What is it?
Acesulfame potassium, also called acesulfame K or Ace-K, is a man-made sweetener with no calories.
E-numbers / Sweeteners / E950
Acesulfame K
also: Acesulfame potassium · Ace-K · Sunett · Sweet One
A sweetener 200 times sweeter than sugar, usually paired with others in diet drinks. Reviewers flagged a manufacturing impurity in 2025.
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Carbonated Water, Citric Acid, Flavourings, Acidity Regulator (Sodium Citrates), Sweeteners (Acesulfame K, Sucralose), Preservative (Potassium Sorbate)
E950
Acesulfame K
A trace impurity from manufacturing, 5-chloro-acesulfame, was flagged by European reviewers in 2025 as possibly damaging DNA.
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UK supermarket foods that declare E950: 1,182 of the 43,325 we checked (2.7%)
Counted by its code or its name in the ingredient list.
Only 0.8% of these labels print “E950”. Most use the name: look for “acesulfame k”.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
How common it is in UK food, by aisle
- Soft drinks and juices782 products30% of 2,627
- Fruit, vegetables and salad93 products3.5% of 2,631
- Yoghurt, milk and dairy77 products3.4% of 2,273
- Chocolate and sweets76 products3.7% of 2,045
What Acesulfame K is, what it does and where you will see it
Why it’s worth knowing. A trace impurity from manufacturing, 5-chloro-acesulfame, was flagged by European reviewers in 2025 as possibly damaging DNA. Animal studies and small human trials suggest regular intake may change gut bacteria, though the human evidence is limited.
What does it do?
It triggers the sweet taste receptors on the tongue in very small amounts, so it tastes sweet without adding calories or carbohydrate. It survives heat and dissolves easily in water, so it works in baking and hot drinks. It has a slightly bitter aftertaste, which is why it is usually blended with other sweeteners.
Where you will see it
Diet fizzy drinks, flavoured waters, chewing gum, sugar-free sweets, low-calorie yoghurts, protein shakes, sweetener tablets, reduced-sugar baking and some flavoured medicines. It is often paired with aspartame or sucralose. Labels call it acesulfame K, acesulfame potassium or E950.
What the science says
An impurity from manufacturing may damage DNA
In their 2025 review, European reviewers found a possible DNA-damage risk from a trace impurity, 5-chloro-acesulfame, that can be present in the sweetener as made. They recommended either a strict limit of 0.1mg per kg for the impurity in the sweetener, or dedicated tests to settle the question.
Reviewers flagged a DNA-damage concern for the impurity 5-chloro-acesulfame, and recommended limiting it to 0.1mg per kg in the sweetener or requiring more data.
2025Regulator reviewEFSA Panel on Food Additives and Flavourings (FAF), re-evaluation of acesulfame K (E 950) as a food additive, EFSA Journal
It may change gut bacteria
Several animal studies, and a small number of short human studies, have found that regular acesulfame K changes the mix of gut bacteria. In mice, it changed the bacteria and body weight. In people, a diet drink containing it changed which bacterial species were present.
Mice given acesulfame K for 11 weeks had changed gut bacteria and gained more weight than controls.
2017Animal studyBian et al., PLOS ONE, PMC5464538
Drinking diet soda containing acesulfame K and sucralose changed the relative numbers of gut bacterial species in people.
2023ObservationalConsumption of sucralose- and acesulfame-potassium-containing diet soda alters the relative abundance of microbial taxa at the species level, Applied Physiology Nutrition and Metabolism
In rats, acesulfame K and saccharin changed the gut bacteria and their chemical output, with fewer of some helpful species.
2022Animal studyInvestigating the gut microbiome and metabolome following treatment with artificial sweeteners acesulfame potassium and saccharin in young adult Wistar rats, Food and Chemical Toxicology
A higher daily limit in 2025
The 2025 review raised the daily limit from 9mg to 15mg per kg of body weight, after re-analysing the existing studies rather than new ones.
Reviewers raised the daily limit for acesulfame K to 15mg per kg of body weight in 2025, from 9mg per kg set in 2000, after re-analysing the key studies.
2025Regulator reviewEFSA Panel on Food Additives and Flavourings (FAF), re-evaluation of acesulfame K (E 950) as a food additive, EFSA Journal
Where it stands with the regulators
Approved in the UK and the EU
Daily limit. 15mg per kg of body weight a day (European reviewers, 2025, up from 9mg).
- Legal basis
- On the Food Standards Agency's approved list for Great Britain. European reviewers completed a full review in 2025.
- Permitted foods
- Reduced-energy or no-added-sugar soft drinks · Flavoured waters · Chewing gum · Sweets · Desserts · Breakfast cereals · Sweetener tablets · Flavoured yoghurts · Reduced-energy or no-added-sugar baking · Some medicines
- Maximum levels
- Set for each type of food, for example 350mg per litre in soft drinks.
- History
- Acesulfame K was first approved in the EU under the 1994 sweeteners directive. The EU's Scientific Committee on Food set a daily limit of 9mg per kg in 2000. European reviewers completed a full review in 2025, raised the limit to 15mg per kg, and flagged the impurity 5-chloro-acesulfame, recommending the Commission tighten the purity rules. It remains allowed in the UK.
Who should be careful
People with phenylketonuria (PKU) should check labels: acesulfame K has no phenylalanine, but it is often blended with aspartame, which does. Anyone avoiding all artificial sweeteners should look for acesulfame K, acesulfame potassium or E950. People with kidney conditions may want to note it contains potassium.
The honest read
The 2025 European review flagged a possible DNA-damage issue with a trace impurity that can be in the manufactured ingredient. Whether makers consistently meet the recommended impurity limit is not publicly tracked. The gut bacteria findings are real signals.
Common questions about Acesulfame K
Is E950 banned in the UK?
No. Acesulfame K is approved in the UK. European reviewers looked at it again in 2025 and it remains allowed.
What did the 2025 review find?
It flagged a possible DNA-damage risk from a manufacturing impurity, 5-chloro-acesulfame. Reviewers recommended limiting it to 0.1mg per kg in the sweetener, or more testing to settle the question.
What foods contain E950?
Diet fizzy drinks, flavoured waters, sugar-free chewing gum, low-calorie sweets, protein bars and shakes, reduced-sugar yoghurts, sweetener tablets and some flavoured medicines. It is often combined with aspartame or sucralose.
Is E950 vegan?
Yes. It is made in a factory from chemicals, with nothing from animals.
Sources
- EFSA re-evaluation of acesulfame K (E 950) as food additive (PubMed abstract)
- UK FSA Approved additives and E numbers
- Bian et al. The artificial sweetener acesulfame potassium affects the gut microbiome and body weight gain in CD-1 mice (PMC5464538)
- Consumption of sucralose- and acesulfame-potassium-containing diet soda alters the relative abundance of microbial taxa at the species level, Applied Physiology Nutrition and Metabolism (2023)
- Investigating the gut microbiome and metabolome following treatment with artificial sweeteners acesulfame potassium and saccharin in young adult Wistar rats, Food and Chemical Toxicology (2022)
- Non/Low-Caloric Artificial Sweeteners and Gut Microbiome: From Perturbed Species to Mechanisms, PMC (2024)
Last reviewed: 9 November 2026
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