Measurement of intestinal absorption of calcium-casein peptide in rats by portal cannulation

The intestinal absorption of calcium-casein peptide (CaCP) was investigated in rats under unanesthetized and unrestrained conditions using a new modified portal cannulation method. CaCP is a hydrolysate of calcium caseinate with an average peptide chain length of 4.7 and containing 7.3% free amino acids. We compared the intestinal absorption of CaCP with that of an amino acid mixture (AAM) corresponding to CaCP by determining total amino acids, total essential amino acids and individual amino acids in portal blood after a single dose delivered into the duodenum. It was found that CaCP was absorbed more rapidly than AAM, and that the amount of amino acids absorbed was also increased significantly. In particular, the rate of absorption of essential amino acids of CaCP was markedly higher than that of AAM. However, the proportion of each amino acid absorbed in the portal blood from CaCP was not necessarily similar to the amino acid composition administered. These results suggest that the intestinal absorption of CaCP is considerally superior to that of AAM, and that CaCP could thus have improved nutritional effects.