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You shouldn’t be concerned about nitrates & nitrites in bacon. 

It may surprise you to learn that the vast majority of nitrate/nitrite exposure comes not from food, but from endogenous sources within the body. (1) In fact, nitrites are produced by your own body in greater amounts than can be obtained from food, and salivary nitrite accounts for 70-90% of our total nitrite exposure. In other words, your spit contains far more nitrites than anything you could ever eat.

When it comes to food, vegetables are the primary source of nitrites. On average, about 93% of nitrites we get from food come from vegetables. It may shock you to learn that one serving of arugula, two servings of butter lettuce, and four servings of celery or beets all have more nitrite than 467 hot dogs. (2) And your own saliva has more nitrites than all of them! So before you eliminate cured meats from your diet, you might want to address your celery intake. And try not to swallow so frequently.

All humor aside, there’s no reason to fear nitrites in your food, or saliva. Recent evidence suggests that nitrites are beneficial for immune and cardiovascular function; they are being studied as a potential treatment for hypertension, heart attacks, sickle cell and circulatory disorders.

It’s important to understand that neither nitrate nor nitrite accumulate in body. Ingested nitrate from food is converted into nitrite when it contacts our saliva, and of the nitrate we eat, 25% is converted into salivary nitrite, 20% converted into nitrite, and the rest is excreted in the urine within 5 hours of ingestion. (3) Any nitrate that is absorbed has a very short half-life, disappearing from our blood in under five minutes. (4) Some nitrite in our stomach reacts with gastric contents, forming nitric oxide which may have many beneficial effects. (5, 6) 

http://chriskresser.com/the-nitrate-and-nitrite-myth-another-reason-not-to-fear-bacon