Ann Allergy. 1988 Dec;61(6 Pt 2):63-9.

Aspartame intolerance.

Garriga MM, Metcalfe DD.

Mast Cell Physiology Section, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland.

Aspartame is a food additive marketed under the brand name Nutrasweet®. Aspartame is a white, odorless, crystalline powder and consists of two amino acids, L-aspartic acid and L-phenylalanine. It is 180 times as sweet as sugar. The Food and Drug Administration (FDA) first allowed its use in dry foods in July 1981 and then approved its use in carbonated beverages in July 1983. It has subsequently been approved for use in a number of materials including multivitamins, fruit juices, stick-type confections, breath mints, and iced tea. The FDA requires the statement "phenylketonurics: contains phenylalanine" on labels of food products containing aspartame because individuals with phenylketonuria (PKU) must restrict their intake of phenylalanine. Aspartame is judged to be free of long-term cancer risks. Aspartame is not stable under certain conditions including baking and cooking, and prolonged exposure to acid conditions. In such situations it loses its sweetness. Products formed from aspartame include its component amino acids (phenylalanine and aspartic acid), methanol, and diketopiperazine (DKP). Animal studies show DKP to be nontoxic. Methanol occurs in small amounts and does not exceed that formed during consumption of many foods including fresh fruits and vegetables. FDA's Center for Food Safety and Applied Nutrition (CFSAN) monitors aspartame's safety in part through reports of adverse reactions. After aspartame was approved for use in carbonated beverages, the FDA received an increased number of reports concerning adverse reactions related to aspartame. The Centers for Disease Control (CDC) reviewed these reports, which included complaints of neurologic, gastrointestinal, and allergic reactions. In November of 1984, the CDC reported that it found no conclusive evidence that aspartame was responsible for adverse reactions. CFSAN reported as of January 1987 that it had received about 3,000 adverse reaction reports concerning aspartame, but could not definitely state a cause and effect relationship. Most reactions were mild. Symptoms were categorized as neurological, behavioral, gastrointestinal, allergic, menstrual, and other. Such complaints have led clinical investigators to begin to examine these complaints. Such studies are often time consuming and difficult. Experimental protocols are designed to use double-blind challenge procedures. To date, relevant published papers are few, reports documenting allergic reactions are rare. In summary, aspartame is a chemically simple compound, approved for use as a sweetener. Concern has been expressed over its widespread use but analysis of adverse reaction reports and available clinical data suggests that it is remarkably safe.