Health Debunked: Do Artificial Sweeteners Like Aspartame Cause Cancer?

If you’ve been trying to lower your sugar intake, you may be consuming more sugar substitutes like artificial sweeteners. Artificial sweeteners — like aspartame, sucralose, and saccharin — have become more popular in recent years due to the appeal of cutting calories and eating less sugar to improve health.

But what about the decades-old claims that these sweeteners can cause cancer and the International Agency for Research on Cancer (IARC) labeling aspartame a possible carcinogen? We’ll dive into the science behind this claim. 

What is aspartame? 

Aspartame is a type of food additive and sugar substitute. It is considered an artificial sweetener. Aspartame is made in a lab by chemically combining different molecules. Like other artificial sweeteners, aspartame mimics the flavor of sugar. Yet it can be hundreds of times as sweet. 

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The digestive system doesn’t break down artificial sweeteners. And these sweeteners don’t provide you with any calories (energy).  

Are there other types of artificial sweeteners?

Yes. Besides aspartame, there are several other FDA-approved artificial sweeteners. These include:

• Saccharin

• Sucralose

• Acesulfame potassium

• Neotame

• Advantame

Why do people think aspartame and other artificial sweeteners cause cancer?

Concern about artificial sweeteners and cancer came about when an early study from the 1970s showed that saccharin appeared to cause bladder cancer in rats and mice. This led to many more studies, mostly in animals, on artificial sweeteners and cancer risk. 

For example, a 2005 study found a possibility that very high doses of aspartame might cause cancer in rats. And another study in 2016 reported a higher incidence of blood cell tumors in male mice that were fed high doses of sucralose. Because these sweeteners were found to cause cancer in rodents, many people believed they could in humans too. 

And in July 2023, an IARC statement stirred up concern after the World Health Organization-affiliated committee labeled aspartame a possible carcinogen. But scientists, the FDA, and other organizations were quick to point out that the evidence behind this allegation was limited and inconclusive, and they explained what this announcement actually meant for people. Let’s take a closer look.  

What does science say about aspartame and cancer?

Scientists have done many more studies on human consumption of aspartame. Research has shown no clear link between the use of artificial sweeteners and cancer risk when the sweeteners are consumed according to guidelines, which are still the same and recommend no more than:  

• 50 mg of aspartame for every kg of body weight, according to the FDA. For someone who weighs 60 kg (132 lb), this amounts to around 75 packets of aspartame or nine, 12-oz cans of diet soda per day.

• 40 mg of aspartame for every kg of body weight, according to the World Health Organization/Food and Agriculture Organization Joint Expert Committee on Food Additives (JECFA). Even with a slightly stricter recommendation, a person weighing 60 kg would have to consume around 64 packets of aspartame or eight, 12-oz cans of diet soda each day to reach the upper limit.

Nearly all of the studies linking artificial sweeteners to cancer were in rodents. And some of the ways cancerous tumors developed in rodents don’t apply to humans. For example, this is why saccharin was removed from the list of probable carcinogens in the U.S., despite it causing cancer in rats.

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Similarly, aspartame is classified as a 2B carcinogen, or a possible cancer-causing chemical, which is the third-highest category after “definite” and “probable.” In other words, “possible” does not mean the risk to people is high. Rather, based on the available data and estimated amounts of aspartame people actually consume, the scientific community says there is likely no reason to worry.     

Here’s what some of the experts have said and stand by in spite of aspartame’s classification:

• National Cancer Institute: According to the National Cancer Institute, results from multiple studies evaluating whether artificial sweeteners cause cancer have not provided clear evidence that they do.

• U.S. Food and Drug Administration (FDA): The FDA states that aspartame is “one of the most exhaustively studied substances” in food today, with “more than 100 studies supporting its safety.”

• European Food Safety Authority (EFSA): The EFSA says that “studies do not suggest an increased risk associated with aspartame consumption for … a variety of cancers, including brain, lymphatic, and haematopoietic (blood) cancers.”

• IARC and JECFA: Both WHO committees released a joint press release in which they “concluded that the evidence of an association between aspartame consumption and cancer in humans is not convincing.” 

Despite this, scientists agree that the relationship between artificial sweeteners and cancer should be further researched and that aspartame should be consumed in moderation.

What are the risks of artificial sweeteners like aspartame?

It’s not clear. Even though artificial sweeteners aren’t linked to cancer, it’s possible that they could affect your health in other ways. 

There’s some evidence that artificial sweeteners like aspartame, sucralose, and saccharin may be connected to:

• Increased appetite, hunger, and sugar cravings

• Weight gain

• Blood sugar problems

• Gut microbiome problems

• Stroke

• Heart disease

• Metabolic syndrome

Why trust our experts?

Written by:

Joanna Foley, RD

Joanna Foley, RD, is a registered dietitian (RD) and the owner of joannafoleynutrition.com, a private nutrition consulting business. She has previously worked as a clinical dietitian and outpatient renal dietitian.

Edited by:

Samvida Patel, MNSP, INHC

Samvida Patel, MNSP, INHC, is a health editor at GoodRx. She is a nutritionist and integrative nutrition health coach with over 8 years of experience in health communications.

Reviewed by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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