Issues in the dietary management of phenylketonuria: breast-feeding and trace-metal nutriture.

We have reviewed our experience with supplemental breast-feeding of the infant with PKU. Our results indicate no harmful nutritional effects of breast-feeding the child with PKU, in comparison with the traditional approach using formula or cow's milk for supplementation. In addition, breast-feeding may provide a source of emotional support for the mother during this difficult period of initial diagnosis and management. It is hoped that this may improve the family's adjustment to this chronic illness. Our work with breast-feeding led us to a consideration of trace-metal nutriture in children treated with these synthetic and semi-synthetic formulas. The results of these investigations suggest that there is a biochemically significant decrease in the bioavailability of zinc when these artificial formulas are used. While no clinical trace-metal deficiency has been described in treated PKU patients, we suggest that these nutritional deficits may relate to subtle abnormalities exhibited by these patients.