Improved absorption of caseinophosphopeptide-bound iron: role of alkaline phosphatase.
Hydrolysis of proteins could lessen their inhibiting effect on the poor absorption of cow's milk iron (Fe), which is responsible for the high incidence of Fe deficiency worldwide. When bound to Fe, caseinophosphopeptides (CPP) derived from milk proteins resist luminal digestion, enhance Fe solubility and could improve its bioavailability; brush border enzyme alkaline phosphatase activity could influence iron absorption by releasing free Fe; this study assessed its role in the absorption of CPP-bound Fe. Rat duodenal loops were perfused with Fe gluconate or Fe bound to the CPP of beta casein [beta-CN (1-25)], with or without the addition of an inhibitor of alkaline phosphatase, Na2WO4. The uptake of Fe-beta-CN (1-25) was greater than Fe gluconate. Na2WO4 enhanced the uptake of Fe-beta-CN (1-25) and not of Fe gluconate. So the release of free, insoluble Fe, by alkaline phosphatase seems to be prevented by providing Fe in the Fe-beta-CN (1-25) complex form. Its good disappearance rate makes beta-CN (1-25)-bound Fe a candidate for food fortification.
Laboratoire de Physiologie Digestive et Nutritionnelle, CHU de Caen, F-14033 Caen Cedex, France.
Bertille
B
Ani-Kibangou
Saïd
S
Bouhallab
Daniel
D
Mollé
Gwénaële
G
Henry
François
F
Bureau
Dominique
D
Neuville
Pierre
P
Arhan
Dominique
D
Bouglé
D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D001682:Biological Availability; D002364:Caseins / Q000493:pharmacokinetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D007408:Intestinal Absorption; D007501:Iron / Q000493:pharmacokinetics*; D010446:Peptide Fragments / Q000493:pharmacokinetics*; D010477:Perfusion; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D017973:Tungsten Compounds / Q000494:pharmacology
D002364:Caseins; D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D017973:Tungsten Compounds; C412562:caseinophosphopeptide 1-25; C025399:sodium tungstate(VI); D007501:Iron; D000469:Alkaline Phosphatase