What Food Group Must a Person With PKU Avoid?

Eggs, cheese and other high-protein foods contain phenylalanine.
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If you or a family member has PKU, foods high in phenylalanine, an essential amino acid, are off the menu or severely limited. People with PKU, the common name for phenylketonuria, lack an enzyme that breaks down phenylalanine, so the amino acid builds up in the bloodstream, potentially causing physical and mental changes. Avoiding foods that contain PKU prevents symptoms from occurring; the PKU diet is a lifelong endeavor. Work with a dietitian and your doctor to devise a diet that works for you.

High-Protein Sources

    Because phenylalanine is an amino acid, it's not surprising that high-protein foods are the primary foods to avoid if you have PKU. All types of meat, including pork, chicken, beef and fish, as well as milk, eggs, nuts, cheese and soybeans are very high in phenylalanine.

Starches, Vegetables and Fruits

    Breads, rice, peas and other starches and starchy vegetables also contain some phenylalanine, although not as much as high-protein meat, nuts and beans. You may be able to eat small amounts of these foods. Foods that you might not suspect to be high in phenylalanine include two widely favorite foods: chocolate candy and beer. While fruits and vegetables contain small amounts of phenylalanine, you need a small amount to meet your protein needs. You can buy special low-protein breads and pastas that contain less phenylalanine.

Foods Containing Aspartame

    You might be wondering what aspartame, an artificial sweetener, has to do with an amino acid such as phenylalanine. Aspartame releases phenylalanine when you digest it. Taking aspartame off the table means eliminating any diet sodas or any foods containing the sweetener.

Infant Diet

    In the United States, babies routinely are tested for PKU after birth, so affected infants can start a special diet before phenylalanine levels build up and cause permanent damage. Since babies drink milk exclusively, PKU causes a total diet revision for an infant. A special formula, called Lofenalac, will not only meet your baby's needs but can serve as a protein source throughout life, according to MedlinePlus. However, since infants need all the amino acids for proper growth and development, a small amount of formula or breast milk can meet their phenylalanine needs. Talk with your child's doctor to determine a course of action.

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