What it is

Sodium nitrite keeps cured meat pink and inhibits growth of the bacterium that causes botulism 12.

E 250 (INS 250) is NaNO2 13. Sodium erythorbate, when added, speeds nitrite reduction to nitric oxide 4.

How often it is used

Sodium nitrite was listed on 7,144 of 126,556 French packaged foods in 2019, seventh among additives 4.

Of 106,489 French adults, 73.93% consumed it, population mean 0.28 mg/day; 0.45%, or 0.61% of consumers, exceeded the acceptable daily intake 5.

In the body

Swallowed nitrite is absorbed almost completely, then excreted mostly as urinary nitrate 1.

Oral bacteria reduce 5 to 36% of salivary nitrate to nitrite 1. Nitrite oxidises haemoglobin to methaemoglobin, which impairs oxygen delivery 1. In the stomach, nitrite-derived dinitrogen trioxide nitrosates secondary amines 1. CYP2E1 α-hydroxylates N-nitrosodimethylamine (NDMA); the product decomposes to DNA-methylating methyldiazonium ions 6.

Nitrosation of dimethylamine by nitrite and activation of NDMAGastric lumen, then hepatocyte endoplasmic reticulum and nucleus
  1. Nitrite (NO2−)
  2. Protonation by gastric acid, non-enzymaticpKa 3.3 to 3.4; about half of gastric nitrite is protonated
  3. Nitrous acid (HNO2)
  4. Acid-catalysed condensation of two HNO2, non-enzymaticNitrosation rate rises with the square of nitrite; N2O3 also yields NO and NO2
  5. Dinitrogen trioxide (N2O3)
  6. N-Nitrosation, non-enzymaticDimethylamine, unprotonatedAscorbateErythorbateSecondary amines give stable nitrosamines; primary amines decompose to N2
  7. N-Nitrosodimethylamine (NDMA)
  8. Cytochrome P450 2E1 (CYP2E1), α-hydroxylationO2, NADPH via cytochrome P450 reductaseMainly hepatic; competing CYP2E1 denitrosation yields methylamine
  9. α-Hydroxydimethylnitrosamine
  10. Spontaneous decompositionAlso yields formaldehyde
  11. Methyldiazonium ion
  12. Non-enzymatic methylation of guanineUnrepaired, it causes G to A transitions; MGMT removes the methyl group
  13. O6-Methylguanine in DNA

What studies show

French adults eating more sodium nitrite developed prostate cancer and type 2 diabetes more often 78.

Over a median 6.8 years, prostate cancer developed in 163 of 8157 high-intake men and 56 of 5456 non-consumers (hazard ratio 1.62, 95% CI 1.17 to 2.25); colorectal cancer in both sexes, 1.22 (0.85 to 1.75) 7. Over a median 7.3 years, type 2 diabetes cases were 450 in 268,950 person-years with higher exposure, 154 in 153,593 without (hazard ratio 1.54, 1.26 to 1.90) 8.

EFSA set the acceptable daily intake, 0.07 mg nitrite ion/kg body weight, by benchmark dose for doubled methaemoglobin in rats 1. At that intake, NDMA formed in the body had a margin of exposure above 10,000; NDMA and NDEA preformed in meat, below 10,000 at high intake 1.

Regulation

Each jurisdiction limits it mainly to cured meat 212133.

JurisdictionLimit
EUSince 9 October 2025, 80 mg/kg nitrite ion added to most meat products, 55 if sterilised 2
US200 ppm in cured meat; pumped bacon 120 ppm with ascorbate or erythorbate 12
JapanOnly meat products, whale bacon, fish sausage and ham, and roe; nitrite ion residues ≤0.070 g/kg 13
China0.15 g/kg in meat products; residues 30 to 70 mg/kg as sodium nitrite 3