PKU is a treatable disease. Treatment involves a diet that is very low in phenylalanine, particularly when the child is growing. The diet must be strictly followed. This requires close supervision by a registered dietitian or doctor, and cooperation of the parent and child. Those who continue the diet into adulthood have better physical and mental health than those who don't stay on it. "Diet for life" has become the standard most experts recommend. It is especially important for women who have PKU to follow the diet before conception and throughout pregnancy.
There are large amounts of phenylalanine in milk, eggs, and other common foods. The artificial sweetener NutraSweet (aspartame) also contains phenylalanine. Any products containing aspartame should be avoided.
There are several special formulas made for infants with PKU. These can be used as a protein source that is extremely low in phenylalanine and balanced for the remaining essential amino acids. Older children and adults use a different formula that provides protein in the amounts they need. People with PKU need to take formula every day for their entire life.
Taking supplements such as fish oil to replace the long chain fatty acids missing from a standard phenylalanine-free diet may help improve neurologic development, including fine motor coordination. Other specific supplements, such as iron or carnitine, may also be needed.