Aspartame and Cancer

Aspartame was approved by the Food and Drug Administration (FDA) and considered safe in 1981. Since then, there have been conflicting reports of aspartame’s safety, including concern over its link to cancer. While the FDA maintains that approved artificial sweeteners, including aspartame, do not cause cancer, studies on rats raised new concerns over the years while others seem to assure its safety.

close up of woman sweetening coffee

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What Is Aspartame?

Aspartame is a low-calorie artificial sweetener that can be used in place of sugar to sweeten:

  • Foods
  • Beverages
  • Dental products
  • Gum

It is about 200 times sweeter than table sugar (sucrose), so much less is needed to produce the same sweetness level. Aspartame consists of amino acids phenylalanine and aspartic acid, with a methyl group added to the phenylalanine to create a sweet taste.

It is not a carbohydrate (saccharide) like regular sugars. It’s generally used to reduce calories in foods to help manage weight or for those with diabetes to prevent blood sugar spikes.

Aspartame is not heat stable and loses its sweetness when heated. For this reason, it is not often used in baked goods or other cooked foods. Other sweeteners are sometimes combined with aspartame to create a taste that is more similar to table sugar. Popular brands of aspartame include:

  • Equal®
  • Sugar Twin®
  • Nutrasweet®

Who Should Not Consume Aspartame?

People with phenylketonuria (PKU) cannot metabolize phenylalanine—a component of aspartame—effectively. Those with this rare hereditary disease should limit their intake of phenylalanine from aspartame and any other source. 

Does Aspartame Cause Cancer?

There has been conflicting research on whether aspartame causes cancer.

The National Toxicology Program determined in 2005 that aspartame does not cause tumors in mice but concerns developed from conflicting research performed on rats in 2006. The tests on rats suggested a link between aspartame and the development of lymphoma and leukemia. The FDA and others have scrutinized this research. 

Further research on humans has not shown a clear link between aspartame and cancer. In 2006, the National Cancer Institute revealed that its study on almost 500,000 men and women between the ages of 50 and 71 showed no connection between a higher level of aspartame intake and blood or brain cancers.

A 2013 meta-analysis in the Archives of Environmental and Occupational Health looked at the available research to date and determined that aspartame has no cancer-causing effect in rodents.

Weak Evidence

Several other studies have examined the link between aspartame and cancer, with most finding weak evidence of any connection.

For example, a 2012 study published in the American Journal of Clinical Nutrition claimed that women who drink diet soda every day have an increased risk of developing lymphoma and leukemia. However, the researchers apologized for promoting weak evidence and attempting to make the data fit the ideology rather than letting the science speak for itself.

Findings of Regulatory Agencies

The FDA reviewed the 2006 research on rats and determined it was not performed up to standard and did not change their position that aspartame is safe for human consumption. 

While the American Cancer Society does not determine if a substance is carcinogenic (causes cancer), it does rely on the FDA and other regulatory boards to decide on safety. The FDA says that even after over 100 studies, aspartame is safe for most people.  

The European Food Safety Authority (EFSA) says that aspartame has never been found in the blood or organs after ingestion. This finding means that aspartame is completely digested in the gut, absorbed by the body as amino acids and methanol, and is safe for consumption. Additionally, the EFSA states that there is no determinable link between cancer and aspartame when considering many human population studies.

A Word From Verywell

It can be challenging to know whether a substance like aspartame is safe for you to consume when presented with conflicting evidence. The evidence linking aspartame to cancer is weak, and there is an abundance of evidence that aspartame does not cause any type of cancer.

The FDA and EFSA state that aspartame is safe for human consumption. Talk to your healthcare provider if you are worried about your consumption of aspartame.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Additional information about high-intensity sweeteners permitted for use in food in the United States.

  2. Soffritti M, Belpoggi F, Degli Esposti D, Lambertini L, Tibaldi E, Rigano A. First experimental demonstration of the multipotential carcinogenic effects of aspartame administered in the feed to Sprague-Dawley rats. Environ Health Perspect. 2006;114(3):379-385. doi:10.1289/ehp.8711

  3. Lim U, Subar AF, Mouw T, Hartge P, Morton LM, Stolzenberg-Solomon R, Campbell D, Hollenbeck AR, Schatzkin A. Consumption of aspartame-containing beverages and incidence of hematopoietic and brain malignancies. Cancer Epidemiol Biomarkers Prev. 2006 Sep;15(9):1654-9. doi:10.1158/1055-9965.EPI-06-0203. PMID: 16985027.

  4. Mallikarjun, Sreekanth & Sieburth, Rebecca. (2013). Aspartame and Risk of Cancer: A Meta-analytic Review. Archives of environmental & occupational health. 70. 10.1080/19338244.2013.828674.

  5. Schernhammer ES, Bertrand KA, Birmann BM, Sampson L, Willett WC, Feskanich D. Consumption of artificial sweetener- and sugar-containing soda and risk of lymphoma and leukemia in men and women [published correction appears in Am J Clin Nutr. 2013 Aug;98(2):512]. Am J Clin Nutr. 2012;96(6):1419-1428. doi:10.3945/ajcn.111.030833

  6. American Council on Science and Health. Bad science from Harvard.

  7. American Cancer Society. Does aspartame cause cancer?

  8. European Food Safety Authority. Scientific opinion on aspartame.

By Rachel Macpherson
Rachel MacPherson is a health writer, certified personal trainer, and exercise nutrition coach based in Montreal.