The impact of protein substitute on the nutrition status, growth, and neuropsychological performance of children and adults with phenylketonuria

People with phenylketonuria (PKU) who follow a low-phenylalanine diet are required to take protein substitute to ensure adequate consumption of protein, energy, and other nutrients. The need for protein substitute has been established through clinical experience and observational data. Randomised, controlled trials are needed to confirm this need as well as its proper dosage and frequency of use. We performed a systematic review of randomised control trials investigating the impact of the use, dosage, and distribution of protein substitute on physical and neuropsychological outcomes in the treatment of PKU. Trials of children and adults diagnosed with PKU in the newborn period who were treated early and continuously were included. We planned to pool the results of the trials to estimate treatment effect. Three trials met the inclusion criteria for the review. One trial evaluated the impact of protein substitute versus no protein substitute on neuropsychological status, plasma amino acid concentrations, and nutrient intake. The remaining two trials investigated the impact of differing dosages of protein substitute on plasma amino acid concentrations and nutrient intake. No trials investigating daily protein substitute distribution were eligible for inclusion in the review. Results are presented in text form only since adequate information for data pooling was not provided. The investigators are being contacted for further information. Currently data are insufficient to reach any conclusions regarding the use, dosage, and distribution of protein substitute in the treatment of PKU. Further randomized or controlled clinical trials are needed to provide evidence for the effectiveness, dosage, and distribution of protein substitute in the treatment of PKU.