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What you need to know about Aspartame

You may have seen or heard news items about Aspartame, an artificial sweetener, and wondered if it's something you need to be worried about. Our toxicology and nutrition experts answer the most commonly asked questions about Aspartame. 

Aspartame is a common artificial sweetener used as a substitute for sugar in many food and drink products. It’s been in the news because the World Health Organisation recently classified it as a possible cause of cancer based on their latest review of the available scientific evidence. Here's our experts answers to the most common questions people have been asking about Aspartame. 

Q: How many products is aspartame used in?
A: According to a BBC report from June 2023, aspartame is an ingredient in about 6,000 food products worldwide. You might see it listed as an artificial sweetener on products like fizzy diet drinks or chewing gum. It can also be used in other products like medicines. 

Q: My family and I regularly eat or drink products containing aspartame. Should we be worried?
A: With any food or drink you consume, there’s something called the Acceptable Daily Intake or ADI. Basically, that’s the amount of something you can safely consume every day for the rest of your life. For aspartame that’s 40 mg per kg of body weight. 

So, if you’re an adult who weighs 90 kg, you can consume about 3½ grams of aspartame a day safely. If you got this just from soft drinks that contained 300 mg of aspartame in every can, that works out at approximately 12 cans (or 4 litres) of soft drinks a day.

Q: And what about my children?
A: For children, we would always recommend that they only drink milk and water so it’s harder to give an estimate. Also, their body weight varies greatly depending on their age – they might also be getting aspartame from other foods. But by way of illustration, a small child would reach their ADI by drinking about five cans of diet drink a day, while for older children it’s almost nine cans a day. 

Q: How can I avoid products with aspartame?
A: Aspartame is an artificial sweetener used as a sugar substitute. Check the label of any food product to see if it's listed as an ingredient. 

Q: What about other artificial sweeteners? 
A: Just because one food additive is categorised in this way, this doesn’t mean that other food additives get classified automatically.

Q: How much aspartame do I have to eat in order for me to be worried?
A: The toxicity of aspartame was reviewed and while experts have changed its classification to a possible cause of cancer, no evidence was found to justify lowering the recommended maximum intake level of aspartame. The Acceptable Daily Intake (ADI) - the amount you can safely eat every day for the rest of your life - is 40 mg/kg of body weight for an adult. 

Q: Will the food industry be asked to remove aspartame from their products?
A: That’s a matter for food regulators but we don’t expect it will be as the ADI hasn’t changed.

Q: What type of cancers does it cause?
A: To be clear, a direct causative link between aspartame and cancer has not been shown. The classification was based on ‘limited evidence’ for liver cancer from three human studies. The WHO also looked at breast and blood cancers in people, but the results were inconsistent. One study in animals suggested a carcinogenic effect but this study was not well run.

Q: Why are they coming out now and saying aspartame is carcinogenic?
A: The International Agency for Research on Cancer (IARC) is an agency within the World Health Organisation that promotes and coordinates research into cancer around the world. They reviewed about 1,300 studies on aspartame, some of which looked at its carcinogenicity (its cancer-causing effect). As a result Aspartame has been upgraded to a Group 2B carcinogen. 

Q: How do scientists come to a conclusion about the carcinogenicity of a chemical or additive?
A: The IARC experts review the scientific, chemical and medical data available on the chemical, and also how people are exposed to it. Their classification describes the potential for a chemical to cause cancer, not the likelihood of it doing so. 

In other words, they deal with the hazard and not the risk. The risk work is evaluated by another agency called JECFA, which is the ‘Joint FAO/WHO Expert Committee on Food Additives’. This is an international expert scientific committee that is administered jointly by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO).

Q: What does a ‘Group 2B Classification’ mean?
Based on the evidence, IARC has four classifications when it comes to carcinogenicity:

  • Group 1 means the chemical can cause cancer in people.
  • Group 2A means the chemical probably could cause cancer in people based on some evidence in human and animal studies.
  • Group 2B means the chemical could possibly cause cancer in people based on either some evidence of carcinogenicity in people OR good evidence for carcinogenicity in laboratory animals OR the chemical is similar in structure to other chemicals known to cause cancer in people.
  • Group 3 means a chemical can’t be classified for its carcinogenicity in people because there just isn’t enough evidence from either human, animal or chemical studies.

IARC currently classifies 322 other chemicals and agents to which people are exposed as ‘possibly carcinogenic to humans’ (Group 2B). This list includes ‘whole leaf extract of aloe vera’, carpentry, lead, bracken ferns and gasoline.

Q: How recent are the 1300 studies they reviewed? Wasn’t it reviewed before?
A: This is the first time that IARC reviewed aspartame. JECFA have reviewed it three times now and the most recent EFSA review was 2013.

Aspartame - an artificial sweetener used as a sugar substitute.
ADI - Acceptable Daily Intake; the amount you can safely eat every day for the rest of your life.
Carcinogen - a substance capable of causing cancer in living tissue.
EFSA – European Food Safety Authority
JECFA - the Joint FAO/WHO Expert Committee on Food Additives
IARC – International Agency for Research on Cancer; an agency within the World Health Organisation
WHO – the World Health Organisation


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