Nitrates in and of themselves are not harmful, but what our body does with nitrates may or may not be dangerous to health. In the mouth, bacteria and other enzymes turn nitrates into nitrites. In turn, nitrites may form one of two different chemical compounds in the body: nitric oxide or nitrosamine. Nitric oxide is a chemical the body uses in specific concentrations and in specific tissues to derive benefit, notably by relaxing arteries, reducing blood pressure and improving circulation. Conversely, nitrosamines are associated with cancer, particularly along the gastrointestinal tract, including the esophagus, stomach, colon, and rectum.
So what decides the fate of the nitrites and whether they will be converted to nitric oxide or nitrosamines? Nitrates are found in many types of vegetables, such as celery. When ingested in vegetables, nitrates may be converted into nitric oxide, which can significantly improve cardiovascular health. Nitrites, however, form nitrosamines when they are subjected to high heat or when they enter an acidic environment in the presence of proteins. Nitrates and nitrites are commonly used to preserve processed meats such as hot dogs and bacon so the heat from a skillet, grill, or broiler can be the perfect laboratory for the production of nitrosamines. In addition, the acidic environment of the stomach can produce nitrosamines from cold processed meat.
Check labels to see if your package of smoked meat says, “No nitrates added.” Look for a disclaimer such as, “Except those occurring naturally in celery juice,” or something similar. Alternatively, there may be celery powder, celery juice, or celery salt listed in the ingredients panel. This is a deceptive tactic that the food companies use to hide nitrates. Even though celery juice is a source of nitrates, a product can contain celery juice and sport a “No nitrates added” label. The nitrate source is irrelevant. Nitrates + protein + high heat = nitrosamines.
The government has recognized the potential carcinogenic nature of nitrates and has issued two requirements on food suppliers. For one, food manufacturers are now required to limit the amount of nitrites and nitrates they use in processed meats. In addition, food manufacturers are required to add vitamin C to their products, which has been shown to inhibit nitrosamine formation. It would stand to reason, therefore, that if you ingest vitamin C with your bacon at breakfast, perhaps by taking a supplement or by drinking a glass of juice containing vitamin C, this will also help inhibit the production of nitrosamines. In general, processed meat eaten today contains much less nitrates and nitrites than it did a few decades ago. But even so, the World Health Organization recently declared processed meat as carcinogenic to humans due to nitrosamine formation as well as the formation of other toxic compounds during processing and digestion.