Sodium nitrite is a chemical compound which is used principally as an additive in meats and other foods. It has properties that preserve color and freshness, especially in processed meats. In its pure state, it is a white or yellowish powder, with a texture somewhat like salt. It is considered a salt in the chemical sense, meaning that it is composed of positively charged ions of a metal -- sodium -- and negatively charged non-metal ions -- nitrite.
There are at least three purposes accomplished by the addition of sodium nitrite to certain food products. The first is the preservation of color. Sodium nitrite preserves the red color of meats and some types of fish so that they remain red even if they are cooked while being processed.
Another purpose is to inhibit the growth of the bacteria Clostridium botulinum. This species of microorganism is highly dangerous when it is present in food products, because it produces a neurotoxin which causes a set of symptoms in humans known as botulism. These symptoms include muscular paralysis, which can lead to respiratory failure and death.
Sodium nitrite, because of how it is used in the process of curing meats, also maintains freshness overall by slowing the development of rancid flavors or odors in the food it is used to treat. It also has other applications outside of food preparation. In medicine, proper doses of sodium nitrite can function as a bronchodilator, an intestinal relaxant, and even as an antidote to some poisons such as cyanide and hydrogen sulfide. It has also been used to dilate blood vessels and to treat certain lung disorders in infants.
As with any other chemical preservative, sodium nitrite has come under considerable scrutiny as its safety has been questioned. Certain laboratory studies have found links between large amounts of sodium nitrite consumption and a higher incidence of certain cancers. It has also been linked to migraine headaches in those who have a history of suffering from them. However, this chemical is also produced by our own bodies, and some say we make more of it than we consume. This is an important point to consider, since it plays a vital role in maintaining stomach health, specifically controlling the growth of bacteria that could otherwise lead to gastroenteritis.
The carcinogenic tendencies of sodium nitrite can be controlled or prevented by the addition of vitamin C to cured meats. Even so, some recommend that children and women who are pregnant or nursing should avoid any unnecessary intake of sodium nitrite. Like many controversial chemicals, it has not been conclusively proven to be a health hazard for humans in the amounts people are usually exposed to.
