Phenylketonuria, or PKU, is a rare genetic condition in which a person is unable to digest a component of protein, the amino acid phenylalanine. This causes phenylalanine levels to rise high enough to cause brain damage. Left untreated, PKU causes mental retardation and other complications, but this can be prevented with a special low-protein diet. So long as phenylalanine is strictly limited, people with PKU can lead healthy lives.
Avoid
Since high protein foods contain high amounts of phenylalanine, you will need to avoid them. This includes milk, eggs, cheese, nuts, soy, beans, chicken, beef and other meats, fish, chocolate and peas. You will also have to avoid diet foods and sodas, along with some medications, that contain the artificial sweetener aspartame because it increases phenylalanine levels.
Limit
Some foods are low in protein but still contain some phenylalanine so you will have to watch how much of these foods you eat. Some people with PKU can tolerate more phenylalanine than others, according to MayoClinic.com. Your doctor will figure out the safe level for you to consume by monitoring your blood levels of phenylalanine along with your diet. The idea is to limit phenylalanine to just the amount you need for good health but no more. Then your doctor will give you a target and you will need to track your intake each day to make sure you don't exceed it. Some of the foods you will have to limit your consumption of include pasta, rice, bread, cookies and some fruits and vegetables like corn and potatoes. Another option is to buy low-protein versions of these foods, which are available from specialty retailers.
Formula
If you have a baby with PKU, you will have to purchase a special phenylalanine-free formula. Babies who are not given this strict diet can develop mental retardation in the first year of life, according to MedlinePlus. Older children and adults with PKU still need to drink a phenylalanine-free formula every day, though it is different from the one given to infants. This helps people with PKU get enough protein and nutrition without raising phenylalanine levels too high.
Tips
If you have PKU you will need to follow a low phenylalanine diet for life to prevent complications that can interfere with thinking, memory, attention and problem solving, according to the University of Washington's Cristine M. Trahms Program for Phenylketonuria. A dietitian with experience in treating PKU can make that easier by helping you learn how to plan menus and cook foods that are low in phenylalanine but still tasty. She may also help you set up a food diary or computer program to track your phenylalanine intake or help you find financial assistance to help pay for the costs of phenylalanine-free formulas and special low-protein foods.
