There has been widespread media concern on the link between artificial sweeteners and cancer. Here we break down the evidence behind the headlines and what has been recommended.
First of all, what are artificial sweeteners? Artificial sweeteners are used to provide a sweet taste to food and drinks in the place of sugar (sucrose). They are commonly found in no added sugar soft drinks, energy drinks, confectionary, frozen desserts, chewing gum, sweetened yoghurts or as table-top sweeteners. Artificial sweeteners contain less or no calories than sugar and can be up to 600 times sweeter than sugar, therefore are used in very small quantities.
Artificial sweeteners are also known as non-sugar sweeteners, non-nutritive sweeteners or no/low calorie sweeteners.
There are eleven types of artificial sweeteners licenced for use in the UK, with the most commonly known being aspartame, saccharin, sucralose and acesulfame K (ace-K).
Are they safe for consumption?
In the EU, rigorous safety tests are conducted on all artificial sweeteners used in food and drinks before approval by the European Commission.  There are Acceptable Daily Intake (ADI) levels set for each sweetener. For example:
The ADI for aspartame is 40mg/kg body weight per day. For a 70kg adult, the ADI would be 40x70=2800mg per day.
A UK Diet Coke contains 200mg aspartame.
For a 70kg adult, 2800/200=14. Therefore, the ADI for aspartame is ~14 cans of diet coke for a 70kg adult!
Studies have shown the average intake of sweeteners in the EU to be below the ADI, even amongst high consumers. Note, as one may consume aspartame/sweeteners from different sources, this would contribute to the daily intake!
Artificial sweeteners are safe for human consumption - with two exceptions:
Artificial sweeteners are not permitted for use in foods for infants and young children under the age of 3 years. Young children require energy-dense, nutritious food for optimal growth and development, hence sweeteners are not be suitable.
Individuals with a rare genetic condition called phenylketonuria (PKU), whereby break down of the amino acid phenylalanine is inhibited, should not consume aspartame. Products containing aspartame are labelled on the back of the packet.
Do they increase the risk of cancer?
In July 2023, the International Agency for Research on Cancer (IARC) ruled aspartame as “possibly carcinogenic to humans”.  This classification means there is limited evidence in humans and less than sufficient evidence in animals. Other products which have been ruled as possibly carcinogenic are aloe vera extract, engine exhaust, Asian pickled vegetables and occupational exposure as a hair dresser or barber.
There is some evidence that artificial sweeteners, mostly saccharin, increase the odds of bladder cancer. However, this evidence has been concluded as very low certainty due to poor quality of studies.
Therefore, there is no strong evidence in humans that sweeteners cause cancer.
Do sweeteners help with weight management?
In an updated review of the latest research, in May 2023 the World Health Organisation (WHO) recommended against the use of artificial sweeteners to control body weight or to reduce the risk of non-communicable diseases (i.e., Type 2 diabetes, cardiovascular disease...). 
Long-term studies have shown no long-term benefit of sweeteners in reducing body fat in children or adults.
There are also potential undesirable effects from long-term use, such as increased risk of Type 2 diabetes, CVD and mortality in adults.
This recommendation applies to all individuals, except those with pre-existing diabetes.
Artificial sweeteners are safe to consume (within ADIs) as a part of a healthy balanced diet, though are not advised for children under the age of 3 years.
There is no strong evidence in humans that aspartame, or any other artificial sweetener, causes cancer.
Sweeteners should not be used as a tool for weight management as long-term studies show no benefit. Individuals should consider other ways to reduce intake of free sugars, such as:
Drinking water vs sugar-sweetened drinks
Eating food with naturally occurring sugars, i.e, fruit, or unsweetened food and drinks.
EFSA. Artificial sweeteners. www.efsa.europa.eu/en/topics/topic/sweeteners. Accessed 19/07/2023.
World Health Organisation. Aspartame hazard and risk assessment results released. https://www.who.int/news/item/14-07-2023-aspartame-hazard-and-risk-assessment-results-released. Accessed 19/07/2023.
Use of non-sugar sweeteners: WHO guideline. Geneva: World Health Organization; 2023. https://www.who.int/publications/i/item/9789240073616. Accessed 19/07/2023.