Aspartame is a potential carcinogen: What does this mean for me?

Mixing sweetener into coffee.

What do soda, candy, sugar-free gum and low-fat yogurt all have in common? Sure, they’re all forms of food. But another common characteristic with certain brands may be an ingredient called aspartame.

Aspartame is an artificial sweetener that’s been used in the U.S. since the 1980s. It’s a lot sweeter than sugar, so smaller amounts can be included to provide the same level of sweetness.

Chances are high that you’ve consumed aspartame. For some people, it’s a staple in their favorite foods or beverages.

The safety of aspartame has been in question for several years. In early 2023, these concerns were strengthened when major health agencies, including the International Agency for Research on Cancer (IARC), the World Health Organization (WHO) and the Food and Agriculture Organization (FAO) Joint Expert Committee on Food Additives (JECFA), listed the artificial sweetener as "possibly carcinogenic to humans" — or possibly a cause of cancer.

While this news may be scary, don’t panic. Here’s what you need to know about aspartame’s recent categorization as potentially carcinogenic and what it means for your eating habits.

What is aspartame?

From candy to gum to soda, sweetened beverages and foods are a go-to treat for many. But some people don’t want the calories that come with real sugar, so they turn to products that contain aspartame.

"Aspartame is a non-nutritive sweetener, meaning it has a very small amount of or no carbohydrates," says Zonera A. Ali, MD an oncologist and hematologist at Main Line Health. "Unlike sugar, it doesn’t provide you with any energy. It’s also extremely sweet — about 200 times sweeter than sugar. As a result, only a tiny amount is needed to sweeten your favorite food or beverage."

Aspartame is found in many products, including chewing gum, gelatins, instant coffee, tea and dairy products. It’s also in diet sodas, like Diet Coke®, Coke Zero Sugar®, Mountain Dew Zero Sugar®, Sprite Zero Sugar® and Pepsi Zero Sugar®.

Does aspartame cause cancer?

"Concerns about aspartame and cancer date back to the late 2000s, when some studies in lab rats pointed to a connection between aspartame and certain blood-related cancers and other kinds of cancer," says Dr. Ali.

However, these studies were limited, making their validity hard to determine.

Researchers have since conducted studies in humans to see if they can find a similar connection, but findings haven’t been consistent.

In June 2023, the IARC — which is a part of the WHO and whose role it is to identify the causes of cancer — announced that aspartame could be a possible carcinogen (or cancer-causing ingredient) for humans.

The IARC put aspartame in category 2B, which is used when there is limited evidence a product causes cancer in humans and less than sufficient evidence it causes cancer in animals during experiments.

This category includes other possible carcinogens, like red meat and very hot drinks over 149 degrees Fahrenheit. It does not include known carcinogens, like tobacco and outdoor air pollution.

The question of whether or not aspartame causes cancer is not straightforward. While studies haven’t shown that it will cause cancer, this risk — among other health risks — are worth considering.

Are there any other health risks related to aspartame?

Outside of potential cancer risks, aspartame has been under scrutiny for other health concerns — namely migraines, depression, heart disease, diabetes, dementia and developmental issues.

However, several governmental agencies, including the Food and Agriculture Organization of the United Nations and the WHO — say there are no negative effects of aspartame as long as you don’t consume more than 40 milligrams per kilogram of body weight daily. In the U.S., the Food and Drug Administration (FDA) set its acceptable daily intake at 50 milligrams per kilogram of body weight.

For context, according to the WHO’s standards, a person who weighs 154 pounds shouldn’t have more than nine cans of Diet Coke a day. As for packets of Equal®, a person around the same weight would need to consume 75 packets per day.

Another concern surrounding aspartame is using it to limit calories to lose weight or avoid gaining weight. Some studies suggest that artificially sweetened products might actually cause you to crave other sweet, high-calorie foods.

Based on the evidence, the WHO recommends not using non-sugar sweeteners to limit calories and focusing on healthy eating habits instead.

Should I cut aspartame out of my diet?

The bottom line about aspartame, like many potentially unhealthy foods, is that moderation is key. Having a food or beverage sweetened with aspartame from time to time isn’t necessarily harmful, but consuming aspartame every day with every meal could cause long-term problems.

Instead, focus on eating a diet full of fresh foods, including fruits, vegetables, whole grains, lean meats and fat-free or low-fat milk and milk products. While it’s important to also limit sugars, don’t replace them with foods containing aspartame. If you crave sweet foods, consider options like fruit and yogurt, bananas and peanut butter or a smoothie.

Paying attention to the ingredients in what you eat and drink is a key part of maintaining your health. By making informed choices, you can lead a healthy life now and in the future.

Next steps:

Meet Zonera A. Ali, MD
Learn more about cancer care at Main Line Health
Community, guidance and hope: The importance of attending cancer support groups