Phenylketonuria
Published May 9, 2026
In phenylketonuria (PKU), your body can't process phenylalanine, an amino acid in most foods. Read about genetics, screening, and special diets.
<p>Phenylketonuria (PKU) is a type of <a href="https://medlineplus.gov/aminoacidmetabolismdisorders.html" target="blank" rel="noopener noreferrer nofollow">amino acid metabolism disorder</a>. It is inherited. If you have it, your body can't process phenylalanine (Phe). Phe is an amino acid, a building block of proteins. It is in almost all foods. If your Phe level gets too high, it can damage your brain and cause severe intellectual disability. All babies born in U.S. hospitals must now have a <a href="https://medlineplus.gov/newbornscreening.html" target="blank" rel="noopener noreferrer nofollow">screening</a> test for PKU. This makes it easier to diagnose and treat the problem early. </p> <p>The best treatment for PKU is a diet of low-protein foods. There are special formulas for newborns. For older children and adults, the diet includes many fruits and vegetables. It also includes some low-protein breads, pastas, and cereals. Nutritional formulas provide the vitamins and minerals you can't get from their food.</p> <p>Babies who get on this special diet soon after they are born develop normally. Many have no symptoms of PKU. It is important to stay on the diet for the rest of your life.</p> <p>NIH: National Institute of Child Health and Human Development</p> <hr/> <p><em>Source: NIH MedlinePlus — <a href="https://medlineplus.gov/phenylketonuria.html" rel="noopener noreferrer nofollow" target="blank">https://medlineplus.gov/phenylketonuria.html</a></em></p>
Originally published at https://medlineplus.gov/phenylketonuria.html