According to Swedish researcher, Joel Petersson, this occurs because nitrates are converted into nitrites by bacteria in the mouth. This means that antibacterial mouthwashes may also be harmful for the stomach.
Laboratory work on animals has shown that nitrate additives in food protect against both gastric ulcers and the damage to the stomach that is done by taking anti-inflammatory drugs. The bacteria in the oral cavity are very important to the process of nitrates in food protecting the stomach's mucous membrane. This has been examined in rats that have been given nitrate-rich feed, where some of them have also simultaneously received an antibacterial oral spray. When these rats were then given anti-inflammatory drugs, damage to the mucous membrane only occurred in the ones that had received the oral spray. In the latter the nitrates no longer had a protective effect on the mucous membrane, as the oral spray had killed the important bacteria that normally convert nitrates into nitrites.
According to Petersson, if we all ate the recommended 500 g of vegetables and fruit each day, we would have fewer stomach problems.
