Is aspartame related to cancer?
The vast body of research conducted on aspartame over the last 30 years has found it does not cause cancer in humans, yet some people doubt the strength of the scientific evidence and continue to raise questions about a possible cancer risk related to aspartame. Some of these doubts are fueled by the publication of laboratory studies suggesting a carcinogenic effect from aspartame in rodents. These studies and the headlines they provoke have resulted in aspartame being one of the most closely monitored additives in the food supply since it was first introduced in 1981.
A comprehensive review of the safety of aspartame based on current usage levels and available toxicological and epidemiological studies was published by Magnuson et al., in 2007. The review was conducted by an independent panel of recognized experts who examined over 500 published scientific studies, articles and reports looking at mechanisms of aspartame absorption and metabolism, worldwide consumption levels and toxicology data. Throughout the period of the review the identity of the sponsor was not known to the panelists and the identities of the panelists were unknown to the sponsor.
Ramazzini Institute Study Reviewed
Included in the review by Magnuson et al., were two studies by Soffritti et al. (2005, 2006) from the European Ramazzini Foundation on Oncology and Environmental Sciences (ERF), also known as the Ramazzini Institute, that drew attention when they reported aspartame increased malignancies in rats. Many flaws were identified in these studies and delineated in Magnuson’s review based on both the published data and additional information obtained in an unpublished report provided by the ERF to the National Toxicology Program and European Safety Authority (EFSA).
EFSA requested the additional unpublished information because it was specifically tasked to determine whether previous safety evaluations of aspartame and the ADI needed to be revised based on the ERF studies. The EFSA conducted its own investigation of the data and determined the tumors reported by the studies conducted by Soffritti et al., were generally unrelated to the aspartame treatment, showed no dose-response relationship or were of no relevance for humans. In its published opinion issued in May 2006, the EFSA concluded there was no change in the safety of aspartame or reason to revise the ADI based on the available evidence. The U.S. Food and Drug Administration subsequently issued a statement in support of the EFSA findings and said it did not plan to change its position on the safety of aspartame.
In 2010 Soffritti et al. published another carcinogenicity study, this time related to transplacental exposure to aspartame in mice. Again, the EFSA was asked to provide scientific advice on the study. In its 2011 statement, the EFSA found the results could not be interpreted based on the information available in the publication, but noted the type of tumors observed in Swiss mice were irrelevant for human risk assessment. They concluded the findings in the study did not provide justification to change the previous safety evaluations of aspartame in the European Union.
European Food Safety Authority (EFSA) Found No Link with Cancer
In addition to these specific investigations of published studies that have raised questions about the safety of aspartame, the European Parliament and Council on Food Additives requires all food additives under the purview of the EFSA to be re-evaluated whenever necessary due to changing conditions of use and new scientific information. Based on this requirement, the EFSA conducted a re-evaluation of aspartame (E 951) as a food additive in 2013 and published its most current Scientific Opinion. It said, in part, that hundreds of safety studies have been carried out on aspartame and in none other than the ERF studies were any associations with genotoxicity or cancer reported. It further concluded there was:
- no indication of a genotoxic concern in humans from aspartame based on the available data
- no evidence of treatment-related neoplastic or non-neoplastic lesions in any of the studies
- no increase in any type of neoplasms related to aspartame
- no epidemiological evidence for possible associations of aspartame with various cancers in the human population
Aspartame was independently reviewed two years later by Kirkland and Gatehouse. They stated their purpose was to critically review all the available genotoxic data on aspartame since Magnuson et al. (2007) only briefly covered that data. In this more thorough evaluation of in vitro and in vivo studies that included bacterial mutagenicity, chromosomal aberrations, micronucleus tests, DNA damage assays and germ cell data the authors supported the conclusions reached by the EFSA in its 2011 Scientific Opinion on genotoxicity testing strategies applicable to food and feed safety assessment that aspartame is non-genotoxic.
Exaggerated Levels Used in Studies Not Applicable to Typical Consumption
A Special Article on the biological fate of low-calorie sweeteners by Magnuson et al. (2016), and funded by an unrestricted grant from the Calorie Control Council, includes a discussion of how the actual exposure to these sweeteners has been overestimated and may contribute to fears about their safety.
This misperception is due, in part, to the fact low-calorie sweeteners are many times sweeter than sugar, so the products on the market typically contain 97%-99% filler and only 1%-3% of the actual sweetening ingredient. What may appear as a large dose to consumers represents an infinitesimal amount of the sweetener. For example, aspartame is 200 times sweeter than sugar so only 1/200th of the amount of sugar normally used in a food or beverage is needed to achieve the same level of sweetness. Since it would be nearly impossible to measure 1/200th of a teaspoon or a cup of sweetener, fillers are added to make measuring easier. The ease of measurement is particularly relevant when considering the substitution of aspartame for caloric sweeteners such as sucrose.
Consumers with lingering questions about artificial sweeteners and cancer can be reassured about its safety by reading the fact sheet on Artificial Sweeteners and Cancer published by the National Cancer Institute. It states there is no clear evidence of an association between artificial sweeteners and cancer in humans and does not include artificial sweeteners on its list of possible risk factors for cancer.