E-numbers / Preservatives / E252
also: KNO3 · saltpetre · saltpeter
Saltpetre, used in slow-cured ham and salami. It turns into nitrite as the meat cures. Processed meat causes bowel cancer, and nitrite is one of the reasons.
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Pork*, Salt, Antioxidant (Sodium Ascorbate), Preservatives (Sodium Nitrite, Potassium Nitrate), *Made with 149g of Pork per 100g of finished product
Regularly eating processed and cured meat is linked to bowel cancer.
UK supermarket foods that declare E252: 616 of the 43,325 we checked (1.4%)
Counted by its code or its name in the ingredient list.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
Why it’s worth knowing. Regularly eating processed and cured meat is linked to bowel cancer. The nitrite formed from potassium nitrate reacts with meat protein to make nitrosamines, compounds classed as probable or known causes of cancer. IARC classes processed meat as causing cancer (Group 1).
Potassium nitrate, known as saltpetre, is a mineral salt. It is the potassium version of sodium nitrate (E251) and one of the nitrate curing salts. It does not preserve meat by itself. Bacteria in the meat slowly turn it into nitrite, which does the work.
During slow curing, bacteria turn potassium nitrate into nitrite. The nitrite gives cured meat its pink colour, stops the growth of the bacterium that causes botulism, and slows fat going rancid. Because the change takes time, it suits long-cured products like dry-cured ham. Quick-cured products use sodium nitrite (E250), which works straight away.
Mainly traditional and slow-cured meat: dry-cured ham, some salamis and hard sausages. It is also allowed in some hard and semi-hard cheeses, and may appear in some cured fish. UK labels call it potassium nitrate or E252.
In 2026 the NutriNet-Santé study reported that French adults who ate more potassium nitrate had 13% more cancer overall and 22% more breast cancer. These are observational studies.
Among 105,260 French adults followed for an average of 7.5 years, higher intake of potassium nitrate was linked to a 13% higher risk of cancer overall and a 22% higher risk of breast cancer.
IARC, the WHO's cancer agency, classed processed meat as causing bowel cancer in humans (Group 1) in 2015, based on studies in people. One reason it gives is the N-nitroso compounds formed when nitrite reacts with protein in the gut. Every 50g of processed meat a day was linked to an 18% higher risk. For the full picture on cured meat, see our page on sodium nitrite (E250).
IARC classed processed meat as causing cancer in humans (Group 1), with sufficient evidence from human studies for bowel cancer. N-nitroso compounds from nitrite are one of the explanations of how.
Pooling the studies, each extra 50g of processed meat a day was linked to a 16% higher risk of bowel cancer.
Potassium nitrate turns into nitrite during curing. Nitrite reacts with parts of meat protein in acidic conditions, such as in the stomach, to form N-nitroso compounds, including nitrosamines. Several of the nitrosamines formed this way are classed by IARC as probably causing cancer (Group 2A). More form when meat is cooked at high heat.
N-nitrosodimethylamine (NDMA) and several related nitrosamines formed in nitrite-treated meat are classed as probably causing cancer in humans (Group 2A).
A review of animal and human evidence found a consistent link between nitrite from processed meat and bowel cancer, with N-nitroso compounds a plausible route.
European reviewers looked at sodium and potassium nitrate again in 2017, kept them approved and kept the daily limit for nitrate at 3.7mg per kg of body weight. They noted that nitrate from additives plus the nitrate in vegetables and water can go over that limit in people who eat the most, particularly children.
Reviewers kept a daily limit for nitrate of 3.7mg per kg of body weight and kept added nitrates allowed at current levels, but noted that nitrate from all food sources together can pass the limit in high-intake groups.
Daily limit. 3.7mg of nitrate per kg of body weight a day (European reviewers, 2017).
Anyone cutting processed meat for bowel cancer risk should look for potassium nitrate, potassium nitrite, sodium nitrate, sodium nitrite, E252, E251, E250 or E249 on cured meat. Children, people with low body weight and anyone who already gets a lot of nitrate from vegetables and water should watch how often they eat cured meat with these additives.
The link between processed meat and bowel cancer is one of the most consistent findings in nutrition research, and the IARC Group 1 classification rests on decades of human studies, not just animal work. A large 2026 French study linked potassium nitrate itself to 13% more cancer and 22% more breast cancer.
No. Potassium nitrate is approved in the UK and EU in some cured meat, cheese and fish, within set foods and limits.
E252 itself is not classified as a cause of cancer, but during curing it turns into nitrite, which can form nitrosamines in the meat and in the gut. IARC classes processed meat as causing bowel cancer in humans (Group 1), and nitrite-derived compounds are one of the likely reasons.
Mainly dry-cured and traditionally slow-cured meat, such as dry-cured ham, hard sausages and salamis. It may also appear in some cured cheeses and cured fish. Look for potassium nitrate or E252.
The chemical is not from animals, but it is used almost only in meat and fish, so the foods it is in are not vegan.
Last reviewed: 9 November 2026
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