The findings of a research team at the Humanitas Institute in Milan are to be published in the journal Gastroenterology, the Italian news agency Ansa reported.

The scientists say that the stomach lining helps keep out bacteria that cause Crohn's, an inflammation that can involve any part of the digestive tract from the mouth to the anus. They found that patients with Crohn's and similar diseases have low levels of a protein known as JAM-A in their stomach linings.

''This lack permits the passage of toxic substances and bacteria that get into the mucous layers and increase inflammation,'' said Silvio Danese said, head of the research team.

About 4 million people worldwide are believed to suffer from chronic intestinal diseases.