Sodium nitrite is a salt that helps to prevent bacterial cultivation of foods. Consequently, it's used as a preservative, especially in meats. You may have heard that it's not good for your health; this is true -- sodium nitrite can lead to formation of cancer-causing molecules that can result in tumor formation, and that can move across the placenta.
Sodium Nitrite
Sodium nitrite has the chemical formula NaNO2. It's not the same as the similar-sounding sodium nitrate, NaNO3, but the two can convert into one another in the body, meaning that everything that results from nitrate consumption also results from nitrite consumption, and vice versa. Nitrites were originally used to help reduce the possibility of food poisoning. Particularly when they're in combination with sodium chloride -- table salt -- nitrites very effectively prevent bacteria from colonizing foods.
Nitrosamines
The major concern with regard to sodium nitrite is that it reacts with compounds called secondary amines to produce substances called nitrosamines. Nitrosamines, in turn, are potent carcinogens, meaning they cause cancer. Secondary amines are not only common in the body, they're found in foods as well -- the amino acids that make up proteins are all secondary amines. As such, when you consume meat that is preserved with sodium nitrite, you're eating the ingredients necessary to make nitrosamines.
Tumors
Nitrites have been linked to increased risk of cancer, through production of nitrosamines, explains the Linus Pauling Institute. Further, specific nitrosamines appear to lead to cancer in certain parts of the body; some favor liver cancer, while others gravitate toward lung cancer. There's some indication that vitamin C helps prevent formation of nitrosamines through the reaction of nitrites with secondary amines. As a result, cured meats often contain large quantities of added vitamin C.
Pregnancy
During pregnancy, nitrites may be of particular concern, as they have been demonstrated to cross the placenta and lead to increased risk in tumors in children, notes Dr. Susan Preston-Martin and colleagues in a 1982 article in the journal Cancer Research. Further, nitrites crossing the placenta can result in formation of methemoglobin, a form of the protein hemoglobin that carries oxygen from the lungs to the tissues. Methemoglobin isn't as effective at delivering oxygen, which can negatively impact fetal health.
References
- Linus Pauling Institute: Nitrosamines
- Cancer Research; N-Nitroso Compounds and Childhood Brain Tumors: a Case-Control Study; Susan Preston-Martin, et al; 1982
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