In the Food with vitamin D ( VitmaD ) study , we showed that common genetic variants rs10741657 and rs10766197 in 25-hydroxylase ( CYP2R1 ) and rs842999 and rs4588 in vitamin D binding protein ( GC ) predict 25 ( OH ) D concentrations at late summer and after 6-mo consumption of cholecalciferol ( vitamin D ) - fortified bread and milk .