The risk of the most common type of congenital heart disease could be reduced with foods fortified with folic acid.
Adding folic acid to white flour, pasta, and cornmeal has been mandatory in Canada since 1998. Evidence of folic acid reducing neural tube defects, oral cleft, and cardiovascular anomalies led to the Government of Canada taking steps to help women of childbearing age increase the amount of folate they consume.
The United States Centers for Disease Control and Prevention (CDC) recommend that women take 400 micrograms of folic acid per day from at least 1 month before getting pregnant to prevent major birth defects of the baby's brain (anencephaly) and spine (spina bifida).
The research was conducted to determine if there is an association between food fortification with folic acid and birth prevalence of specific congenital heart defects (CHDs).
According to the study, there are approximately 650,000 to 1.3 million U.S. children and adults living with congenital heart disease. The most common type of defect in children is ventricular septal defects, which account for 620,000 of cases.
Previous studies have yielded inconsistent results for the effects of folic acid and folic acid food fortification on CHDs.
"Our study examined the effect of folic acid food fortification on each specific subtype of congenital heart disease based on the Canadian experience before and after food fortification was made mandatory in 1998," says Dr. K.S. Joseph, Ph.D., the study's senior author and professor in the Department of Obstetrics and Gynecology and the School of Population and Public Health at the University of British Columbia in Vancouver, Canada.
Effects of folic acid only evident in some subtypes of CHDs
Researchers analyzed data from almost 6 million births in Canada between 1990-2011 and controlled for influencing factors, such as maternal age, multiple births (twins, triplets), pregnancy complications, prenatal diagnosis, and pregnancy terminations.
Findings indicated that folic acid food fortification was associated with an 11 percent decrease in rates of congenital heart defects.
Dr. Joseph and colleagues also noted that the beneficial effects of folic acid were only observed in some types of CHDs. For example, there was a 27 percent reduction in conotruncal defects, or severe heart outflow tract abnormalities, and a 23 percent decrease in coarctation of the aorta, which is a narrowing of the major artery that carries blood to the body.
Also, a 15 percent reduction was seen in atrial and ventricular septal defects, which are the holes in the wall that separate the heart chambers. No change was observed concerning chromosomally associated defects - an abnormality in the number of an infant's chromosomes.
Dr. Joseph says that although the data is from Canada, the findings apply to the U.S. population, as the same fortification of foods with folic acid were implemented in the U.S. around the same time as Canada due to the North American Fair Trade Agreement of 1994.
The authors say:
"Our study shows associations between food fortification with folic acid and reductions in the birth prevalence of specific CHD subtypes. The associations were stronger for conotruncal defects and coarctation of the aorta and more modest for septal defects."
Dr. Joseph highlights the importance of taking folic acid for women who are trying to become pregnant, as they may not receive an adequate amount of folate from diet alone.
While food fortification with folic acid was aimed at reducing neural tube defects, the study shows that folic acid may also have a beneficial effect on specific types of CHDs, which are collectively more common.