Side Effects of Phenyalanine

Phenylalanine is an amino acid the body needs. It can be found in a variety of natural foods, such as dairy products, fish, nuts and poultry. It is also an additive in artificially sweetened foods and beverages, such as diet soft drinks. Though it is safe for the majority of people to consume, some have a harsh reaction to it. People who suffer from a rare condition called phenylketonuria, or PKU, should avoid it entirely, according to the Mayo Clinic. These people lack an enzyme the body needs to metabolize phenylalanine properly and thus can end up with harmful levels of the amino acid in the body.

Seizures

According to alternative health and holistic nutrition specialist Janet Hull, phenylalanine may cause seizures, episodes of disturbed brain function, for people who carry the PKU gene. It is a rare but serious side effect and is one of the reasons women who are pregnant or nursing are encouraged not to consume products that contain the amino acid.

Hyperactivity

Phenylalanine can cause hyperactivity or anxiety in children, particularly if the child has been diagnosed with attention deficit hyper activity disorder (ADHD). Because of this many health care professionals suggest children avoid foods and beverages that contain phenylalanine, according to the University of Maryland Medical Center (UMMC).

Skin Darkening

Research has shown that people who suffer from vitiligo, or loss of skin pigmentation, may develop irregular skin darkening when UVA radiation, which is used to treat vitilgo, is combined with phenylalanine. Some studies show that phenylalanine intake for these people is safe under doctor's supervision, UMMC reports.

Effects on Medication

Studies have shown that certain medications will stop working properly when combined with phenlyalanine intake. Those who take anti-psychotic drugs are at particular risk. For this reason, a physician should be consulted before combining the amino acid as a supplement or food additive prior to use, according to Beth Israel Deaconess Medical Center.