What are the Harmful Effects of Phenylalanine?

Phenylalanine encourages seizures, especially in individuals with the rare disorder PKU or who carry the PKU gene. Phenylalanine’s toxic effects usually don’t appear in short-term testing, but this amino acid does accumulate in the human body, slowly affecting it over time. Phenylalanine can block the normal production of serotonin, a brain chemical that stimulates an increased craving for carbohydrates, sleep disorders, PMS and severe mood swings (not related to hormonal cycles), aggressive mood swings (not related to hormonal cycles), aggression, and severe depression.