Aspartame is classed as a ’possible cancer risk’. What does this mean for sales of leading soft drinks?

What do aloe vera, the Korean pickled cabbage dish kimchi, talcum powder and the artificial sweetener aspartame have in common? They all pose a “possible cancer risk to humans,” according to the WHO’s International Agency for Research on Cancer (IARC).

Aspartame became the latest addition to the IARC’s 2B list of “possible carcinogens” on Friday, prompting the body to call for fresh research into the risks. So, what does all this mean for aspartame and the manufacturers that use it?

The first thing to note is consumption of aspartame is still deemed safe, so long as it does not exceed 40mg per kilo of bodyweight. For an adult weighing 70kg, that equates to between nine and 14 cans of sugar-free cola a day.

Indeed, bacon, ham and red meat are deemed more hazardous than aspartame by the IARC. In 2015, the body added processed meat to its group 1 list of carcinogens alongside alcohol, tobacco, arsenic and asbestos. Red meat went into group 2A, meaning it’s a “probable carcinogen”. So the 2B group for aspartame is not that serious by comparison.

In light of the findings, the WHO and the UN’s Food & Agriculture Organization’s Joint Expert Committee on Food Additives (JECFA), which assesses risk, reaffirmed its view that aspartame is safe at current permitted use levels.

The fairly low level of risk was highlighted in a statement from Dr Francesco Branca, director of the Department of Nutrition & Food Safety at the WHO. He stressed safety “is not a major concern at the doses which are commonly used”.

UK’s FSA backs the aspartame findings, with a caveat

However, there is a caveat. “Potential effects have been described that need to be investigated by more and better studies,” Branca added.

The ruling has provoked a mixed reaction. Professor Erik Millstone, one of the authors of arguably the most damning study on aspartame to date, is glad to see closer inspection of the ingredient. His study concluded aspartame’s safety had not been “adequately proven” and called for a suspension of its use.


“The IARC’s judgement is entirely sensible,” he says. “The IARC comprises only people with no conflicts of interest and looks purely at cancer risk. JECFA takes a broader view and has historically included paid consultants from the food industry and regulators. Effectively, they’re marking their employers’ homework. It’s not surprising they’ve given aspartame the benefit of the doubt.”

Meanwhile, the FSA has backed the findings, but pointed out the IARC is not a food safety agency. That point is similarly made by the International Council of Beverages Associations and International Sweeteners Association.

Some fear there will be unintended consequences. “Since IARC only looks at hazard potential and not risk, it does not paint a full picture of the safety of an ingredient, like aspartame, and can cause unnecessary public confusion,” said Dr Susan Elmore, who participated as an observer in the IARC aspartame review. “Aspartame has been deemed safe at real-world exposure levels by more than 100 human, animal, and mechanistic studies, and the vast majority of human epidemiology studies have provided no indication that consumption of aspartame induces cancer.”

Prominent media coverage could well influence the level of public reaction. When The IARC’s intention to list aspartame as a 2B cancer risk was first reported by Reuters in June, the national media dedicated plenty of column inches to the story.

Similarly negative coverage appeared just one month earlier, when the WHO advised against using sweeteners such as aspartame, acesulfame-K and sucralose for weight control and linked their long-term use to type 2 diabetes, heart disease and early death.

It’s a clear threat to sales of sugar-free drinks, in particular, many of which use aspartame. Until now, they have been reaping the benefits of the sugar levy. Sales of Coke Zero Sugar have surged by 153.9% to hit £366.3m since the tax was introduced in 2018. Meanwhile, Pepsi Max is up 107.9% to £599.8m and Red Bull’s sugar-free lines have grown by 115.1% to hit £96.7m in the past year [The Grocer Britain’s Biggest Brands 2018 v 2023].

Soft drinks makers likely to feel impact

If the IARC ruling on meat is anything to go by, that momentum could slow. When the body announced processed meat was “probably carcinogenic” – a higher risk than aspartame – sales in the UK of pre-packed sausages and bacon fell by a tenth in the following two weeks.

The major soft drinks manufacturers have so far been tight-lipped on the impact, but Liam Keogh, co-founder of Palm PR, admits this “could affect a lot of UK businesses”.

For some, like seltzer brand Dash, it could prove a gift. Co-founder and CEO Alex Wright says sales of its drinks, which contain no artificial sweeteners, are doubling every year. He believes people will gradually move away from aspartame-containing lines. “It’s not going to happen overnight, but soon Coke and other soft drinks brands will have to change because people are starting to vote with their wallets and change their behaviour,” he says.

On the flip side, brands like Oppo fear the negative impact. The low-calorie ice cream maker uses stevia and sugar alcohols, rather than aspartame. But as co-founder Harry Thuillier points out, the May announcement from WHO had all non-sugar sweeteners (NSS) in its sights.

Indeed, WHO’s Dr Branca made a damning statement on their usage in May. “People need to consider other ways to reduce free sugars intake, such as consuming food with naturally occurring sugars, like fruit, or unsweetened food and beverages,” he said. “NSS are not essential dietary factors and have no nutritional value. People should reduce the sweetness of the diet altogether, starting early in life, to improve their health.”

The question is what consumers will turn to when they inevitably do look for that hit of sweetness. And whether the headlines over aspartame will prove more powerful than the well-proven link between sugar and obesity.