Then, soil over-exploitation causes the use of chemical fertilizers like the widely used based on nitrates. As nitrates pass to the organism, in some circumstances they could be converted to nitrites inside the body. Finally, if other chemical compound, secondary amines, are there for interacting, there's a chance of nitrosamine creation. These are dangerous as they could create an abnormal cell division and a great problem with it.
Sometimes, nitrosamines don't proceed from the aforementioned cycle but as a “natural product” of different methods of cooking aliments, specially with high temperatures and oil. Also, tobacco has a great quantity of them. It could be possible that beer, cheese or fish could have certain quantities of nitrosamines if those compounds were present to react in the raw materials. There's not the first time that meat, fish or cheese were treated with nitrites for conservation purposes so be warned!
If you take water and salt, they can be mixed and the product could attack metals. It's a direct consequence, and the same for nitrites, amines and nitrosamines and potential effects. But there's at least two options.
First, the most recommendable one, is to evolve and avoid nitrites in the food chain, and find other substitutes for conservation and fertilization, establishing controls and security. Nitrites aren't dangerous by themselves, but amines are very common. This path is right now being walked in some areas. And second, to use a kind of antagonist that could prevent the formation of nitrosamines or block their activity. This is ascorbic acid, or with other words, vitamin C.
Any person should take this information in consideration and think when there are surely some nitrosamines on the plate or after some food mix. Then, perhaps not a bad idea to take some citric or other vitamin C source even if the digestion could be better without it!