Aspartame Safety Concerns

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Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR

In response to research published by Italian scientists that suggests that the artificial sweetener aspartame can cause cancer, the U.S. consumer organization Center for Science in the Public Interest requested an urgent Food and Drug Administration (FDA) review of the product's safety in June 2007.

Aspartame, which has been on the U.S. market since 1981, is composed primarily of two common amino acids, aspartic acid and phenylalanine. Each of these is also a building block for conventional foods such as protein and natural flavor molecules. Before its FDA approval, the safety of aspartame was tested in over 100 scientific studies. These studies were carried out in both humans and laboratory animals and included studies of rats that were fed aspartame in doses greater than 100 times the amount that humans would normally consume.

The data that sparked the controversy were from a report by researchers at the European Ramazzini Foundation (ERF) in Bologna, Italy, published in 2005. The scientists carried out tests of over 4,000 rats that regularly consumed high doses of aspartame and were allowed to live until they died naturally. Scientists from ERF concluded from their study that aspartame causes cancer and that current uses and consumption of the sweetener should be reevaluated.

The controversy prompted a review of the data by the European Food Safety Authority (EFSA) in May 2006. At that time, an EFSA press release stated that EFSA's review of ERF's study concluded, among other things, that on the basis of all evidence currently available to EFSA, ERF's conclusion that aspartame is a carcinogen is not supported by the data and the EFSA sees no need to further review its earlier scientific opinion on the safety of aspartame or to revise the Acceptable Daily Intake.

Upon learning of the ERF study results, the U.S. FDA also requested the study data from ERF to evaluate the findings. On Feb. 28, 2006, the agency received a portion of the data requested. The FDA issued a statement in May 2006 which stated:

We are actively reviewing the data provided by ERF and will complete our review of those data as soon as possible. When FDA completes its review of the ERF study data, it will announce its conclusion.

Since it was first approved for use in the United States, the safety of aspartame has been questioned by some. To date, however, the agency has not been presented with scientific information that would support a change in our conclusions about the safety of aspartame. Those conclusions are based on a detailed review of a large body of information, including more than 100 toxicological and clinical studies regarding the sweetener's safety.

In summary, the FDA currently supports its previous position regarding the safety of aspartame. However, because of its phenylalanine component, aspartame does carry a risk for people with the rare genetic disorder phenylketonuria. People who have this disorder should avoid or restrict aspartame use because of their body's difficulty in metabolizing phenylalanine.