Phenylketonuria, or PKU is an inherited birth defect in which babies are born without the ability to properly break down an amino acid called phenylalanine. Phenylalanine occurs naturally in protein-rich foods. Excess intake of protein foods causes phenylalanine to build up in the body, which leads to damage to the brain and central nervous system, according to MayoClinic.org. Babies with positive PKU screening tests are placed on a special diet.
Low-Protein Foods
Phenylalanine is found in most foods that have protein. Babies diagnosed with PKU are usually placed on protein-free substitutes and special formulas without phenylalanine to prevent brain damage. If proteins containing phenylalanine are not avoided, mental retardation can occur by the end of the first year of life. The protein-free diet may be continued into adulthood. Older children and adults are allowed to eat low-protein foods such as enriched breads and cereals. Protein-rich foods such as meat, eggs, cheese, and nuts are not recommended for patients with PKU.
Essential Fatty Acids
The University of Maryland Medical Center advises patients with PKU to take essential fatty acids such as fish oil to replace the long chain fatty acid missing from protein-free or low phenylalanine diets. Essential fatty acids contain omega-3 and omega-6 fatty acids, which help to improve neurological development and functioning in children and adults with PKU.
Aspartame
Children and adults with PKU should avoid products that contain an artificial sweetener called aspartame, according to the University of Maryland Medical Center. Aspartame, which is sold under the brand name NutraSweet, contains phenylalanine. Aspartame is found in products such as chewing gum, fruit spreads, dairy products, candies and carbonated beverages.
Phenylketonuria Symptoms
Children born with PKU usually have no symptoms at birth. The damage from PKU can begin a week after a baby has started drinking breast milk or formula. Symptoms of PKU include skin rashes, seizures, body odor, mental retardation, small head size, hyperactivity, stunted growth, jerking movements of the arms or legs, tremors, unusual positioning of hands, delayed social skills, behavioral problems and lighter skin, hair and eyes, according to the University of Maryland Medical Center.
