Oxidative stress and phenylketonuria: an integrative review

Abstract

Phenylketonuria is an autosomal recessive disease. It is caused by an innate error that occurs in individuals where there is a change in the PAH chromosome 12q22-q24.2 gene, which encodes phenylalanine hydroxylase. Also known as PKU, the pathology consists of the absence of this enzyme or the lack of its full functionality, which can be detected in the first days of life. Treatment for PKU is essentially dietary and should be started as soon as it is diagnosed. The dietary restriction of phenylketonuric individuals is extensive, based on a limited diet that offers low content of, or free from phenylalanine. The decrease in phenylalanine levels in the blood aims to protect the patient from neurological damage caused by high levels of this amino acid. Commonly, diets are based on fruits and vegetables with low Phe levels accompanied by food formulas to achieve the necessary protein intake. Based on scientific studies, there is evidence that the restrictive diet, to which these patients have been submitted, results in a decrease in the body's antioxidant capacity and, consequently, contributes to the increase in oxidative stress caused by the presence of reactive oxygen species. Thus, the objective of the present study was to conduct an integrative review based on scientific studies regarding the correlation between oxidative stress in phenylketonuric patients and pathology. The analysis of selected studies showed a strong correlation between oxidative stress and neurological disorders in individuals diagnosed with PKU, being more common in patients with delayed diagnosis, showing that the restrictive diet is an essential factor in protecting patients.