If you’re not a fan of Diet Coke yourself, you probably know someone who is. So the news that aspartame – one of the key ingredients in the popular fizzy drink – is set to be declared as “possibly carcinogenic” by the International Agency for Research on Cancer (IARC).

According to Reuters, the IARC, which is the cancer research arm of the World Health Organisation (WHO), is expected to make the announcement on 14 July. 

The ruling is said to be the verdict of a review of around 1,300 studies into the artificial sweetener – and has left many fans of Diet Coke and other sugar-free fizzy drinks wondering whether they need to cut their habit.

To help you get a clear perspective, we asked the experts to explain more about this decision and what the “possibly carcinogenic” label really means. Here’s what they had to say. 

While people are understandably alarmed by this label, it’s important to understand what this category means. To start off with, you should know that the IARC uses four possible classifications to measure carcinogenic properties:

• Group 1 – carcinogenic to humans
• Group 2A – probably carcinogenic to humans
• Group 2B – possibly carcinogenic to humans
• Group 3 – not classifiable

Plenty of substances and activities have been classified using this system. They include eating red meat (which was classified as 2A back in 2018), night shift work (which was classified as 2A back in 2020) and aloe vera (which was classified as 2B back in 2016). 

However, these groupings don’t necessarily tell us how big of a risk something poses – just how strong the evidence is. So, what does ‘possibly carcinogenic’ mean? 

“Aspartame being labelled as ‘possibly carcinogenic’ by the IARC means that there is limited evidence suggesting a potential association between aspartame and cancer risk,” explains Lee Mitchell, a nutritionist and UK fitness ambassador for the health and wellness brand Renpho.

The findings do not take into account how much of a product a person can safely consume – just that previous research has identified some kind of link between the sweetener and a higher risk of cancer.

“It is important to note that this classification does not indicate conclusive evidence of a direct link between aspartame and cancer – regulatory bodies such as the UK Food Standards Agency (FSA), the European Food Safety Authority (EFSA) and the US Food and Drug Administration (FDA) have extensively reviewed the safety of aspartame and concluded that it is safe for human consumption within the recommended daily limits.” 

More information on aspartame and its safety is expected in July, when the Joint World Health Organisation and Food and Agriculture Organisation’s Expert Committee on Food Additives is expected to release a report.

According to the BBC, since 1981 the organisation’s stance has been that a daily intake of 40mg per kilogram of your body weight per day was safe. For reference, a can of Diet Coke contains around 200mg of aspartame.

Sas Parsad, a nutritionist at The Gut Co, also believes the latest reports should be taken with a pinch of salt – and that more research is needed to understand the full extent of what’s going on.  

“The label suggests there is limited evidence linking aspartame to cancer, so we shouldn’t jump to conclusions yet,” he says. “Aspartame has been put in the same category as ‘using a mobile phone’ and I think we are all quite guilty of that.

“Fundamentally, it means the connection could be clearer, and more research is needed to understand the full picture, but it is something to have on our radar.”

In a statement, Frances Hunt-Wood, Secretary General of the International Sweeteners Association, said no conclusions could be drawn from the current information until all ongoing investigations are published.

“Aspartame is one of the most thoroughly researched ingredients in history, with over 90 food safety agencies across the globe declaring it is safe, including the European Food Safety Authority, which conducted the most comprehensive safety evaluation of aspartame to date,” she said.

At the end of the day, moderation is key – and no one can make decisions about your health except for you. All you really need to know is that, while a link between aspartame and a higher risk of developing cancer has been established, the current research proving that link is limited – and more information is needed to understand what’s actually going on. 

Images: Getty