What is it?
Sodium nitrate is the sodium salt of nitric acid, a white crystalline solid found naturally in soil and some vegetables. In food it is a curing salt: a store of nitrate that bacteria slowly turn into nitrite as meat cures.
E-numbers / Preservatives / E251
Sodium nitrate
also: NaNO3 · Chile saltpetre
A curing salt used in long-cured ham, salami and chorizo. It turns into nitrite. Processed meat causes bowel cancer, and nitrite is one of the reasons.
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Pork (88%), Water, Salt, Preservatives: Sodium Nitrite, Sodium Nitrate, Potassium Nitrate, Acidity Regulator: Sodium Carbonate, Antioxidant: Sodium Ascorbate
E251
Sodium nitrate
Nitrate turns into nitrite in the body, which can form N-nitroso compounds linked to bowel cancer.
VeganVegetarian
UK supermarket foods that declare E251: 285 of the 43,325 we checked (0.7%)
Counted by its code or its name in the ingredient list.
Only 1.8% of these labels print “E251”. Most use the name: look for “sodium nitrate”.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
How common it is in UK food, by aisle
- Fresh meat, poultry and fish123 products2.5% of 4,835
- Cooked and cured meats91 products4.7% of 1,938
- Ready meals and pizza30 products0.6% of 4,833
- Bread and bakery17 products0.5% of 3,682
What sodium nitrate is, what it does and where you will see it
Why it’s worth knowing. Nitrate turns into nitrite in the body, which can form N-nitroso compounds linked to bowel cancer. The WHO's cancer agency classes regular processed meat eating as a cause of bowel cancer.
What does it do?
During curing, bacteria gradually turn sodium nitrate into sodium nitrite (E250). The nitrite reacts with the red pigment in meat to give bacon, ham and salami their lasting pink colour. It also stops the growth of the bacterium that causes botulism and slows fat going rancid. Because it releases nitrite slowly, it suits meat that cures for a long time.
Where you will see it
Cured hams, dry-cured and fermented meats such as salami and chorizo, long-aged bacon and some cured fish. It is also allowed on the rind of some cheeses. UK labels call it sodium nitrate, E251 or curing salt, sometimes alongside E250 (sodium nitrite).
What the science says
Processed meat causes bowel cancer
In 2015 IARC, the WHO's cancer agency, classed processed meat as causing bowel cancer in humans (Group 1). The classification is for the food, not a single additive, but added nitrate and nitrite are part of how it may happen, because they can form N-nitroso compounds in the gut. Every 50g of processed meat a day was linked to about 18% higher risk. For more on cured meat, see our page on sodium nitrite (E250).
IARC classed processed meat as causing cancer in humans (Group 1), mainly bowel cancer. Every 50g of processed meat eaten a day was linked to about an 18% higher risk.
2015Review of many studiesIARC Monographs Volume 114, Lancet Oncology, Bouvard et al.
IARC classed ingested nitrate as probably causing cancer in humans (Group 2A) when it leads to N-nitroso compounds forming in the body.
2010ObservationalIARC Monographs Volume 94, Ingested Nitrate and Nitrite, and Cyanobacterial Peptide Toxins
How nitrate may lead to cancer
When nitrite from nitrate meets parts of protein in the acidic stomach and in the bowel, it can form N-nitroso compounds, many of which cause cancer in animals. Haem iron, the iron in red meat, speeds this up.
Haem iron in red and processed meat speeds up the formation of N-nitroso compounds in the gut, a plausible link between processed meat and bowel cancer.
2015Lab and animal studyIARC Monographs Volume 114
How much processed meat the NHS advises
The NHS advises that people who eat more than 90g of red and processed meat a day cut down to 70g. The advice covers all processed meat, not only meat with nitrate, but nitrate-cured meat is the main category it applies to.
The NHS advises eating no more than 70g of red and processed meat a day, and cutting down if you eat more, because of the link with bowel cancer found in population studies.
