Nitrates are used to preserve food such as bacon, ham, sausage, and cold cuts. [For the Dutch people: vlees beleg]
Most cold cuts are considered processed meats. The American Institute for Cancer Research defines processed meat as “meat preserved by smoking, curing or salting, or addition of chemical preservatives.”

Along with cold cuts, other processed meats include bacon, salami, bologna, hot dogs and sausages.
In the stomach with a high acidity nitrates are converted into nitrosamines, damaging chemicals which are also found in beer, some cheeses, and pickled fish.

Nitrosamines are potentially carcinogenic.[stomach,liver] They deplete the vitamin A stored in the liver, a dry skin may be a sign of overuse of nitrosamines[Rister]
Cut back on these foods to avoid as much as possible these nitrosamines.
By eating berries or cherries with the problematic nitrosamines the negative effects on the liver are reduced[Rister]