What is aspartame? The WHO cancer warning about ‘possibly carcinogenic’ sweetener explained, and what it’s in

Aspartame, an artificial sweetener used in a host of popular foods and beverages, is set to be declared a possible cancer-causing substance by the World Health Organisation (WHO).

The ingredient will be listed as “possibly carcinogenic to humans” from next month based on the findings of the WHO’s International Agency for Research on Cancer (IARC).

The sweetener is currently authorised for use globally by regulators who have reviewed all the available evidence.

What is aspartame?

Aspartame is an artificial sweetener that is approximately 200 times sweeter than sugar. It has been commonly used as a low-calorie substitute for sugar in food and drink since the 80s, as the quantity of aspartame needed to give something a sweet taste is negligible.

The sweetness of aspartame lasts longer than that of sugar, so it is often blended with other artificial sweeteners such as acesulfame potassium to produce an overall taste more similar to sugar.

It is a white, odourless powder and has the trade names NutraSweet, Equal and Canderel.

The European Food Safety Authority (EFSA) says: “In Europe, aspartame is authorised to be used as a food additive to sweeten a variety of foods and beverages such as drinks, desserts, sweets, dairy products, chewing gum, low-calorie and weight control products, and as a table-top sweetener.

“The sweetener and its breakdown products have been authorised for human consumption for many years following thorough safety assessments.”

In both the UK and the EU the presence of aspartame must be indicated on the label either by its name or its E number (E 951), like with all additives.

Which products is aspartame found in?

Some examples of popular products which contain aspartame include:

• light yogurt
• reduced sugar energy bars
• sugar-free fizzy drinks
• sugar-free ice cream
• low-calorie fruit juice
• sugar-free gum
• reduced sugar ketchup
• sugar-free salad dressing
• zero-sugar sweets

Some of the most popular products that include the sweetener are Diet Coke, Fanta Zero and Wrigley’s Extra chewing gum.

Could aspartame cause cancer?

The IARC is preparing to label aspartame “possibly carcinogenic to humans” based on “two sources with knowledge of the process”.

This would mean that there is some evidence linking aspartame to cancer, but that it is limited.

The IARC has two more serious categories, “probably carcinogenic to humans” and “carcinogenic to humans”.

Its safety review was conducted to assess whether or not aspartame is a potential hazard, based on all the published evidence, but does not take into account how much of a product a person can safely consume, according to reports.

That advice comes from a separate expert committee, by WHO and the Food and Agriculture Organisation (FAO), on food additives – Joint FAO/WHO Expert Committee on Food Additives (Jecfa) – which has also been reviewing aspartame use this year. Jecfa is due to announce its findings on 14 July.

Since 1981, Jecfa has advised that aspartame is safe to consume within accepted daily limits. In line with the guidance, an adult weighing 60kg (132 pounds) would have to drink between 12 and 36 cans of diet soda – depending on the amount of aspartame in the beverage – every day to be at risk of cancer.

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The IARC said in a statement: “The IARC has assessed the potential carcinogenic effect of aspartame (hazard identification).

“Following this, the joint FAO/WHO Expert Committee on Food Additives (Jecfa) will update its risk assessment exercise on aspartame, including the reviewing of the acceptable daily intake and dietary exposure assessment for aspartame.”

The International Sweeteners Association (ISA) said “no conclusions” could be drawn until both reports were released.

ISA secretary general Frances Hunt-Wood said: “IARC is not a food safety body. The World Health Organisation’s Joint FAO/WHO Expert Committee on Food Additives (Jecfa) is currently conducting a comprehensive food safety review of aspartame and no conclusions can be drawn until both reports 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.”

Responding to the report, Kate Loatman, executive director of the International Council of Beverages Associations, said: “While it appears the IARC is now prepared to concede that aspartame presents no more of a hazard to consumers than using aloe vera, public health authorities should be deeply concerned that this leaked opinion contradicts decades of high-quality scientific evidence and could needlessly mislead consumers into consuming more sugar rather than choosing safe no- and low-sugar options – all on the basis of low-quality studies.

“Even the IARC agrees it is not the appropriate authority to undertake risk assessment based on actual consumption and that it ‘does not make health recommendations’.

“We remain confident in the safety of aspartame given the overwhelming weight of scientific evidence and positive safety determinations by food safety authorities in more than 90 countries around the world.

“We, therefore, welcome the broader, more comprehensive food safety review underway by the WHO and the UN Food and Agriculture Organisation Joint Expert Committee on Food Additives.”