and peptide-calcium complexes obtained from blue food proteins as dietary calcium supplements.