Food protein-derived calcium chelating peptides: A review

Calcium is known as an essential nutrient in the human body. Insufficient calcium uptake results in metabolic bone disease such as rickets in children and osteoporosis in the elderly. Chelated calcium has been proposed as a superior candidate to ionized calcium for improving calcium absorption and bioavailability and might have potential application in the management of calcium deficiencies for human beings. A number of calcium chelating peptides with the ability to enhance calcium absorption and bioavailability have been discovered and characterized. This review outlines the sources of food-derived calcium chelating peptides, and focuses on the peptide-calcium chelating mode as well as calcium absorption and bioavailability enhancement potential of calcium chelating peptides. Calcium chelating peptides have been identified from different food sources, including animal sources, aquatic sources and plant sources. These peptides could chelate with calcium via specific groups, such as phosphate group or carboxyl group. Furthermore, some peptides such as casein phosphopeptides (CPPs) and soybean peptides, have been reported to improve intestinal calcium absorption by in vitro cell models and increase incorporation of calcium into bones by rat models. Currently, with more and more calcium chelating peptides being discovered and characterized from different food sources, more data on the peptide-calcium chelating mode and the effect of peptides on calcium absorption and bioavailability, as is the case with CPPs, would be of particular value for their incorporation as functional ingredients or calcium supplements.