Stomach Germ May Protect Against Asthma

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Among children aged 3 to 19, the researchers found that those who harbored H. pylori reduced their risk of asthma by 25 percent.

"This is a new way of saying who's at risk for asthma and who's not," Blaser said. "You can't mess with Mother Nature. This bacterium that has been present forever in the human stomach has been disappearing, and that has consequences."

Some of the consequences are good, however, Blaser noted. These include the decline of ulcers and decreases in stomach cancer among adults, he said. "But these are diseases of old age," he said. "It is possible that H. pylori may be protective of children, but bad for old people."

The study findings were published online July 15 in The Journal of Infectious Diseases.

Dr. Clifford Bassett, medical director of Allergy and Asthma Care of New York in New York City, thinks the findings open a new window on doctors' understanding of asthma and allergies.

"It appears this will add to our knowledge and research looking at incidence and prevalence of asthma and allergic diseases in children and adults in an increasingly sanitized world," he said. "The relevance of H. pylori as a potential risk in asthma is quite thought-provoking by any means."

More information

For more on asthma, visit the U.S. National Institutes of Health.