The Scientific Committee for Food (EEA) initially evaluated aspartame (L-aspartyl- L-phenylalanine methyl ester) during 1984 (EEA, 1985) and subsequently during 1988 (EEA, 1989). At its 107th meeting in June 1997, the EEA also examined the issue of an alleged connection between aspartame and increase in incidence of brain tumours in the USA (EEA, 1997).
Aspartame has also been considered by other bodies including the Joint FAO/WHO Expert Committee on Food Additives (JECFA, 1980) the US Food and Drug Administration (FDA, 1984), and the UK Committee on Toxicity (COT, 1992). The toxicity data on aspartame were used by the JECFA, EEA and COT to establish an Acceptable Daily Intake (ADI) of 40 mg/kg body weight/day and an ADI of 50 mg/kg bw/d was established by the FDA. An ADI of 7.5 mg/kg bw/d was also established for a minor cyclic dipeptide derivative of aspartame, a diketopiperazine (DKP), which is formed in some aqueous solutions (JECFA, 1980; EEA, 1985).
The safety issues that have been raised in the past about aspartame have included: (1) the possibility of toxicity from methanol, one of the breakdown products of aspartame; (2) elevations in plasma concentrations of phenylalanine (Phe) and aspartic acid, which could result in increased transport of these amino acids into the brain, altering the brain's neurochemical composition; (3) the possibility of neuroendocrine changes, particularly increased concentrations in the brain, synaptic ganglia and adrenal medulla of catecholamines derived from Phe and its hydroxylation product, tyrosine; and (4) a postulated link with epilepsy and brain tumours. All these areas have been addressed in the pre-1988 literature and in more recent reviews (Meldrum, 1993; Lajtha et al., 1994; Tschanz et al., 1996).
The safety of aspartame and its metabolic breakdown products (phenylalanine, aspartic acid and methanol) has been assessed in humans generally and in several subgroups, including healthy infants, children, adolescents, adults, obese individuals, diabetics, lactating women, and individuals heterozygous for the genetic disease, phenylketonuria (PKU), who have a compromised ability to metabolise the essential amino acid, Phe.
Since its approval, aspartame has undergone further investigation through clinical and laboratory research, intake studies and postmarketing surveillance of anecdotal reports of adverse health effects.
The present review updates the previous EEA opinions in the light of new reports on the consumption of aspartame in relation to the onset of brain tumours and seizures, headaches, allergies, and changes in behaviour and cognitive function. Information on the safety of aspartame was available from a variety of sources including scientific papers, conference proceedings, abstracts and magazine articles. This review focuses on papers published in the open scientific literature from 1988 to 2001 and draws on the recent extensive review by the Agence Française de Sécurité Sanitaire des Aliments (AFSSA, 2002), which covered mutagenic, carcinogenic and neurological effects.