Folic acid may protect against fetal heart defects, Quebec study suggests

Since Canada introduced mandatory fortification of grain products with folic acid more than a decade ago, the number of babies born with severe congenital heart defects has dropped significantly in Quebec, researchers say.

A McGill University study found a six per cent annual decline in cases of severe congenital heart defects in the province after 1998, when Canada began requiring food companies to add folic acid to products like flour and pasta.

' I think what we should do is try to encourage women to take the prenatal vitamins.' Dr. Gideon Koren

Folic acid is known to reduce the prevalence of spina bifida and other neural tube defects in newborns, but the new study adds weight to suspicions that the B vitamin plays a vital role in proper heart development as well.

Using provincial health databases, researchers identified all Quebec infants diagnosed with severe congenital heart defects between 1990 and 2005. Out of 1.3 million children born in the province during that period, 2,083 had a heart abnormality.

"We looked basically at the time trend to see whether the birth prevalence of severe congenital heart defects changed over time," said lead author Raluca Ionescu-Ittu, a PhD candidate working with McGill's congenital heart disease group.

"And immediately after the fortification, it was followed by a decrease in the birth prevalence," she said Tuesday from Montreal.

The authors, whose paper is published online Wednesday in the British Medical Journal, suggest the results are likely not the result of chance, because the timing of the decline coincides exactly with the introduction of fortification.

While the link between inadequate levels of the vitamin in women before and during pregnancy and the incidence of heart defects has not been proven, Ionescu-Ittu said the association is plausible.

And most other factors known to boost the risk of heart defects in babies among them older maternal age, medication use and obesity gradually increased over the study period, she said.

Yet there was still a drop in cases.

"This study is potentially very important," said Dr. Gideon Koren, head of the Motherisk program at Toronto's Hospital for Sick Children, who was not involved in the research.

Koren said an analysis done several years ago by his research group showed that mothers of children born with cardiovascular, brain or limb malformations reported taking less folic acid in multivitamins than mothers whose children had no birth defects.

"So there was an indirect proof for a potential effect," he said. "We do know that adequate amounts of folic acid do promote cell division and processes that lead to normal development. That goes without saying."

But Koren pointed out that one area of data is missing from the study that could skew its results. The researchers have included live births and stillbirths, but not pregnancy terminations, he said.

"The issue is that there are now more and more, year by year, people that because of in-utero ultrasound and echocardiograms may terminate pregnancy" after a severe birth defect is discovered in the fetus, Koren said.

Optimal dose unknown

However, a BMJ editorial suggests the effect of pregnancy terminations would not entirely cancel out the six per cent yearly drop in prevalence identified by the McGill researchers.

Ionescu-Ittu said more research is needed to pin down whether adequate folic acid levels in pregnant women can, in fact, prevent at least some cases of congenital heart defects in offspring and what daily dosage of the vitamin is optimal.

She said the cardiac abnormalities involve expensive, complex surgeries and other treatments, as well as causing often lifelong health problems for afflicted individuals and a tremendous strain for their families.

"Clearly the health burden is huge," agreed Koren, noting that Sick Kids research has shown that 40 per cent of pregnant women in Ontario do not take enough folic acid to be protective.

"So there's still a lot of improvement [needed]," he said. "We believe more women should receive higher doses I think what we should do is try to encourage women to take the prenatal vitamins."