Availability of calcium and phosphate in calcium caseinate.

Calcium caseinate was fed to children aged 8-11 yr as a beverage (20 g dispersed in water, milk or buttermilk) twice daily over a period of 10 days. 95% of the 400 mg Ca in the caseinate was absorbed and 60% of this was ultimately retained: 75% of the 312 mg P provided by the caseinate was absorbed and 70% was ultimately retained. This finding was further subtantiated by rat feeding experiments. The rate of absorption of Ca from calcium caseinate when administered via stomach-tube to normal rats or injected into the small intestine in anaesthetized animals was comparable to that of inorganic Ca similarly administered. The trypsin-resistant phosphopeptides released during digestion of casein in the gut do not seem to survive sufficiently long to interfere with the absorption of Ca.