MODERATE AND HIGH AMOUNTS OF PROTEIN FROM CASEIN ENHANCE HUMAN ABSORPTION OF ZINC FROM WHOLE-WHEAT OR WHITE ROLLS

The enhancement of zinc absorption by protein was investigated using a broad range of ingested protein in combination with either whole-wheat or white rolls. Twenty or 40 g of protein from casein were added to rolls containing 10 g protein; zinc content was adjusted to 4 mg. The rolls were extrinsically labelled with Zn-65 and fed to 20 healthy participants. Zinc absorption was measured by whole body scintillation counting. Average (+/- SD) zinc absorption ranged from 8 +/- 4% for the whole-wheat rolls with the least protein to 26 +/- 7% for the white rolls with the most protein. Less zinc was absorbed from whole-wheat than from white rolls containing the same amount of zinc. The protein and type of flour did not interact to affect zinc absorption. As protein increased from 10 to 50 g, zinc absorption was enhanced with no indication that maximum enhancement had been achieved.