Researchers noticed that kids with PKU who went off of their diet had a higher chance for learning and behavioral problems as they got older. Teenagers and young adults who returned to the PKU diet reported that they felt better both mentally and physically. This is why we say now that it is important to make the low Phe diet plus formula a permanent part of your life. The formula is an essential part of the PKU diet. Phe is one of a group of chemicals called amino acids.
Amino acids are the building blocks that make protein in our bodies.
Without amino acids, our bodies couldn't make the protein needed for growth and all around well being. Most foods with protein contain Phe. Because of this, people with PKU have to avoid most foods with protein. Their bodies aren't getting the protein they need to stay healthy. If we can't give the body whole protein, then we have to feed it amino acid building blocks so that the body can make protein on its own.