THURSDAY, Sept. 18, 2008 (HealthDay News) -- Increasing use of folic acid and other dietary supplements by women may be one reason why the prevalence of asthma has nearly doubled in the past 25 years, U.S. researchers are suggesting.
They found that a pregnant woman's diet can cause gene regulation (epigenetic) changes that increase an offspring's risk of developing allergic asthma.
The study, by researchers at National Jewish Health and Duke University, found that pregnant mice fed diets high in supplements containing methyl-donors (folic acid, L-methionine, choline and genistein) had babies with more severe allergic airway disease than mice born to mothers that consumed diets low in methyl-containing foods.
The mice born to mothers fed high methyl-donor diets had greater asthma severity, more airway hyperactivity, more allergic inflammation in the airways, higher levels of IgE in their blood, and their immune system T-cells were more likely to be the type associated with allergy. Male offspring also transmitted a higher predisposition to allergy airway disease to their pups.
There was no link between high methyl-donor diets during lactation or adulthood and increased risk of allergic asthma, the researchers said.
The study was published online Sept. 18 in the Journal of Clinical Investigation.
"Our findings suggest that a mother's diet that alters DNA methylation can affect the development of the fetus's immune system, predisposing it to allergic airway disease," senior author Dr. David Schwartz, a professor of medicine at National Jewish Health, said in a news release.
"It also suggests the dramatic increase in asthma during the past two decades may be related in part to recent changes in dietary supplementation among women of childbearing age," he added.
"There seems to be a crucial stage, during development in utero, when a young mouse is susceptible to epigenetic changes that can alter its immune system," study co-author John W. Hollingsworth, assistant professor of medicine at Duke University School of Medicine, said in the news release.
"These epigenetic changes may partially explain why it has been so difficult to definitively identify genes that contribute to asthma risk; the effect of genetic variations can be masked or further complicated by epigenetic changes," he noted.
The U.S. Centers for Disease Control and Prevention has more about asthma.