Sodium nitrite is very soluble in water and can be easily taken as a drink. In the acid environment of the stomach, some of the nitrite is converted to nitrate-releasing nitric oxide (NO).
3NaNO2 + 2HCl → 2NaCl + NaNO3 - + 2NO + H2 O
When the remainder of the nitrite reaches the small intestine the nitrite ‘cation’ (NO2
) is absorbed into the bloodstream and
causes methemoglobin (it alters the hemoglobin in red blood cells). Methemoglobin is an altered form of haemoglobin with a much higher affinity for oxygen. This greatly restricts the oxygen needed for cellular function in the brain and other essential organs.
The protective enzyme system (methemoglobin reductase, more properly called ‘cytochrome b5 reductase’) is normally present in red blood cells. However, with high nitrite absorption rates, this protection is overwhelmed and death from cerebral (hypemic) hypoxia results.
Sodium nitrite is commonly used as a meat preservative
