You've likely heard that there are a number of foods you should avoid during pregnancy because they have the potential to harm your developing baby. Foods that contain sodium nitrite, a common preservative, are among these. Because nitrites can cross the placenta, it's best to avoid them entirely during pregnancy. Further, nitrite consumption has been linked to a number of unhealthy consequences in both adults and developing babies.
Nitrite Chemistry
Sodium nitrite is a salt composed of positively charged sodium particles and negatively charged nitrite particles, where a nitrite particle has the chemical formula NO2. Sodium nitrite is a common meat preservative, as is the related salt sodium nitrate. In conditions such as those encountered in the body, nitrate converts into nitrite, meaning that if you're avoiding nitrites, you need to avoid nitrates as well to be safe.
Nitrite Consequences
Nitrites --- and by extension, nitrates --- react with chemicals called secondary amines to produce powerful carcinogens, or cancer-causing agents. Secondary amines are quite common in the body; they're components of all proteins. Further, since sodium nitrite is used as a meat preservative and since meat consists of protein, meat preserved with sodium nitrite contains all the necessary components to produce nitrosamines, the carcinogens that come from nitrites, explains the Linus Pauling Institute.
Nitrites and the Placenta
Animal studies show that nitrites can cross the placenta, which is the organ that allows nutrients and oxygen to pass from your bloodstream into your baby's. Once nitrites have found their way across the placenta, they can react with proteins in your baby's body, leading to increased risk of cancer. A 1996 article by Dr. S. Preston-Martin and colleagues in the journal "Cancer Epidemiology, Biomarkers, and Prevention" notes that nitrite consumption by pregnant women increases a baby's risk of developing tumors later in life.
Other Concerns
Another possible reaction of nitrites in the body involves hemoglobin, the protein that makes up red blood cells and helps them deliver oxygen to the tissues. When nitrites react with hemoglobin, they result in formation of methemoglobin, which doesn't deliver oxygen efficiently. A 1973 study published by Dr. N. Gruener and colleagues in the "Bulletin of Environmental Contamination and Toxicology " notes that animal studies show formation of methemoglobin in developing fetuses as a result of maternal nitrite consumption.
References
- Linus Pauling Institute: Nitrosamines
- "Cancer Epidemiology, Biomarkers, and Prevention"; Maternal consumption of cured meats and vitamins in relation to pediatric brain tumors; S. Preston-Martin et al; August 1996
- "Bulletin of Environmental Contamination and Toxicology"; Methemoglobinemia induced by transplacental passage of nitrites in rats; N. Gruener et al; 1973
