Artificial sweeteners and cancer: 7 things to know 

Artificial sweeteners have been on a lot of people’s minds lately — especially since the World Health Organization’s (WHO) International Agency for Research on Cancer (IARC) recently reclassified aspartame as a possible carcinogen, or substance that causes cancer.

But what does that change in status mean? Should we rethink which artificial sweetener to use in our daily coffee or iced tea? Or reconsider our use of artificial sweeteners altogether?

We checked in with Ernest Hawk, M.D., vice president and head of Cancer Prevention and Population Sciences at MD Anderson. Here’s what he wants people to know.

How does the WHO/IARC’s reclassification of aspartame affect the average person?

Not at all. It essentially changed aspartame’s status from “we don’t know if it causes cancer” to “it’s possible that it might cause cancer, but more research is necessary.” So, essentially, it’s a variation of “we don’t know.”

Should people stop using aspartame as a result of this announcement?

No. Acceptable levels of intake for aspartame were up to 40 milligrams per kilogram of body weight per day before the announcement, and those recommendations have not changed. Specifically, IARC’s recommendations related to aspartame intake limits did not change as a result of this reclassification.

So, what was the purpose of the reclassification announcement?

It was meant primarily as a call to action for scientists, I think.

The WHO’s reclassification of aspartame from its lowest level of risk (Group 3 – not classifiable as to its carcinogenicity to humans) to its Group 2B level (possibly carcinogenic to humans) indicates only that there is a clear need for further, high-quality research on non-sugar sweeteners and their possible long-term health implications. 

Are any artificial sweeteners currently classified as carcinogens?

No. Saccharin was placed on the list of cancer-causing chemicals by the Department of Health and Human Services (HHS) in the late 1970s or early 1980s. But it was the only one of the marketed non-sugar sweeteners, and that designation was based on flawed research, so the ruling was reversed by the year 2000. 

Is there any reason now that people should avoid using artificial sweeteners?

Well, they are non-nutritious. That is, they don’t offer anything of particular value other than their sweet taste. So, there’s no reason to use them other than for their taste. Artificial sweeteners may also increase your sugar cravings or tolerance for sweet things, which could lead you to consume more empty calories.

However, there are no compelling safety data that suggest any currently marketed non-sugar sweetener should be avoided in the amounts that are typically consumed. And, there is no new established hazard that should prompt a change in anyone’s use of these substances today, based on WHO’s most recent data analysis.

Is there anything cancer patients in particular should know about artificial sweeteners?

No. There’s no convincing evidence that either using or avoiding sugar and non-sugar sweeteners can adversely impact either cancer development or its responsiveness to treatment. 

Some people have suggested that cancer patients may benefit from limiting sugar or eliminating it from their diets. But the actual science and data underlying those suggestions remain weak. 

A much better recommendation is to limit the number of empty calories you consume each day, particularly when they come from added or processed sugars. We recommend adopting a healthy, nutrient-dense diet that is largely plant-based (2/3 of a plate containing fruits and vegetables) and incorporates mostly whole foods.  

What’s the one thing you want people to know about artificial sweeteners and cancer risk?

High body weight is much more strongly and convincingly linked to cancer risk in both human and animal studies than anything related to non-sugar sweeteners at this time. So, as of 2023, high body weight is a much more clear and present danger to our health. 

More high-quality research on artificial sweeteners’ and sugar’s impact on cancer development and outcomes is needed before strong dietary recommendations can be made regarding those dietary elements.

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