Pregnant women who take folic acid supplements may increase the risk of respiratory illness in their infants, according to an article released on December 2, 2008 in the Archives of Disease in Childhood, one of the BMJ Specialist Journals.

Folate, or folic acid, is also known as vitamin B9. In the United States and several other countries, flour is fortified with folic acid. This and other vitamins ask as methyl donors, which have an affect on the biochemical process of methylation, an integral part of genetic regulation.

Folate is presently recommended to pregnant women to mitigate the risk of congenital abnormalities. However, past research in mice has indicated that high levels of folic acid or similar substances in early pregnancy could increase the risk of allergic asthma, but this has not been verified in humans.

To determine the effects of folate supplementation in pregnant women, the researchers in this study examined more than 32,000 children born between 2000 and 2005 as part of the Norwegian Mother and Child Cohort Study up to the age of 18 months. In the examination, the mothers were surveyed regarding dietary habits, including supplements like folic acid, both before and after the birth.

Accounting for various factors that could confound the relationship between folate and respiratory complications, the infants with mothers who had taken folic acid supplements in the first three months of pregnancy had a higher risk of wheezing or respiratory functions in the first 18 months. This resulted in a 24% higher risk of admission to the hospital as a result of a respiratory infection.

The authors point out that methylation's impact on respiratory diseases and the immune system requires significant further research. However, they claim, recent investigation has suggested that it could have a key role in immune development, especially of T-cells. This, they speculate, could increase the chances of airway inflammation.

Folic acid supplements in pregnancy and early childhood respiratory health
SE Haberg, SJ London, H Stigum, P Nafstad, W Nystad
Online First Thorax 2008
doi: 10.1136/adc.2008.142448
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Anna Sophia McKenney