Clinical guidanceNHS, Red meat and bowel cancer guidance
Babies and blue baby syndrome
A lot of nitrate can turn haemoglobin into a form that cannot carry oxygen well. Babies under six months are most at risk.
High doses of nitrate cause methaemoglobinaemia in babies, reducing how well blood carries oxygen. Maximum levels in food are set partly to protect them.
2017Regulator reviewEFSA Panel on Food Additives and Nutrient Sources (ANS), re-evaluation of nitrites and nitrates as food additives
The 2017 European review
European reviewers looked at nitrates and nitrites as additives in 2017 and kept a daily limit for nitrate of 3.7mg per kg of body weight. They found that nitrate from all sources, including vegetables and water, could go over it in people who eat the most, children included.
Reviewers kept a daily limit of 3.7mg of nitrate per kg of body weight. Total nitrate from all food sources could go over it in high-intake groups.
2017Regulator reviewEFSA Journal, ANS Panel re-evaluation of sodium and potassium nitrites and nitrates
Where it stands with the regulators
Approved in the UK and the EU
Daily limit. 3.7mg of nitrate per kg of body weight a day, covering E251 and E252 (European reviewers, 2017).
- Legal basis
- On the Food Standards Agency's approved list for Great Britain
- Permitted foods
- Processed meat that is not heat-treated · Heat-treated processed meat · Traditional cured meats · Some cured fish · Hard, semi-hard and processed cheese (against mould on the rind)
- Maximum levels
- Depends on the food. In processed meat usually 150 to 300mg per kg of added nitrate.
- History
- European reviewers completed a full review in 2017, kept them approved, and noted total nitrate intake could exceed the limit in high-intake groups including children. IARC's 2015 processed meat classification brought more scrutiny, and the FSA has commissioned work on nitrates and nitrites in cured meat since. No UK ban is in force.
Who should be careful
People who eat processed meat often, particularly every day, have the highest total exposure. Babies under six months should not have foods with added nitrate. People with conditions affecting how blood carries oxygen should talk to their doctor about cured meat. Look for sodium nitrate, E251 or curing salt.
The honest read
At the diet level, IARC's classification of processed meat as causing cancer is one of the more solid findings in nutrition research, backed by large pooled studies from many countries. The explanation, nitrite, haem iron and protein forming N-nitroso compounds in the gut, is biologically plausible and seen in lab and animal work. Whether lower limits or other preservatives would cut population risk is still being researched.
Common questions about sodium nitrate
Is E251 banned in the UK?
No. Sodium nitrate is approved in the UK in specific foods, including cured and processed meat, up to set limits.
Does sodium nitrate cause cancer?
IARC classes ingested nitrate as probably causing cancer in humans (Group 2A) when it leads to N-nitroso compounds forming in the body. Processed meat, the food it is mostly used in, is classed as causing bowel cancer (Group 1).
What foods contain E251?
Mainly cured and fermented meat: dry-cured ham, salami, chorizo, pepperoni, long-cured bacon and some cured fish. It may also be on the rind of some hard cheeses. Look for sodium nitrate or E251.
Is E251 vegan?
The salt is a mineral, not from animals. But it is used almost only in cured meat and fish, so the foods it is in are not vegan.
Sources
- IARC Monographs Volume 114: Red Meat and Processed Meat (2018 update of 2015 findings)
- Bouvard et al., Carcinogenicity of consumption of red and processed meat, Lancet Oncology
- IARC Monographs Volume 94: Ingested Nitrate and Nitrite, and Cyanobacterial Peptide Toxins
- EFSA ANS Panel, Re-evaluation of sodium and potassium nitrites and nitrates as food additives, EFSA Journal
- UK Food Standards Agency: Nitrates and Nitrites - The Science Explained
- UK Food Standards Agency: Approved Additives and E Numbers
- NHS: Red meat and bowel cancer
Last reviewed: 9 November 2026
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