Aspartame and cancer

12th July 2023

You're almost certain to have heard about aspartame and its possible connection to cancer at some point in your life, and it's a particularly hot topic of conversation at the moment. But it can be difficult to know exactly what the facts are, so we asked our experts to provide the answers.

What is aspartame?

Aspartame is a sweetener that was discovered in the late 1960s and primarily studied in the 1970s. Commonly used as a sugar substitute, aspartame is 200 times sweeter than regular sugar.

Aspartame was introduced as a low-calorie alternative in 1981 and is now widely used in various food and drink products.

So widely in fact, that it can be hard to keep track of, so we asked Worldwide Cancer Research's Funding Administrator Laura Perez, who is also a qualified Dietitian, to outline the types of foods and drinks that are known to contain aspartame.

What contains aspartame?

  • Diet sodas and soft drinks: Many sugar-free or low-calorie beverages, including diet colas, flavoured water, and energy drinks, contain aspartame.
  • Sugar-free sweets and chewing gum: Aspartame is often used as a sugar substitute in various sugar-free sweets and gum products.
  • Yogurts and dairy desserts: Some flavoured yogurts and dairy-based desserts may contain aspartame to enhance sweetness without adding extra calories.
  • Tabletop sweeteners: Aspartame is available in powdered or granulated form as a tabletop sweetener.
  • Baked goods and desserts: Certain sugar-free or reduced-sugar baked goods, such as cookies, cakes, and puddings, may contain aspartame.
  • Breakfast cereals: Some cereals marketed as low-sugar or diet-friendly may include aspartame as a sweetening agent.
  • Ice creams and frozen desserts: Aspartame can be found in certain sugar-free or light ice creams, frozen yogurt, and other frozen treats.
  • Drink mixes and powdered beverages: Instant drink mixes, powdered fruit drinks, and protein powders sometimes use aspartame to add sweetness.

Is there a link between aspartame and cancer?

The International Agency for Research on Cancer (IARC), which is the cancer research arm of the World Health Organization (WHO),  conducted a safety assessment of aspartame in 2023.

After this assessment, they decided to label aspartame as "possibly carcinogenic to humans." This classification suggests that there is some evidence linking aspartame to cancer, although it is limited.

It is important to note that the IARC has two more severe categories, namely "probably carcinogenic to humans" and "carcinogenic to humans."

Should I be worried about consuming aspartame? 

The report from the International Agency for Research on Cancer (IARC) suggests that there is limited evidence linking aspartame to cancer, labelling it as "possibly carcinogenic to humans." However, it's important to note that this classification means the evidence is not strong enough to categorise it as a definite cancer-causing agent.

When it comes to the use of sweeteners it’s essential to evaluate the evidence and consider your individual circumstances to make an informed choice. For example, when consumed in moderation, sweeteners can often act as a "stepping stone" to help people reduce their overall intake of sugar, which carries its own health risks. 

In the future research might reveal more information, but the current evidence does not suggest that you should be overly worried about consuming aspartame in moderation.


Research is vital to help us better understand the key factors that affect our risk of developing cancer. Thanks to research funded by our Curestarters, Dr Tracy O'Mara in Australia discovered 5 key risk factors for endometrial cancer. This discovery could go on to help people at high risk from developing endometrial cancer, and could shed light on new ways to treat patients with the disease.

Five key risk factors for endometrial cancer that you should know about

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