E250 — Sodium nitrite
Also labelled: Natriumnitrit · nitrite curing salt · E249–E252 group
Sodium nitrite does a job nothing else does as well — it stops botulism in cured meat — but it also forms nitrosamines when meat is cured and then cooked hot. Frela rates it high because it is the additive most directly tied to a Group 1 carcinogen classification for the foods it appears in.
At a glance
- E number
- E250
- Class
- Preservative
- Origin
- Synthetic inorganic salt, usually sold to butchers pre-diluted in table salt
- EU status
- Authorised, with maximum levels tightened in 2023
- Acceptable daily intake
- 0.07 mg per kg of body weight per day, as nitrite ion (EFSA, 2017)
- Typically found in
- Bacon, ham, salami, hot dogs, cured and smoked sausage, some cheeses
What it actually is
Sodium nitrite is a simple inorganic salt. Butchers almost never handle it neat: in Germany it arrives as Nitritpökelsalz, ordinary table salt with roughly 0.4–0.5% sodium nitrite mixed in, precisely because the pure compound is toxic in small quantities and easy to overdose by hand.
It is not a flavour enhancer and not a colour in the usual sense, though it produces both effects. Its primary function is antimicrobial, and it is unusually good at one specific thing.
Why it is still used
Nitrite is the most effective known inhibitor of Clostridium botulinum, the bacterium that produces botulinum toxin. Cured meat is close to an ideal environment for it: low oxygen, moist, protein-rich, often stored for weeks. Before nitrite curing was standardised, botulism outbreaks traced to preserved sausage were a recurring cause of death — the word botulism comes from botulus, Latin for sausage.
It also reacts with myoglobin to form nitrosomyoglobin, which is why ham stays pink instead of turning the grey-brown of cooked pork, and it contributes the characteristic cured flavour. Those are the visible effects, but the safety function is the reason regulators keep authorising it.
What the evidence says
The concern is not nitrite itself but what it becomes. Under heat, and in the acidic environment of the stomach, nitrite can react with amines from protein to form N-nitroso compounds. Several nitrosamines in that family are established animal carcinogens, and frying or grilling cured meat at high temperature increases their formation.
In 2015 the International Agency for Research on Cancer classified processed meat as Group 1, carcinogenic to humans, based on sufficient evidence for colorectal cancer. That classification is about processed meat as a food category, not about sodium nitrite in isolation — but nitrite curing is one of the main mechanisms proposed to explain it. IARC separately classified ingested nitrite under conditions that result in endogenous nitrosation as Group 2A, probably carcinogenic.
EFSA re-evaluated nitrites in 2017 and set an acceptable daily intake of 0.07 mg per kg of body weight. It concluded that exposure from nitrite used as an additive stays within that ADI for most people, but that total exposure from all dietary sources can exceed it for some children. In 2023 the EU lowered the maximum permitted levels in most cured meat categories.
The 'nitrite-free' label is not what it looks like
Bacon and ham marketed as uncured, nitrite-free or naturally cured are usually cured with celery powder, celery juice concentrate or sea salt cultured with a starter organism. These are concentrated natural nitrate sources, and the nitrate converts to nitrite during curing — which is the entire point, because otherwise the meat would not cure.
The chemistry in the finished product is broadly the same, and measured nitrite levels in celery-cured products are often comparable to conventionally cured ones. Frela treats these products on their ingredients and their processing, not on the marketing claim.
How Frela scores it
Frela rates E250 high risk, which sets the additive component of the score to its floor. Frela scores by the riskiest additive present rather than averaging, so one high-risk additive is not diluted by a list of harmless ones.
Cured meats also tend to score poorly on the other components — high salt and saturated fat pull the Nutri-Score part down, and NOVA classifies them as ultra-processed. A product is not being punished four times for the same thing; those are genuinely separate measurements that happen to point the same way for this category.
Common questions
Is bacon with nitrite dangerous to eat occasionally?
The IARC classification describes a hazard identified across populations and long-term intake, not the risk from a single meal. Public health guidance in most European countries is to limit processed meat rather than eliminate it. Frela's rating reflects the strength of the classification, not a claim about any one breakfast.
Why is a preservative that prevents botulism rated high?
Because Frela's additive rating measures the weight of evidence linking a substance to health concerns, not whether it earns its place technologically. Nitrite is genuinely useful and genuinely implicated. Both are true.
Does cooking method matter?
It appears to. Nitrosamine formation increases with high-temperature cooking, so frying bacon until crisp generates more than gentle heating. This is one reason guidance often mentions cooking method alongside quantity.
Sources
- EFSA — Re-evaluation of potassium nitrite (E249) and sodium nitrite (E250) as food additives (2017)
- IARC Monographs Volume 114 — Red meat and processed meat
- Commission Regulation (EU) 2023/2108 — amending permitted levels of nitrites and nitrates
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