Ulcer-Causing Bacteria May Prevent Asthma

H. pylori might also protect against allergies, study says.

By Serena Gordon
HealthDay Reporter
Monday, April 23, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

MONDAY, April 23 (HealthDay News) -- The bacteria responsible for many peptic ulcers, Helicobacter pylori, may not always act in a damaging way. Instead, new research suggests that the germs may actually protect against asthma and allergies.

Using data from almost 8,000 adults, researchers from New York University School of Medicine found that people infected with a particular strain of H. pylori had a 21 percent decreased risk of having asthma and a 23 percent decreased risk of allergies compared to people without the bug. What's more, the researchers found that when the infection with H. pylori occurred before the age of 15, the odds of having asthma were reduced by 37 percent, and the odds of allergies were reduced by 45 percent.

" 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," said the study's co-author, Dr. Martin Blaser, chairman of the department of medicine and a professor of microbiology at NYU.

But, about 10 years ago, Blaser said, he and other researchers looked at H. pylori's association with another common digestive disorder, gastroesophageal reflux disease (GERD), and found that there was an inverse relationship between having H. pylori and having GERD. That finding "raised the idea that helicobacter might be protective. It's bad for the stomach, but good for the esophagus."

As many as one in five people under age 40 is infected with H. pylori, according to the National Institute for Diabetes and Digestive and Kidney Disorders. Yet, not everyone who's infected develops an ulcer.

Because H. pylori appeared to be protective against GERD, and previous research had linked GERD and asthma, Blaser and his colleagues wondered if H. pylori might protect against asthma as well.

To evaluate this theory, Blaser and his colleague, Yu Chen, culled data from the Third National Health and Nutrition Examination Survey about asthma and allergy history for 7,663 adults. The researchers also assessed whether the study volunteers had evidence of strains of H. pylori called CAG positive or CAG negative in their blood.