Newborns with high levels of unmetabolized folic acid had a higher risk for food allergy later in childhood than newborns with lower circulating folic acid levels -- suggesting that increased exposure to synthetic folic acid in utero could be a risk factor for food allergy.
In a nested case-control study performed using data from the Boston Birth Cohort, mean folate levels at birth were found to be lower among children who went on to develop food allergies, while mean levels of unmetabolized folic acid were higher.
The research was presented here at the joint meeting of the American Academy of Allergy, Asthma & Infectious Disease (AAAAI) and the World Allergy Organization (WAO).
"Food allergy prevalence seems to be increasing, and it has been hypothesized that increased [in utero] folic acid exposure may be a central contributor to this," said study co-author Corinne Keet, MD, PhD, of Johns Hopkins Hospital in Baltimore.
In a press conference at the meeting Keet said early research suggests that unmetabolized folic acid could have a negative impact on health. In the early 1990s folic acid was found to be protective of neural tube birth defects, and in 1998 the U.S. mandated the fortification of flour and other grain products with folic acid. Supplementation with 400 micrograms of folic acid is also recommended for women in their childbearing years.
"When the synthetic form of folate is metabolized, only a certain amount is able to be processed through the normal pathways, and the excess circulates as unmetabolized folic acid," Keet said.