Aspartame Scientific Research Summary

Aspartame, a high-intensity sweetener composed of L-alpha-aspartyl-L-phenylalanine methyl ester, was approved more then 20 years ago by regulatory agencies. The introduction of aspartame allowed people with diabetes to enjoy good-tasting foods and still comply with dietary requirements. Aspartame-containing products have been shown to be useful as part of a comprehensive multidisciplinary program to promote weight loss and control of body weight in obese individuals.

• Numerous studies using internationally accepted models for safety assessment were conducted to establish the safety of aspartame.
  
• Extensive toxicologic and pharmacologic research was done in laboratory animals using much greater doses of aspartame than people could possibly consume.
  
• In addition, the safety of aspartame and its metabolic constituents was further confirmed in several human sub-groups of the population including: healthy infants, children, adolescents, and adults, obese individuals, diabetics, lactating women, and individuals heterozygous (PKUH) for the genetic disease, phenylketonuria (PKU), who have a decreased ability to metabolize the essential amino acid, phenylalanine.
  
• The results of the animal and human studies provided evidence that aspartame consumption is safe, including by pregnant women and children. Aspartame has been approved by regulatory agencies in over 100 countries worldwide.

After aspartame was approved, consumption studies demonstrated that actual aspartame intake at the 90th percentile was only 5-10% of the acceptable daily intake, thus providing small amounts of aspartate, phenylalanine, and methanol to the diet.

• Scientific studies, however, continued to be conducted during the postmarketing period.
  
• The main reason for these studies? Assertions of potential toxicity of its three metabolic components when given in extremely high doses.
  
• These issues centered on potential excitotoxicity of aspartic acid, potential effects of phenylalanine on brain function, and toxicity of methanol’s formate metabolite.
  
• Results of the research showed that it is not possible for a human to ingest enough aspartame to raise plasma concentrations of its metabolic constituents to those associated with adverse effects.

Additionally, a postmarketing surveillance program was developed to document and further evaluate anecdotal reports of adverse health effects from some consumers. Although a cause-and-effect relationship could not be established from these reports, the information was used to guide additional research efforts. Further studies evaluated possible associations between aspartame and headaches, seizures, behavior, cognition, and mood, as well as allergic-type reactions. Studies were also done to evaluate the safety of aspartame use by potentially sensitive subpopulations (i.e., individuals heterozygous for the rare genetic disease, phenylketonuria, individuals with Parkinson’s disease, dizziness, depression, liver disease, and renal disease). Additionally, further evaluations of aspartame and the endocrine system were completed. In addition, an allegation that aspartame may be associated with brain tumors in humans was raised by a long time aspartame critic almost 20 years after he first raised the same issue in animals. This allegation was evaluated by scientists and regulators with the conclusion that the claims were not valid.

Much of the scientific research, both before and after regulatory approval, has focused on the safety of the components of aspartame – amino acids, aspartic acid and phenylalanine, and a small amount of methanol – all of which are found naturally in the diet. It is important to note that these components are used by the body in the same ways as when they are derived from foods, such as meat, milk, fruits, and vegetables. Further, the components of aspartame are derived from these common foods in much larger amounts. For example, a glass of milk provides about 6 times more phenylalanine and 13 times more aspartic acid and a glass of tomato juice provides about 6 times more methanol than an equivalent volume of beverage sweetened 100% with aspartame.

Thirty years of research has been conducted on aspartame safety. The testing of aspartame has been far beyond the standard safety testing required to evaluate the safety of a food additive. When all the research on aspartame, including evaluations in both the pre-marketing and postmarketing periods, is examined as a whole, it is clear that aspartame is safe, and there are no unresolved questions regarding its safety under conditions of intended use.

Adapted from Regulatory Toxicology and Pharmacology, Vol. 35, Number 2, April 2002.

Scientific Research Summary Continued