Aspartame: What common foods contain the sweetener that possibly causes cancer?

Regulator says a 9-stone person would need to drink 12 to 36 cans of Diet Coke a day to see adverse affects from aspartame

Bottles of Diet Coke are seen on display at a market in New York City, New York, U.S., June 28, 2023. REUTERS/Mike Segar
Aspartame is found in soft drinks such as Diet Coke. (Reuters)

A sweetener used in Diet Coke and other sugar-free fizzy drinks may cause cancer, the World Health Organization (WHO) is reportedly set to announce.

Aspartame – which is listed in the ingredients of the popular soft drinks brand – is set to be listed by the WHO's International Agency for Research on Cancer (IARC) as “possibly carcinogenic to humans” from next month, according to the Reuters news agency.

Since 1981, the Joint US Food and Agriculture/WHO Expert Committee on Food Additives (JECFA) regulator has said aspartame is safe to consume within accepted daily limits, which depends on a person's bodyweight.

It estimates that a nine-stone person would need to drink 12 to 36 cans of Diet Coke a day to see adverse affects from aspartame.

Experts responding to the Reuters have urged people to wait for the IARC's final announcement, emphasising that possibly being carcinogenic does not mean that a substance actually presents a risk to humans in normal circumstances.

According to the American Academy of Family Physicians, aspartame is one of the most studied sweeteners in the world – with more than 100 studies carried out into the product.

While the WHO is to list it as potentially cancer-causing, aspartame has not been listed as carcinogenic by the US National Cancer Institute.

In the UK, aspartame is approved for use. According to the NHS: "There have been reports that the use of sweeteners is linked to other health issues but the evidence base for this is limited," while Cancer Research UK has maintained that sweeteners do not cause cancer.

The sweetener is also listed as having other potential side-effects, with one study from Massachusetts General Hospital in 2022 suggesting aspartame could contribute to weight gain, although the NHS says using sweeteners rather than sugar can aide weight control.

“Aspartame consumption needs to be approached with caution due to the possible effects on neurobehavioral health," the authors of a 2017 study in Nutritional Neuroscience said, suggesting the sweetener could cause cognitive and behavioural problems including anxiety, depression and insomnia.

But aspartame, which is also listed as E-number E951, isn't just in fizzy drinks – it can be found in a number of other foods people consume on a regular basis.

Colorful breakfast cereal with milk fills spoon in foreground with cereal in glass bowl on pink background in out-of-focus background
Aspartame can also be found in some breakfast cereals, as well as other foods and fizzy drinks. (Getty)

Here's where else you can find the artificial sweetener:

  • Breakfast cereals

  • Chewing gum

  • Chewable vitamins

  • Gelatin

  • Ice cream

  • Puddings

  • Tabletop sweeteners

  • Ice-cream toppings

  • Fruit spreads,

  • Low-fat yogurts

  • Mousses

Aspartame: What the experts say

Professor Kevin McConway, from the Open University, urged people to wait for the IARC's final announcement.

He also emphasised that possibly being carcinogenic does not mean that a substance actually presents a risk to humans in normal circumstances.

Caramel and chocolate indulgent extreme milkshakes with brezel waffles, popcorn, marshmallow, ice cream and whipped cream.
Ice cream and toppings often contain aspartame. (Getty)

He said: "The IARC experts do not assess whether, in practice, a substance or exposure presents a cancer risk to people. Instead they assess whether it would ever be capable of presenting a risk, under any circumstances, even if the only harmful circumstances are really, really unlikely to occur."

Professor Oliver Jones, professor of chemistry at RMIT University in Melbourne, Australia, said: “We really need to wait and see the full IARC evaluation before we can make any firm conclusions. Without that we are really shooting in the dark. We don’t know what the terms of the assessment were, or what criteria they used to rule evidence in or out.

“It is also important to note that just because something may possibly cause cancer does not mean that it automatically does if you are exposed to it. The dose makes the poison.

Professor Tom Sanders, professor emeritus of nutrition and dietetics at King’s College London, said: “As far as I am aware there is no evidence from human prospective studies linking aspartame use to cancer and regulatory authorities have extensively reviewed the toxicological data and given aspartame a clean bill of health.”

Yahoo News has contacted Coca-Cola for comment.