The PKU diet is necessary for people who have a genetic disorder called phenylketonuria (PKU). People with PKU are missing an enzyme that allows the body to convert phenylalanine (an amino acid) to tyrosine (another amino acid). Phenylalanine builds up and causes brain damage; so everyone with PKU should avoid high-protein foods.
Babies and infants with PKU need a special formula that does not contain phenylalanine.
It is absolutely crucial that babies, toddlers, and children do not eat high-protein foods because the brain is growing rapidly. A very rigid diet must be followed. All high protein foods should be avoided.
Protein-rich foods include:
- meat
- fish
- poultry
- Milk
- yogurt
- cheese
- eggs
- walnuts
- seeds
- vegetables
- peanut butter and other nuts
Dishes, snacks, and meals made from these foods, such as pizza, cake, cookies, hamburgers, hot dogs, ice cream, yogurt, and many other foods, should also be avoided. Even things like bread and some types of cereals can have too much protein. Aspartame should also be avoided as it is a combination of aspartic acid and phenylalanine.
Children and teens with PKU can eat fruits and vegetables and small amounts of cereal and crackers because those foods are low in protein. Adults should also stick fairly closely to the diet.
However, the PKU diet is too low in protein for normal health, so children and adults with PKU need to consume special protein drinks formulated without phenylalanine.
In addition, this diet must be followed for life, and blood tests are regularly performed to monitor the levels of phenylalanine in the body.
Is PKU common?
According to the National PKU Alliance, about one in 15,000 babies has PKU. Babies in the United States and many other countries are tested soon after birth, and as long as babies and children adhere to the diet, their brains will develop normally.
Adults with PKU may have a little more leeway with protein intake because the brain is fully developed, but PKU doesn’t go away, and consuming too much phenylalanine can cause mood problems and memory loss.
