Studies Suggest Mother's Diet Affects Child's Risk of Asthma 
The prevalence of asthma has nearly doubled over the past several decades, but physicians and scientists have struggled to explain why. New research at National Jewish Health suggests that a pregnant mother's diet can increase the chance her offspring will develop allergic asthma.
David Schwartz, MD, Professor of Medicine and Director of the Center for Genetics and Therapeutics at National Jewish Health, led the experiments, which highlight an emerging area of science known as epigenetics, and its potential role in asthma and other chronic lung diseases. Moreover, this groundbreaking work suggests that dietary supplements taken during pregnancy, including folic acid, may contribute to the development of asthma.
Epigenetics involves small molecules that bind to the DNA. Although these molecules do not alter the genetic code, they do alter how genes are expressed. Like the DNA code, these molecules can be inherited. A variety of environmental factors, including diet, tobacco smoke, and medications can induce epigenetic changes to DNA.
Dr. Schwartz and his colleagues fed pregnant mice diets high in "methyldonors," substances with an abundance of methyl groups (CH3) capable of causing epigenetic changes. The offspring of the pregnant mice fed these diets were more likely to have asthma. Folic acid, a dietary supplement taken by millions of pregnant women to reduce the risk of birth defects, was one of those methyl-donors.
"Our findings suggest that a mother's diet can affect the development of the fetus's immune system," said Dr. Schwartz. "When the diet is high in methyl-donors, such as folic acid, it may predispose it to allergic airway disease. Our research also suggests that the dramatic increase in asthma during the past several decades may be related in part to recent changes in dietary supplementation among women of childbearing age."
Given the important role that folic acid has played in prevention of birth defects, Dr. Schwartz does not advise any changes in folic acid supplementation, but he does believe the issue is worth further vigorous investigation.
