Saccharin

also: Sodium saccharin · Sweet'N Low · Hermesetas · Benzosulfimide

The oldest artificial sweetener, 300 to 500 times sweeter than sugar. A 2022 trial found it changed gut bacteria and blood sugar in some people.

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An ingredient list from the soft drinks and juices aisle

Carbonated Water, Sugar, Acid (Citric Acid), Preservative (Sodium Benzoate), Sweeteners (Sodium Saccharin, Aspartame), Colour (Anthocyanins), Flavourings

E954Sweetener · Synthetic

Saccharin

High doses caused bladder tumours in rats.

VeganVegetarianHalalKosher

UK supermarket foods that declare E954: 174 of the 43,325 we checked (0.4%)

Counted by its code or its name in the ingredient list.

Only 2.3% of these labels print “E954”. Most use the name: look for “saccharin”.

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 juices83 products3.2% of 2,627
Sauces, dressings and condiments22 products0.8% of 2,776
Crisps and savoury snacks20 products0.6% of 3,428
Fruit, vegetables and salad11 products0.4% of 2,631

What saccharin is, what it does and where you will see it

Why it’s worth knowing. High doses caused bladder tumours in rats. Newer research links regular intake to changes in gut bacteria.

What is it?

Saccharin is a man-made sweetener, made from toluene or phthalic anhydride, chemicals from the petrochemical industry. It has no calories. It comes as saccharin or as its sodium, potassium or calcium salt.

What does it do?

It fits the sweet taste receptors on the tongue far more strongly than sugar does, so very little tastes very sweet with no energy.

Where you will see it

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.

What the science says

Bladder tumours in rats, and why the classification changed

In studies from the 1970s and 1980s, high doses of saccharin caused bladder tumours in male rats. IARC moved saccharin in 1999 from possibly causing cancer (Group 2B) to not classifiable (Group 3).

Saccharin causes bladder tumours in male rats at high doses.

1999Animal studyIARC Monograph, Volume 73

IARC moved saccharin to Group 3 (not classifiable as to whether it causes cancer in humans).

1999Regulator reviewIARC Overall Evaluations of Carcinogenicity, Supplement 7 and Volume 73

Two large case-control studies found small raised risks in some subgroups, but the results did not agree between studies.

ObservationalUS National Cancer Institute, Artificial Sweeteners and Cancer fact sheet

It can change gut bacteria and blood sugar

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.

2022Randomised trial in peopleSuez et al., Cell

In mice, saccharin changed gut bacteria and worsened blood sugar control, and antibiotics reversed this, pointing to the bacteria as the route.

2014Lab and animal studySuez et al., Nature

A higher daily limit in 2024

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.

Reviewers set a daily limit of 9mg per kg of body weight for saccharin and its salts after a systematic review of the evidence.

2024Regulator reviewEFSA Journal, Re-evaluation of saccharin and its sodium, potassium and calcium salts (E 954)

The old US cancer warning

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.

2000Regulator reviewUS National Toxicology Program

Where it stands with the regulators

Permitted as a sweetener in the UK and the EU

Daily limit. 9mg per kg of body weight a day (European reviewers, 2024).

Legal basis: On the Food Standards Agency's approved list for Great Britain
Permitted foods: Sweetener tablets and sachets · Reduced-energy or no-added-sugar soft drinks · Reduced-energy or no-added-sugar jams and marmalades · Reduced-energy or no-added-sugar sweets and chewing gum · Some sauces and mustards · Medicines and supplements
Maximum levels: Set for each type of food.
History: In 1977, after the rat bladder studies, the US FDA proposed a ban and the US brought in warning labels. IARC classed it as possibly causing cancer (Group 2B), then moved it to not classifiable (Group 3) in 1999. The US took it off its carcinogen list in 2000. In the EU and UK it has stayed allowed throughout, within set limits. European reviewers finished a full review in 2024 and set a daily limit of 9mg per kg.

Who should be careful

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.

The honest read

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 and it did not happen to everyone.

Common questions about saccharin

Is E954 banned in the UK?

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.

Does saccharin cause cancer?

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. The US took it off its list of suspected carcinogens in 2000.

What foods contain E954?

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.