Cyclamate
An artificial sweetener, around 30-50 times sweeter than sugar, used in diet drinks, table-top sweeteners and reduced-sugar foods. Banned in the USA.
Cyclamate is broken down in the gut by some people into cyclohexylamine, a compound that caused testicular damage and reproductive harm in animal studies at high doses. The EU safety limit is set to keep exposure to cyclohexylamine below the level that caused harm in animals.
What is it?
Cyclamate is a synthetic non-nutritive sweetener. The E952 group covers cyclamic acid and its sodium and calcium salts. It has no calories and is typically 30 to 50 times sweeter than sugar, though the ratio varies with concentration and the food matrix. It is often blended with saccharin (E954) to mask each compound's aftertaste.
What does it do?
Cyclamate binds to sweet-taste receptors on the tongue and triggers a sweetness signal without providing calories or raising blood glucose. Unlike sugar, it is not metabolised for energy. A proportion of the population (around 30-40% of people, varying by gut microbiome composition) harbour bacteria that convert cyclamate into cyclohexylamine, which is absorbed and excreted in urine. This metabolic conversion is the basis of the key safety concern.
Where you will see it
Most commonly found in diet or reduced-calorie carbonated soft drinks, squashes, cordials, and fruit drinks. Also used in table-top sweetener tablets and sachets, sugar-free confectionery such as boiled sweets and chewing gum, reduced-sugar jams and preserves, and certain diabetic food products. On a label it appears as 'cyclamate', 'sodium cyclamate', 'calcium cyclamate', or 'E952'.
What the science says
Gut bacteria convert cyclamate into cyclohexylamine
Around 30-40% of people carry gut bacteria that convert cyclamate into cyclohexylamine. This compound is absorbed into the bloodstream and passes through the kidneys. At high doses in animal studies, cyclohexylamine caused testicular atrophy and impaired sperm production. The European Food Safety Authority's acceptable daily intake is set conservatively to keep cyclohexylamine exposure well below the doses that caused these effects in animals. Human evidence at realistic dietary intakes is limited.
Cyclohexylamine, the gut-bacterial metabolite of cyclamate, caused testicular atrophy and reduced sperm motility in rats at doses of 50 mg/kg body weight per day and above.
EFSA set an ADI of 0-7 mg/kg body weight per day for cyclamate, derived from the cyclohexylamine reproductive no-observed-adverse-effect level in animals with a 100-fold safety factor.
Conversion of cyclamate to cyclohexylamine varies substantially between individuals: non-converters excrete essentially none, while high converters may excrete amounts approaching the level at which animal effects were seen at high cyclamate intakes.
Cancer: IARC Group 3 (not classifiable)
Early 1970s animal studies raised concern that cyclamate might cause bladder cancer, leading the USA to ban it in 1969. Subsequent research did not confirm that cyclamate alone causes bladder cancer. IARC reviewed the evidence in 1980 and again in 1999 and placed cyclamate in Group 3: not classifiable as to carcinogenicity in humans. Some animal studies found that cyclamate at high doses could promote tumour growth when a known carcinogen was given first, but cyclamate alone did not initiate tumours in the same experiments.
IARC classified cyclamates as Group 3 (not classifiable as to their carcinogenicity to humans) based on inadequate evidence in humans and inadequate evidence in animals that cyclamate alone causes cancer.
In two rat studies, sodium cyclamate given after a known bladder carcinogen increased tumour incidence in one study and showed only slight enhancement in a second, suggesting co-carcinogenic rather than primary carcinogenic activity.
Epidemiological studies in diabetic populations (who used saccharin and cyclamate more than the general population) showed no significant increase in bladder cancer risk attributable to these sweeteners.
USA ban still in place; the EU and UK permit it
The US FDA revoked cyclamate's approval in 1969 after early animal bladder-cancer data. A petition to reinstate it has never been granted. The UK and EU permit cyclamate within specific food categories under an ADI, on the grounds that the weight of evidence does not confirm carcinogenicity and that the cyclohexylamine concern is managed by the dose limit. This regulatory split means cyclamate is one of the few food additives that is legal on UK and EU shelves but absent from US products.
