The Duke University Medical Center in Durham, N.C. study, published in the European Journal of Clinical Investigation, used mice to determine that minuscule amounts of gastric fluid in the lungs -- one of the effects of GERD -- may have an effect on the immune system in a way that may trigger asthma.

In laboratory experiments, mice exposed to gastric fluid in the lungs in a process mimicking micro-aspiration in humans developed what researchers call a T-helper type 2 response -- a type of immune system reaction characteristic of asthma. The mice exposed to allergens -- but not gastric fluid -- responded in what the researchers say is a more balanced manner -- an immune reaction consisting of both T-helper type 1 and T-helper type 2 responses.

"This is the first experimental evidence in a controlled, laboratory setting linking these two very common conditions in humans," study senior author Dr. Shu Lin said in a statement. "These data suggest that chronic micro-aspiration of gastric fluid can drive the immune system toward an asthmatic response."

However, the researchers stress, everyone who suffers GERD won't get asthma and the upside is GERD can be treated.