The stomach bacterium Helicobacter pylori, which causes stomach cancer and peptic ulcers, may not be all bad. According to a new study, it may help protect kids from asthma.
The study, based on an analysis of a health survey of 7,663 adults, showed that a virulent strain of H. pylori was especially associated with being asthma-free before the age of 15.
People who carry the strain were 40 percent less likely to have had asthma at an early age than those who didn?t carry the strain. The study also found that the microbe was associated with protection against ragweed and other allergies due to pollens and molds particularly among younger adults.
The study is published in the April 23, 2007, issue of Archives of Internal Medicine.
“Ultimately, the potentially protective properties of Helicobacter are consistent with one another,” explains Martin J. Blaser, M.D., the Frederick H. King Professor of Internal Medicine, Chairman of the Department of Medicine, and Professor of Microbiology at NYU School of Medicine, who has been studying H. pylori for more than 20 years.
“These properties point toward a much more complex view of the organism?not just as ulcer-pathogen or cancer-pathogen, but as an organism that has its costs and benefits to us,” says Dr. Blaser. “The relative costs and benefits clearly differ among individuals.”
Dr. Blaser performed the study with Yu Chen, Ph.D., MPH, assistant professor in the Department of Environmental Medicine at NYU School of Medicine, a new faculty member with expertise in epidemiology.
H. pylori lives in the mucous layer lining the stomach where it persists for decades. It is acquired usually before the age of 10, and is transmitted mainly in families. Dr. Blaser?s previous studies have confirmed the bacterium?s link to stomach cancer and elucidated genes associated with its virulence, particularly a gene called cagA.
Over recent years, Dr. Blaser began to suspect that the organism, the dominant bacteria in the stomach, may play a role in human health as well as disease. This observation, he says, is consistent with a theory called the hygiene hypothesis. It suggests that exposure to microbial infections in early childhood prevents or diminishes the development of allergies and asthma.
“No one would have predicted that the presence or absence of bacteria in your stomach is associated with your sensitivity to pollens and molds,” says Dr. Blaser. “But now we have that observation and we can begin to construct a model. One hypothesis is if you have H. pylori in your stomach, you have an inflammatory process that is on-going for decades, and this is skewing the immune response in a particular direction.”