The US FDA banned cyclamate from food use in 1969 following animal study data; Abbott Laboratories submitted a reinstatement petition in 1982 which the FDA had not approved as of 2025.
Cyclamate (E952) is authorised for use in Great Britain as of 31 December 2020 under assimilated Regulation (EC) No 1333/2008 Annex II.
Gut microbiome variation and individual exposure
Whether cyclamate poses any meaningful risk depends heavily on whether a person converts it to cyclohexylamine in their gut. This conversion is driven by specific bacteria and is highly variable. People who are high converters are exposed to proportionally more cyclohexylamine from the same intake of cyclamate. The ADI was set to protect even high converters within the studied range, but the uncertainty around conversion rates in the general population is acknowledged by regulators.
The proportion of the population who convert cyclamate to cyclohexylamine varies across studies from approximately 25% to 43%, with conversion rates differing substantially between individuals.
Where it stands with the regulators
Who should be careful
People who want to match US food standards or avoid any sweetener with unresolved regulatory controversy should look for 'cyclamate', 'sodium cyclamate', 'calcium cyclamate', or 'E952' on the label. Those with phenylketonuria should note that cyclamate is sometimes used alongside aspartame (E951) in the same product. No specific clinical population is formally advised to avoid it in UK guidance, but those limiting sweetener intake more broadly will find it mainly in diet drinks, reduced-sugar confectionery, and table-top sweeteners.
The honest read
Cyclamate sits in an unusual position: it is permitted across the UK, EU and many other countries, but has been banned in the USA for over 50 years with no sign of reinstatement. The cancer concern that prompted the US ban was not confirmed in later research, and IARC's 1999 review placed it in the 'not classifiable' group rather than any positive carcinogen category. The active concern that regulators do take seriously is the cyclohexylamine metabolite and its effects on reproductive organs in animals. The ADI is designed to keep exposure below the harmful animal dose, but it rests on a safety factor applied to animal data, and human evidence for the metabolite at realistic dietary exposures is thin. The science here is not settled, and the transatlantic regulatory split reflects genuine disagreement about how to weigh incomplete evidence.
Related additives
Common questions
Is E952 banned in the UK?
No. Cyclamate (E952) is permitted in the UK under assimilated EU Regulation 1333/2008, which was carried into UK law at the end of the Brexit transition period. It is approved for use in diet drinks, table-top sweeteners, reduced-sugar confectionery and other specific food categories. The ban applies in the USA, not the UK or EU.
Why is cyclamate banned in the USA?
The US FDA revoked cyclamate's approval in 1969 after animal studies suggested it might cause bladder cancer when combined with saccharin. Subsequent research did not confirm that cyclamate alone causes cancer in humans, and IARC classified it as Group 3 (not classifiable). A reinstatement petition submitted in 1982 has not been approved. The FDA's position has not changed despite the updated evidence.
What foods contain E952?
In the UK, cyclamate appears mainly in diet or reduced-calorie carbonated drinks, squashes and cordials, table-top sweetener tablets and sachets, sugar-free boiled sweets and chewing gum, and some reduced-sugar jams or preserves. It is often paired with saccharin to balance taste. Look for 'cyclamate', 'sodium cyclamate', 'calcium cyclamate', or 'E952' on the ingredients list.
Is E952 vegan?
Yes. Cyclamate is a synthetic compound with no animal-derived ingredients. It is suitable for vegans and vegetarians. Some products containing it may not be vegan for other reasons, so check the full label.
Sources
- UK FSA Authorised Regulated Food and Feed Products - E952
- IARC Monographs Volume 73 - Cyclamates (NCBI Bookshelf)
- IARC Overall Evaluations of Carcinogenicity - Cyclamates Group 3 (NCBI Bookshelf)
- IARC Monographs Summary and Evaluation, Volume 73, 1999 - Cyclamates
- EFSA AFC Panel Opinion on Cyclamate as a Food Additive (2000)
- UK FSA Approved Additives and E Numbers
- Elcock & Morgan - Update on artificial sweeteners and bladder cancer, European Journal of Cancer Prevention
Aaron Keen is the founder of NutraSafe. He researches and writes every additive entry himself, from the primary sources. About the research →
This is a guide, not medical advice. If an additive affects you, speak to your GP or a dietitian.
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