Aspartame, the methyl ester of the dipeptide formed from combining phenylalanine and aspartic acid, was approved by the US Food and Drug Administration (FDA) in July 1981. FDA monitors complaints from consumers and health professionals through the Adverse Reaction Monitoring System, a passive surveillance program FDA has received 251 reports of seizures that have been linked to ingestion of aspartame by consumers. In most cases, information obtained from the complainants' medical records as well as data on consumption patterns, temporal relationships, and challenge tests did not support the claim that the occurrences of the seizures were linked to consumption of aspartame.