According to research from the Johns Hopkins Children's Center, folic acid, or vitamin B9, essential for red blood cell health and long known to reduce the risk of spinal birth defects, may also suppress allergic reactions and lessen the severity of allergy and asthma symptoms.

Asthma affects more than 7 percent of adults and children in the United States, and is the most common chronic condition among children, according to the Centers for Disease Control and Prevention. Environmental allergies are estimated to affect 25 million Americans, according to the CDC.

In what is believed to be the first study in humans examining the link between blood levels of folate, the naturally occurring form of folic acid, and allergies, the scientists say results add to mounting evidence that folate can help regulate inflammation. Recent studies have found a link between folate levels and inflammation-mediated diseases, including heart disease.

Image: A ball and stick model of folic acid, also known as folacin or vitamin B9.

Reviewing the medical records of more than 8,000 people ages 2 to 85 the investigators tracked the effect of folate levels on respiratory and allergic symptoms and on levels of IgE antibodies, immune system markers that rise in response to an allergen. People with higher blood levels of folate had fewer IgE antibodies, fewer reported allergies, less wheezing and lower likelihood of asthma.

"Our findings are a clear indication that folic acid may indeed help regulate immune response to allergens, and may reduce allergy and asthma symptoms," says lead investigator Elizabeth Matsui. "But we still need to figure out the exact mechanism behind it, and to do so we need studies that follow people receiving treatment with folic acid, before we even consider supplementation with folic acid to treat or prevent allergies and asthma."

The current recommendation for daily dietary intake of folic acid is 400 micrograms for healthy men and non-pregnant women. Many cereals and grain products are already fortified with folate, and folate is found naturally in green, leafy vegetables, beans and nuts.

Other findings of the study:

Blacks and Hispanics had lower blood folate levels, 12 and 12.5 nanograms per milliliter, respectively, than whites (15 ng/ml), but the differences were not due to income and socio-economic status.

Cautioning that it's far too soon to recommend folic acid supplements to prevent or treat people with asthma and allergies, the researchers emphasize that more research needs to be done to confirm their results, and to establish safe doses and risks.

The Hopkins team is planning a study comparing the effects of folic acid and placebo in people with allergies and asthma.
References:
1. Elizabeth Matsui, et al. Johns Hopkins Medical Institutions.