WHO Declares Aspartame a Possible Carcinogen

The World Health Organization’s cancer research agency, the International Agency for Research on Cancer, announced on July 14, 2023, that the common and popular artificial sweetener, aspartame, is a possible carcinogen. The classification of “possible carcinogen,” a class 2b, means the sweetener possibly causes cancer. Class 1 means an item can cause cancer; class 2a means it probably can, and class 3 means there is no cancer risk.

Despite the new designation by the IARC for aspartame, the Food and Drug Administration (FDA) stated on July 14, 2023, that it “disagrees with IARC’s conclusion” that the studies they evaluated “support classifying aspartame as a possible carcinogen to humans.” The FDA maintains that the IARC’s review has “significant shortcomings in the studies on which IARC relied.”

The FDA also noted that WHO and many other countries consider aspartame to be safe “at current permitted use levels.” Those levels (Acceptable Daily Intake, or ADI) is 40 milligrams/kilogram of body weight, approved by Health Canada and the European Food Safety Authority.

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To put it into perspective, an adult weighing 184 pounds (83 kilograms) would reach that limit when consuming about 33 cans of a diet soft drink in one day. In the US, individuals could drink even more diet soft drinks (40 cans) to reach the limit, as the ADI is even greater: 50 milligrams/kilogram of body weight.

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What is aspartame?

This artificial sweetener, which was approved by the US Food and Drug Administration in 1981, is known in scientific circles as L-aspartyl-L-phenylalanine methyl ester. It is composed of two amino acids, aspartic acid and phenylalanine, and is about 200 times sweeter than table sugar. It is used in many diet beverages, no- and low-calorie gums and candies, low-calories ice cream and other desserts, and other food items. Aspartame is also available in packets to be used in coffee, tea, and is added to foods such as cereals and smoothies.

How harmful is aspartame?

Studies over the past decades have found aspartame to be a health concern in animal and human studies. In a 2021 study entitled “Aspartame and cancer—new evidence for causation,” the authors conducted an immunohistochemical and morphological re-evaluation of original animal research and aspartame. Their findings confirmed that aspartame is a carcinogen in rodents and that prenatal exposure to the chemical increases cancer risk in rodent offspring. The authors “encourage all national and international public health agencies to urgently reexamine their assessments of aspartame’s health risks” and for “food agencies to reassess Acceptable Daily Intake” levels for aspartame.

In a later study, nearly 103,000 individuals participated in an analysis of their use of artificial sweeteners. The authors found that compared with nonconsumers, those who had higher intake of artificial sweeteners (especially aspartame and acesulfame-K) had a greater risk of overall cancer. Higher risks were seen for breast cancer and obesity-related cancers.

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Homer Swei, the Environmental Working Group’s senior vice president, Healthy Living Science, stated that “For years we’ve known that artificial sweeteners like aspartame are harmful to human health,” noting a rise in type 2 diabetes and obesity as well as a greater risk of cardiovascular disease. “We suspected aspartame might be a carcinogen as well, but this determination unequivocally solidifies that concern.” He emphasized that the FDA “should take seriously these latest troubling findings, which could put consumers, particularly children, at greater risk of cancer.”

According to Dr. Francesco Branca, director of WHO’s Department of Nutrition and Food Safety and who was part of the team that performed risk evaluation of aspartame, consumers have three choices when it comes to choosing sodas. They can select one with sugar, one with artificial sweeteners, or reach for water. He emphasized that it’s important for everyone to limit the amount of sweet beverages and foods they consume, regardless of whether they contain real or artificial sugar.

Bottom line

For years, some experts have noted that aspartame is associated with significant health risks. The new designation of possible carcinogen for aspartame by WHO’s International Agency for Research on Cancer has not changed the consumption guidelines but it has highlighted the health concerns noted with use of this artificial sweetener. As noted by Dr. Thomas Galligan, principal scientist for food additives and supplements with the Center for Science in the Public Interest, the declaration by WHO should “raise alarm bells for consumers.”

Aspartame. European Food Safety Authority 2023 Jun 28
Aspartame. Health Canada
Aspartame and other sweeteners in food. Food and Drug Administration 2023 Jul 14
Aspartame hazard and risk assessment results released. World Health Organization 2023 Jul 14
Christensen J. WHO declares widely used sweetener aspartame a possible cancer cause, but intake guidelines stay the same. CNN 2023 Jul 14
Debras C et al. Artificial sweeteners and cancer risk: Results from the NutriNet-Santé population-based cohort study. PLoS Medicine 2022 Mar 24; 19(3):e1003950.
Landrigan PJ, Straif K. Aspartame and cancer – new evidence for causation. Environmental Health 2021 Apr 12; 20(1):42.
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Lisa Roth Collins is a Registered Holistic Nutritionist (RHN) and is the Marketing Manager at NaturallySavvy.com. She is passionate about health and wellness and tries her best to make healthier choices every day for herself and her family. Her journey to natural health was driven by her own struggles with digestive discomfort, depression, and anxiety. Lisa returned to school in 2014 to study nutrition at the Canadian School for Natural Nutrition. She threw herself into her studies so she could learn as much as she could to help herself feel better and thrive. Upon completing the program and being certified as an RHN, Lisa began her work at Naturally Savvy where she has been able to help so many people learn to make healthier choices for themselves. Through her work, she has connected with so many incredible people in the industry whether other authors, influencers, or brands. Plus, she is affectionately known as "Techie Spice" because of her ability to wrap her head around technology. Every day she gets up with a renewed sense of energy and ready to make a difference. You can read all of Lisa's content here. In her spare time, Lisa loves to try new recipes, make delicious and nourishing meals, and she is an avid reader. For more information about Lisa, check out her profile on here.