Bacteria May Help Thwart Allergies
Risk appears to be lower among people infected with H. pylori

(HealthDay News) -- Sometimes even the bad has a good side.

The bacteria Helicobacter pylori , known for causing stomach problems, including ulcers, appears to act in an opposite manner when it comes to allergic disease, researchers have found.

A study published in the Archives of Internal Medicine reported that people infected with a certain strain of H. pylori were less likely to have allergies or asthma.

" Helicobacter pylori has been found to be strongly associated with ulcer disease and stomach cancer, and there's a widespread belief that this organism is a pathogen," one of the study's authors, Dr. Martin Blaser, chairman of the Department of Medicine at New York University, told HealthDay .

But that belief started to change about a decade ago, Blaser said, when he and other researchers found there was an inverse relationship between having H. pylori and having the gastroesophageal reflux disease, a digestive disorder commonly called GERD.

The finding "raised the idea that helicobacter might be protective," he said. "It's bad for the stomach but good for the esophagus."

That led the researchers to hypothesize that H. pylori might also have an effect on asthma, because asthma has been linked to GERD.

To test the theory, they analyzed data from 8,000 adults and found that those with a particular strain of H. pylori , called CAG-positive, had a 21 percent decreased risk of asthma and a 23 percent lower risk of allergies.

"What we found was that if people ever had a history of asthma, there was an inverse association with CAG-positive helicobacter ," Blaser said, adding that when they broke the data down by age, they found a more "striking result." People who had been infected with CAG-positive H. pylori before they were 15 years old had a 37 percent lower risk of asthma, and the risk of allergies dropped by 45 percent.

"It's possible helicobacter is protecting against asthma to some degree, and, as it disappears, [possibly from antibiotic use], we're losing that layer of protection, which may explain why asthma, especially childhood asthma, is rising," Blaser said.

The prevalence of asthma jumped 75 percent from 1980 to 1994. Today, according to the American Association of Allergy, Asthma & Immunology, more than half of all Americans have at least one allergy.

An estimated 20 percent of people younger than 40 are infected with H. pylori , according to the National Institute for Diabetes and Digestive and Kidney Disorders.

Just what the study's findings eventually will mean for people with allergies and asthma and the doctors who treat them remains unclear.

"Medicine can be like a big jigsaw puzzle, and this may be a piece of that puzzle," Dr. Jane Krasnick, chief of allergy and immunology at St. John Macomb Hospital in Warren, Mich., told HealthDay . "Maybe right now, you notice this piece has fallen under a chair, and you wonder if it's important, so you go back to get that piece and keep it in a drawer in case you need it later."

On the Web

To learn more about the cause of allergies, visit the Asthma and Allergy Foundation of America.

SOURCES: HealthDay News ; Martin Blaser, M.D., Frederick H. King professor of internal medicine, chairman, Department of Medicine, and professor of microbiology, New York University School of Medicine, New York City; Jane Krasnick, M.D., chief of allergy and immunology, St. John Macomb Hospital, Warren, Mich.; April 23, 2007, Archives of Internal Medicine ; American Association of Allergy, Asthma & Immunology (www.aaaai.org)
Author: Serena Gordon
Publication Date: April 30, 2008
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