Phenylalanine helps manufacture certain neurotransmitters that affect your emotions and behavior. Your body does not make phenylalanine, an essential amino acid. L-phenylalanine comes from protein foods, and D-phenylalanine is a synthetic version. DL-phenylalanine is a combination of food and laboratory sources. High doses of DL-phenylalanine may lead to side effects that include headaches, nausea and heartburn.
Taking phenylalanine doses higher than 5,000 milligrams a day can have toxic effects and cause nerve damage, according to the University of Maryland Medical Center. Excessive amounts of phenylalanine can result in migraine headaches and hypertension, or high blood pressure. Too much phenylalanine excites neurons in the brain and can cause cell death by overwhelming the brain network. Ingesting high quantities or using phenylalanine during pregnancy may cause irreversible brain damage and even death.
Taking liquid or supplemental forms of phenylalanine may rapidly increase levels of the amino acid in the brain. This can lead to headaches if you consume high doses. The artificial sweetener aspartame used in diet sodas and foods contains phenylalanine. You usually don’t need to concern yourself about consuming these products unless you consume excessive amounts, take certain medications for mental health conditions or suffer from sleep disorders, anxiety disorders and other emotional disorders. Pregnant women should consult their doctors about taking artificial sweeteners.
A rare disorder called phenylketonuria, or PKU, causes the lack of an enzyme that properly utilizes the amino acid, which builds up in the body as a result. People with the disorder need to avoid phenylalanine and usually meet their protein needs through supplements containing tyrosine, another amino acid. Normally phenylalanine converts to tyrosine while moving from the bloodstream to the brain. Tyrosine then builds brain chemicals that regulate energy needs.
While high doses of phenylalanine can result in headaches or more serious consequences, deficiencies of the amino acid can cause lack of energy or memory difficulties. Getting adequate amounts involves eating the protein foods you need in a well-balanced meal. Beef, poultry, fish, dairy products, nuts and seeds contain phenylalanine. Protein foods release amino acids into the bloodstream that make neurotransmitters, such as dopamine and norepinephrine, which provide a boost in energy and improve alertness. If you suspect phenylalanine causes your headaches, especially if you consume the amino acid in supplements or diet products, check with your doctor for dietary advice.