WHO Classifies Sweetener Aspartame as 'Possible Carcinogen': Determining Safe Usage Levels

The World Health Organization (WHO) has categorized aspartame as a “possible carcinogen.”

The WHO cancer research arm, the International Agency for Research on Cancer (IARC) has declared the popular non-sugar sweetener possibly hazardous to people on the basis that there is limited evidence the substance is carcinogenic to humans.

A carcinogen is a substance that could potentially cause cancer.

The classification places aspartame in Group 2B, the third of the IARC’s four levels of carcinogen classifications.

The IARC noted that while the classification is something to consider, the acceptable daily intake (ADI) of aspartame is still 0–40 mg/kg of body weight.

Before coming to this decision, the IARC collected and screened more than 7,000 references and reviewed about 1,300 studies.

Aspartame was originally approved by the FDA in 1974, but it wasn’t approved as a general-purpose sweetener until 1996. Since approval, it’s been used as a tabletop sweetener, but also in beverages, prepared food, and chewing gum, as well as in medications like cough drops.

Aspartame is one of six approved artificial sweeteners in the United States and is about 200 times sweeter than sucrose (a natural sugar), Georgios Kyriazis, PhD, an assistant professor of biological chemistry and pharmacology for The Ohio State University College of Medicine told Health.

The sweetener has been controversial and under discussion since its approval by the Food and Drug Administration (FDA) in the 1970s, said Jagdish Khubchandani, PhD, a professor of public health at New Mexico State University.

“But numerous assessments since FDA approval have not shown solid evidence for cancerous effects,” Khubchandani said, including research conducted by WHO and the European Food Safety Authority.

The physical effects of aspartame can vary from person to person, Mona S. Jhaveri, PhD, a cancer researcher and founder of Music Beats Cancer, a funding platform for cancer research told Health.

“Reported symptoms have encompassed headaches, dizziness, digestive ailments, and allergic responses,” she said.

Of course, the symptoms you experience will depend on the amount you consume, explained Khubchandani.

“However, the first effects that you could see over time would clearly be related to metabolic abnormalities and weight gain before other organs (such as the liver) are affected,” he said. “Next could be high blood pressure and cholesterol.”

If you are concerned about consuming aspartame, Jhaveri suggests being aware of what you are eating and drinking. “It is prudent to scrutinize product labels for aspartame content when seeking to restrict or avoid its consumption.”

Classifying aspartame a possible carcinogen means that based on limited evidence, the sweetener could potentially cause cancer.

“The WHO has specific standards for classifying substances into different categories such as a possible carcinogen based on risk assessment,” Kyriazis said.

While some of the available limited research points to higher aspartame consumption contributing to a higher risk of cancer, it is often outside of the acceptable daily intake.

For the average consumer, the chances of aspartame causing cancer are likely very low, Kyriazis said. “If a diet coke or two a day was adequate to independently cause an increased risk for cancer, we would already know since aspartame and other artificial sweeteners have been in our diets for decades.”

Since its approval by FDA, aspartame has been investigated and debated for its cancer-causing potential, said Khubchandani. “But most studies have limitations and that could be the reason why we have not labeled it as a definite carcinogen, but [instead] it floats in the area of being a potential carcinogen.”

In other words, having a diet soda every now and then likely won’t make a huge impact on your health.

“For anyone who follows a balanced diet and consumes aspartame sparsely or at low amounts—such as a couple of packets in the coffee or a diet soda with a meal—it may not matter,” Kyriazis said.

Khubchandani added that everything in excess is bad for you, so it is important to be judicious, especially because recent studies show that artificially sweetened beverages aren’t just a cancer risk but also can increase heart disease risk.

“However, this does not mean that everyone will be at risk. Ultimately, it depends on other factors as well like lifestyle, diet, environment, dose of aspartame, and more.”