Journal of J. Trace Elements Med. BioI. Vol. II, pp. 143-149 (1997) Trace Elements In Medicine and Biology © 1997 by Gustav Fischer Verlag Effect of Casein Phosphopeptides on Zinc and Calcium Absorption from Bread Meals M. HANSENI, B. SANDSTROM, M. JENSEN* and S. S. S0RENSEN* Research Department of Human Nutrition/LMC Centre for Advanced Food Studies, The Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark *Department of Clinical Physiology and Nuclear Medicine, The National University Hospital, Blegdamsvej 9, DK-2100 Copenhagen 0, Denmark (Received February/Mai 1997) Summary Animal studies suggest that casein phosphopeptides (CPP), fOlmed by proteolytic digestion of casein, have a positive effect on Ca availability. The aim of this study was to investigate the ability of CPP to improve Zn and Ca absorption from phytate-containing bread meals. Secondly, it was tested whether the Ca content of the meal influenced the effect of CPP on Zn absorption from a high-phytate meal. Zn and Ca absorption from single model meals was determined by extrinsic labeling with 65Zn and 47Ca and measurement of whole-body reten- tion. Thirty-one healthy adults (19-30 y) divided into three groups received one of three meal types based on white-wheat rolls with different phytate and Ca content: A: low-phytatelhigh-Ca (n= I 0), B: high-phytatelhigh- Ca (n=lO) and C: high-phytateflow-Ca (n=11). Each individual received the same meal type at three different occasions with 0, 250 and 1000 mg CPP added. CPP had no effect on Zn absorption: A: 14.3±4.4% (X±SD) (0 mg CPP), 16.7±6.6% (250 mg CPP) and 16.0±8.8% (1000 mg CPP); B: 7.0±1.6%, 7.7±3.0% and 8.0±2.6%; C: 7 .7±2.5%, 7.0±2.3% and 6.5±1.6%, respectively. Addition of 1000 mg CPP reduced fractional Ca absorption from meal A: 33.8±7.1 %, 30.5±6.3% and 25.9±8.7% (p<0.05), whereas CPP had no effect in meal B: 29.3±8.3%, 27.0±7.4% and 27.6±11.0%. However, the absolute quantity of Ca absorbed was unaffected. In conclusion, Zn and Ca absorption from these meals were not significant! y influenced by the addition of CPP. Ca addition could not explain the failure of CPP to improve Zn absorption. Keywords: Bioavailability, casein, phytate, whole-body retention, radioisotopes. Abbreviations: CPP, casein phosphopeptides; PABA, p-amino benzoic acid. Introduction gesting a stimulatory effect of milk on Zn absorption from other food items as well. Zn and Ca absorption is high from milk and dairy The chemical environment of a meal influences lumi- products (1,2) and low from phytate-containing foods nal solubility of the minerals and is considered an impor- (3,4). In addition, milk added to a phytate-containing tant determinant for bioavailability (3,6). Utilization of meal has been shown to improve Zn absorption (5), sug- Zn and Ca is inhibited when they are bound in tight com- plexes with, e.g., phytate in the food. On the other hand, ITo whom correspondence should be addressed. low-molecular-weight compounds may act as ligands and