What is phenylketonuria and is aspartame safe for people with this condition?

Phenylketonuria (PKU) is a rare inherited disease in which individuals cannot properly metabolize the amino acid phenylalanine. In the United States, one in 15,000 babies is born with PKU. People with PKU don’t have enough of the enzyme needed to break down the amino acid phenylalanine. Because of this, phenylalanine can accumulate in the blood and brain fluid, and cause health problems, including mental retardation, if not treated early in life.

Routine screening of newborns for PKU is required by law in the U.S. and many other countries. Early detection of PKU and subsequent treatment with diets low in foods that contain phenylalanine, help children with PKU enjoy healthy lives. People with PKU are placed on a phenylalanine-restricted diet from birth until adolescence or later. Women with PKU must remain on the diet throughout pregnancy. Phenylalanine is found in common protein-containing foods such as chicken, hamburger, milk and vegetables, and is a component of aspartame. Individuals with PKU must consider aspartame as an additional source of phenylalanine. All products containing aspartame in the US feature the statement: "Phenylketonurics: Contains Phenylalanine."