Food nitrates have long been linked to an increased cancer risk, however the new study from Uppsala University has suggested that nitrate-rich vegetables such as spinach, lettuce, radishes and beetroot have a positive affect on the stomach by activating the mucous membranes' own protective mechanisms, thus reducing the risk of problems such as gastric ulcers.

In the body, blood circulation transports nitrates to the salivary glands, where they are concentrated. When we have eaten nitrate-rich food our saliva thus contains large amounts of nitrates, which the bacteria of the oral cavity partially convert into nitrites.

When we swallow the nitrites they come into contact with acid gastric juice, and are then converted into the biologically active substance nitric oxide.

This results in our developing high levels of nitric oxide in the stomach after eating vegetables.

The study led by Joel Petersson of Uppsala University's Department of Medical Cell Biology showed that the nitric oxide that is formed in the stomach stimulates the protective mechanisms of the mucous membrane.

Two such important defence mechanisms are the stomach's constant renewal of the mucous layer that covers the mucous membrane and its maintenance of a stable blood flow in the mucous membrane.

The research conducted using animal models revealed that nitrate additives in food protect against both gastric ulcers and the minor damage that often occurs in the gastrointestinal tract as a result of ingestion of anti-inflammatory drugs.