# Do people with phenylketonuria (PKU) need to adhere to a diet for life? Canonical page: https://clinicsjo.com/en/faq/pku-diet-lifelong-commitment Language: en Category: pediatrics Publisher: ClinicsJo Published: 2026-09-13T17:52:51.592Z Content updated: 2026-09-13T17:52:51.592Z Translation (ar): https://clinicsjo.com/ar/faq/pku-diet-lifelong-commitment Yes, people with phenylketonuria (PKU) must adhere to a strict, low-phenylalanine diet for life. This commitment is essential to maintain their physical and mental health and to avoid serious complications resulting from the accumulation of phenylalanine in the body, particularly damage to the nervous system and brain [\[1\]](). Phenylketonuria is a rare genetic condition where the body cannot properly break down the amino acid phenylalanine, which is found in protein-containing foods. Without the enzyme required to break it down, phenylalanine levels accumulate in the body, which can cause damage to the central nervous system and the brain [\[1\]](). ## The Importance of Continuing the Diet in Adulthood Most experts recommend continuing the PKU diet for life. Studies have shown that people who maintain the diet into adulthood enjoy better physical and mental health compared to those who discontinue it [\[1\]](). If the diet is not followed, the buildup of phenylalanine can lead to severe intellectual disability, and problems such as attention-deficit/hyperactivity disorder (ADHD) may occur more commonly in those who do not adhere to a low-phenylalanine diet [\[1\]](). ## Dietary Components The diet requires careful supervision by a registered dietitian or healthcare provider. The diet involves avoiding protein-rich foods such as milk, eggs, and many other common foods. Artificial sweeteners such as aspartame must also be avoided because they contain phenylalanine [\[1\]](). For infants with PKU, special formulas are available, and they can safely breastfeed alongside the use of medical foods and appropriate monitoring of phenylalanine levels. Older children and adults use a different formula that provides the protein they need [\[1\]](). ## Early Diagnosis and Treatment Early diagnosis of PKU is crucial. All newborns in the United States are screened for PKU as part of routine newborn screening [\[2\]](). If the diet is followed closely, starting shortly after the baby's birth, the expected outcomes are very good. However, if treatment is delayed or the condition remains untreated, brain damage may occur [\[1\]](). You can learn more about this condition by visiting the page [Phenylketonuria (PKU): Early Diagnosis, Diet, and its Impact on Child Development (Arabic)](). ## Special Considerations for Women with PKU Women with PKU need to strictly follow the diet before pregnancy and throughout the duration of the pregnancy. This is very important because the accumulation of phenylalanine can harm the developing fetus, even if the child does not inherit the disease completely [\[1\]](). ## Medical references - [Phenylketonuria]() - [Phenylketonuria]() General health education; not a substitute for individualized clinical assessment. Citation URL: https://clinicsjo.com/en/faq/pku-diet-lifelong-commitment#answer