E-numbers / Sweeteners / E962
also: Twinsweet · Aspartame-acesulfame
A sweetener made by combining aspartame and acesulfame K into one compound, used to sweeten low-sugar and diet products.
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Contains aspartame, which IARC classified as a possible carcinogen in 2023, based on limited evidence linking it to liver cancer.
Why it’s worth knowing. Contains aspartame, which IARC classified as a possible carcinogen in 2023, based on limited evidence linking it to liver cancer. People born with phenylketonuria cannot metabolise phenylalanine, a breakdown product of aspartame, and must avoid it.
Aspartame-acesulfame salt is the equimolar salt formed when aspartame (E951) and acesulfame K (E950) are combined. The result is a single crystalline compound sold commercially as Twinsweet. Once ingested it dissociates into its two component sweeteners, so the body handles it identically to consuming aspartame and acesulfame K separately. It is roughly 350 times sweeter than sugar by weight.
It provides intense sweetness with very few calories. Acesulfame K contributes an immediate sweetness onset; aspartame provides a cleaner, more sugar-like flavour with a longer finish. The combination in salt form reduces bitterness that can occur when either is used alone, allowing manufacturers to use lower total quantities while achieving a more balanced sweet taste.
Found mainly in diet soft drinks, sugar-free chewing gum, low-calorie table-top sweeteners, diet fruit squashes, sugar-free confectionery, and reduced-sugar dairy desserts. On a UK ingredient label it will appear as 'sweetener (aspartame-acesulfame salt)' or 'sweetener (E962)'. UK food law also requires the label to carry 'contains a source of phenylalanine' whenever E962 is present.
In July 2023, the International Agency for Research on Cancer classified aspartame as Group 2B, meaning 'possibly carcinogenic to humans'. The classification was based on limited human evidence, mainly observational studies suggesting an association with hepatocellular carcinoma (liver cancer). IARC noted the evidence was not strong enough to establish causation, and the parallel JECFA review left the acceptable daily intake for aspartame unchanged. Because E962 dissociates to release aspartame in the body, this classification applies to it directly. EFSA has not published a new standalone opinion on aspartame following the 2023 IARC classification; its 2013 re-evaluation remains the current EFSA position, though an ongoing systematic re-evaluation programme covering aspartame and E962 is under way and had not concluded as of mid-2026.
IARC classified aspartame as Group 2B (possibly carcinogenic to humans) based on limited evidence from human observational studies for hepatocellular carcinoma and limited mechanistic evidence.
JECFA reviewed the same dataset and maintained the aspartame ADI at 0 to 40 mg/kg body weight per day, concluding the existing evidence did not justify changing the established limit.
EFSA's 2013 full re-evaluation of aspartame remains its current authoritative opinion. No updated EFSA opinion has been published following the IARC Group 2B classification. EFSA's systematic sweeteners re-evaluation programme includes aspartame and E962 but had not concluded as of mid-2026.
Aspartame is broken down in the gut to phenylalanine, aspartic acid, and methanol. People with phenylketonuria (PKU) carry a genetic mutation that prevents them from metabolising phenylalanine normally; it accumulates to levels that cause brain damage and intellectual disability. This is not a toxicological concern for the general population but is a serious hazard for the roughly 1 in 10,000 people born with PKU. UK law requires a warning on every product containing aspartame or aspartame-acesulfame salt.
Aspartame provides approximately 55% phenylalanine by weight after hydrolysis. In people with phenylketonuria, phenylalanine cannot be cleared via the normal phenylalanine hydroxylase pathway, leading to neurotoxic accumulation.
UK food law mandates the statement 'contains a source of phenylalanine' on any food containing aspartame or aspartame-acesulfame salt, applied under assimilated Regulation (EU) 1333/2008.
EFSA published a full re-evaluation of acesulfame K (E950) in April 2025. The panel established a revised ADI of 15mg/kg body weight per day, based on a 2-year chronic toxicity and carcinogenicity study in rats. The panel found it unlikely that acesulfame K intake is associated with cancer, disturbances of glucose or insulin homeostasis, cardiovascular risk, or organ toxicity. A genotoxicity concern was identified for one impurity, 5-chloro-acesulfame, and the panel recommended either a maximum impurity limit of 0.1mg/kg or submission of appropriate genotoxicity data. Because E962 dissociates to acesulfame K on ingestion, this re-evaluation applies directly to it.
EFSA's 2025 re-evaluation of acesulfame K established an ADI of 15mg/kg body weight per day, revised upward from the 9mg/kg set in a prior assessment. The panel found no safety concern for genotoxicity of acesulfame K itself but identified a concern for the impurity 5-chloro-acesulfame.
In a mouse model, acesulfame K consumption altered gut microbiome diversity and was linked to increased incidence of infection-related illness, though the dose used was higher than typical human dietary exposure.
Several observational and lab studies have raised questions about whether regular intake of non-nutritive sweeteners including aspartame and acesulfame K disrupts gut bacteria in ways that could affect blood sugar regulation. The evidence is mixed and largely observational. Causation in humans has not been established.
A randomised controlled trial in healthy adults found that consuming saccharin or stevia altered gut microbiome composition and glucose response in some participants, raising broader questions about sweetener effects on the gut, though aspartame did not show the same effect in that trial.
Large observational cohort data from the NutriNet-Sante study associated total sweetener consumption, including aspartame and acesulfame K, with modestly higher risk of cardiovascular events; confounding by dietary pattern could not be excluded.
People with phenylketonuria (PKU) must avoid E962 entirely, as it releases phenylalanine in the gut. Look for 'contains a source of phenylalanine' on pack, or check the ingredients list for 'aspartame-acesulfame salt' or 'E962'. Pregnant women with PKU are under stricter controls and should follow their metabolic dietitian's guidance. People managing their overall sweetener intake should be aware this compound contributes to both aspartame and acesulfame K totals.
E962 sits at the centre of a contested science debate. The 2023 IARC Group 2B classification for aspartame generated significant headlines, but IARC's own framework explicitly states Group 2B means the evidence is limited, not that cancer causation is established. The same week, JECFA looked at the identical dataset and held the ADI firm. EFSA has not issued a new opinion on aspartame since 2013, and its ongoing sweeteners re-evaluation programme had not concluded as of mid-2026. The acesulfame K component received a new EFSA opinion in 2025, which revised the ADI upward to 15mg/kg per day and found no cancer signal, but flagged a genotoxicity concern for one impurity. The gut microbiome research is genuinely uncertain: lab and animal signals exist, large observational studies have found associations with cardiovascular risk, but the human trial evidence is mixed and confounding is hard to rule out. The science here is live, not settled.
No. E962 is on the UK FSA's approved additives list and is permitted under the assimilated EU Regulation 1333/2008 retained in UK law. It remains approved as of 2024.
Yes. Once consumed, E962 breaks apart into aspartame and acesulfame K. Any product containing E962 contributes to your total aspartame consumption in the same way as a product listing aspartame directly. IARC classified aspartame as a possible carcinogen in 2023; the current acceptable daily intake is 40mg/kg body weight per day.
E962 is used mainly in diet and sugar-free products: carbonated soft drinks, sugar-free chewing gum, table-top sweeteners, reduced-calorie dairy desserts, and some reduced-sugar confectionery. On pack it appears as 'sweetener (aspartame-acesulfame salt)' or 'sweetener (E962)'.
Yes. Aspartame-acesulfame salt is produced synthetically and contains no animal-derived ingredients. It is suitable for vegans and vegetarians.
Last reviewed: 20 June 2026
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