E-numbers / Sweeteners / E954
also: Sodium saccharin · Sweet'N Low · Hermesetas · Benzosulfimide
The oldest artificial sweetener, 300 to 500 times sweeter than sugar. Its cancer scare was about rats. A 2022 trial found it changed gut bacteria and blood sugar in some people.
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Carbonated Water, Sugar, Acid (Citric Acid), Preservative (Sodium Benzoate), Sweeteners (Sodium Saccharin, Aspartame), Colour (Anthocyanins), Flavourings
High doses caused bladder tumours in rats, by a route not thought to apply to people.
174
of the 43,325 UK supermarket foods we checked declare E954 in their ingredients
That is 0.4%, counted by its code or its name.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
Why it’s worth knowing. High doses caused bladder tumours in rats, by a route not thought to apply to people. Newer research links regular intake to changes in gut bacteria.
Saccharin is a man-made sweetener, made from toluene or phthalic anhydride, chemicals from the petrochemical industry. It has no calories and the body does not break it down. It comes as saccharin or as its sodium, potassium or calcium salt.
It fits the sweet taste receptors on the tongue far more strongly than sugar does, so a tiny amount tastes very sweet with no energy. The body does not digest or absorb it in any useful way, and it passes out largely unchanged.
Sweetener tablets and sachets, diet fizzy drinks, sugar-free squash and cordials, low-calorie jams, sugar-free chewing gum, some medicine syrups and toothpaste. It is often mixed with other sweeteners. UK labels call it saccharin, sodium saccharin, calcium saccharin or E954.
In studies from the 1970s and 1980s, high doses of saccharin caused bladder tumours in male rats. Later work showed this happens through crystals forming in rat urine, which does not happen in human urine. On that basis IARC moved saccharin in 1999 from possibly causing cancer (Group 2B) to not classifiable (Group 3). Large studies in people have not found a clear link with bladder cancer.
Saccharin causes bladder tumours in male rats at high doses, but through urine chemistry specific to rats that is not thought to apply to humans.
IARC moved saccharin to Group 3 (not classifiable as to whether it causes cancer in humans), noting the rat bladder tumour route does not carry over to human biology.
Two large case-control studies found small raised risks in some subgroups, but the results did not agree between studies and no clear link was established.
A 2022 randomised trial gave people saccharin for two weeks. Their gut bacteria changed, and some of them had higher blood sugar after a standard glucose drink. When the researchers moved those people's gut bacteria into germ-free mice, the mice showed the same blood sugar changes. The effect was not seen in everyone and depended on the bacteria each person started with. Earlier mouse studies had pointed the same way.
Saccharin changed the make-up of gut bacteria and, in some participants, raised blood sugar responses in a short randomised trial.
In mice, saccharin changed gut bacteria and worsened blood sugar control, and antibiotics reversed this, pointing to the bacteria as the route.
European reviewers completed a full review of saccharin in 2024 and set a daily limit of 9mg per kg of body weight, higher than the old limit. They estimated that intake in Europe is below it for most groups, though people who have a lot of different sweetened products could get close.
Reviewers set a daily limit of 9mg per kg of body weight for saccharin and its salts after a systematic review of the evidence.
From 1977 saccharin carried a compulsory cancer warning in the United States, because of the rat findings. In 2000, after the IARC change and a review by the US National Toxicology Program, it was taken off the US list of suspected carcinogens and the warning was dropped.
Saccharin was taken off the US National Toxicology Program's Report on Carcinogens after the rat tumour route was found not to apply to humans.
Daily limit. 9mg per kg of body weight a day (European reviewers, 2024).
Unlike aspartame, saccharin is not a problem for people with phenylketonuria. People who have a lot of sweetened products every day may want to keep track, since several sweeteners are often combined. Look for E954, saccharin, sodium saccharin or calcium saccharin.
Saccharin went through one of the biggest reversals in additive history. It was feared as a cancer risk in the 1970s and 1980s, and the warnings were dropped once the rat tumour route was shown not to work the same way in people. Studies in people have not established a bladder cancer link. The open question now is gut bacteria: a 2022 randomised trial found saccharin changed blood sugar responses in some people through their gut bacteria. That finding is real but early, it did not happen to everyone, and the long-term effects are unknown.
No. Saccharin is approved in the UK and EU and is on the Food Standards Agency's list. It can be used in set foods up to set limits.
High doses caused bladder tumours in male rats in 1970s studies, and IARC classed it as possibly causing cancer (Group 2B). In 1999 IARC moved it to Group 3, not classifiable, after the rat route was found not to apply to people. Large human studies have not found a clear bladder cancer link, and the US took it off its list of suspected carcinogens in 2000.
Mainly sweetener tablets, diet fizzy drinks, sugar-free squash, low-calorie jams, sugar-free chewing gum and some medicine syrups. It is often combined with other sweeteners. Look for E954, saccharin, sodium saccharin or calcium saccharin.
Yes. It is made in a factory from chemicals, with nothing from animals.
Last reviewed: 20 June 2026
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