PKU--or phenylketonuria--is a metabolic disorder in which the body cannot break down the amino acid phenylalanine. If phenylalanine builds up in the body because of the disorder, it can cause brain damage that leads to intellectual and developmental disabilities, according to the National Institute of Child Health and Human Development. Because phenylalanine and other amino acids are the building blocks for proteins, people with PKU must follow a strict, low-protein diet.
Fruits and Vegetables
Fruits and vegetables contain little, if any, protein, and they are safe to eat for people with PKU, according to the National Institute of Child Health and Human Development. In fact, because protein is so common in foods, fruits and vegetables are often the main components of the diet for people who have PKU.
Grain products, such as those containing wheat or rice, typically contain at least some protein. People with PKU can typically eat some grains, but they must limit and divide the quantities, because eating too much at once can cause problems. People who have PKU can tolerate some phenylalanine in the diet; in fact, the body requires some protein. MayoClinic.com advises that people with PKU devise meal plans with the total amount of phenylalanine in mind.
Because a diet lacking in protein is also lacking in several essential vitamins and minerals, people who have PKU must also consume special formulas to prevent nutrient deficiencies and help keep them healthy. These formulas--used by babies, children and adults with the condition--contain vitamins, minerals and protein but are free of phenylalanine, according to the University of Maryland Medical Center.