Does Aspartame Cause Cancer? The Truth about Aspartame Sweetener

The International Agency for Research on Cancer (IARC), which forms part of the World Health Organization (WHO), has called aspartame sweetener a ‘possible carcinogen’. Carcinogen is a substance, organism or agent that’s capable of causing cancer.

In response to the headlines, social media has been awash with fear mongering and misinformation – it’s no wonder many are confused about whether they should ditch their diet drinks or not.

Due to the purported side effects of aspartame, its inclusion in foods and drinks has sparked much controversy over the years. In fact, it’s one of the most heavily studied food additives, with research papers dating back to over four decades ago.

So, we decided to take a look at the data and research papers on aspartame and deliver the facts, and only the facts.

Is aspartame bad for you? Well, we’re going to find out.

What Is Aspartame?

aspartame artificial sweetener molecule, illustration


Aspartame is one of the most commonly used sweeteners. It’s used by UK food and drink manufacturers in a variety of products like diet drinks, yoghurt and chewing gum. Aspartame is made of amino acids – aspartic acid and phenylalanine – which are found in proteins such as meat. Aspartame is calorie free and about 200 times sweeter than regular granulated sugar, but it is used in very small amounts so can often be included in moderation to achieve weight loss goals.

Is Aspartame Bad for You?

While the IARC called aspartame a ‘possible carcinogen’, it does not take into account the dosage. It’s also worth highlighting that the IARC isn’t a food safety agency.

The emphasis in their statement is on the word ‘possibly’, and it’s important to take note of. They use the wording ‘possibly causing cancer’ because there is not enough evidence to make the claim.

The European Food Safety Authority and JECFA, an international scientific expert committee administered jointly by the Food and Agriculture Organization of the United Nations (FAO) and WHO, have both stated aspartame is safe for human consumption. JECFA notes that ‘a 60kg adult would need 12-36 cans of diet soda every day to be at risk.

If you are thinking about ditching your diet drinks, it’s important to ask yourself if your current levels of consumption exceed 12 cans a day. It could be that you enjoy one can a day in moderation, which is an easy low-calorie swap for the high sugar version.

In a study published by the Nutrition Diary, it was concluded that soft drink intake increased blood pressure when compared with non caloric soft drinks. So, while we may have the best intentions when choosing non diet versions of drinks, there could be negative consequences of including the high sugar versions.

JEFCA is currently reviewing aspartame use and they are due to announce their findings on 14 July when the IARC makes its decision public. Whether their ’12-36 cans’ per 60kg recommendation for adults will change, we will see.

child holds out a glass as a man pours a carbonated beverage into it

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Does Aspartame Cause Cancer?

What is important to understand about interpreting studies, is that we are (unfortunately) not experts in scientific research. Some studies on aspartame, like the widely discredited example published by About Health Perspective on rats, have limitations when applied to humans. For example, we won’t have 200 times the dose of aspartame, and also, we’re not rodents. A study conducted by the The University of Maryland backs up this point, stating that it’s unlikely humans would be able to consume the high amount of aspartame used on the rats.

Further studies, like this one published in Critical Reviews of Toxicology, have cited that there’s no evidence to support an association between aspartame and cancer in any tissue. In the Journal of the National Cancer Institute, it states that their review revealed little biologic or experimental evidence that aspartame is likely to act as a human brain carcinogen.

Is Aspartame Safe?

Yes, aspartame is safe.

According to Safety Of Aspartame, there have been 100 studies, 200 scientists and 90 countries all saying the same thing. For over forty years, the FDA has repeatedly confirmed that aspartame is safe for human consumption.

The European Food Safety Authority states that: ‘[Aspartame] has been found to be safe and authorized for human consumption for many years and in many countries following thorough safety assessments.’

The FDA states that: ‘Aspartame is one of the most exhaustively studied substances in the human food supply, with more than 100 studies supporting its safety. FDA scientists have reviewed scientific data regarding the safety of aspartame in food and concluded that it is safe for the general population under certain conditions.’

This has also been confirmed by:

  • European Food Safety Authority
  • Health Canada
  • UK Food Standards Agency
  • Cancer Research UK
  • Food Standards Australia
  • And many other academic research institutions

The conclusion is that as long as you are consuming it in moderation and staying within recommendations, aspartame can be included safely. As with all information online, be your own expert, question misinformation and do what is right for your body.

Headshot of Kate Neudecker

Kate is a fitness writer for Men’s Health UK where she contributes regular workouts, training tips and nutrition guides. She has a post graduate diploma in Sports Performance Nutrition and before joining Men’s Health she was a nutritionist, fitness writer and personal trainer with over 5k hours coaching on the gym floor. Kate has a keen interest in volunteering for animal shelters and when she isn’t lifting weights in her garden, she can be found walking her rescue dog.

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