Problems related to diet management of maternal phenylketonuria.

Provision of nutritionally complete elemental diets for pregnant women with PKU requires greater knowledge of 'conditionally' essential nutrient requirements than is presently available as well as application of known information. Formulation of elemental products needs to be improved to enhance aroma and taste and to decrease osmolality. Designers of the metal and vitamin components should keep in mind that a major portion (70-80%) of most of these nutrients must be obtained from the elemental products. Thus deletion of suspected essential minerals or vitamins could cause serious deficiencies. On the other hand, knowledge of appropriate ratios that make for improved trace metal absorption should be applied. Clinical nutritionists need to assist patients in selection of foods that are low in binding substances and provide 'conditionally' essential nutrients in adequate amounts. Closer cooperation between clinical nutritionists, nutrition scientists and food technologists should result in improved elemental products for care of pregnant women with PKU.