Since Canada began fortifying grain products with folic acid, the number of babies born with severe congenital heart defects in Quebec has dropped significantly, researchers have found.
The study, published online in the British Medical Journal, found that the number of babies born with severe congenital heart defects has fallen every year by six per cent since 1998. That was the year Canada began requiring food companies to add folic acid to products like bread and pasta.
By contrast, there was no change in the prevalence of severe birth defects in the nine years before fortification, the researchers from McGill University found.
Rates of neural tube birth defects, such as spina bifida, have plummeted since folic acid supplementation began in Canada, as have rates of some childhood cancers such as neuroblastoma.
To see whether rates of congenital heart defects were falling as well, researchers led by PhD candidate Raluca Ionescu-Ittu, reviewed Quebec health databases and identified all infants diagnosed with heart defects between 1990 and 2005.
Out of 1.3 million children born during that period, 2,083 had a heart abnormality. But the incidence rate dropped off significantly after 1998, the team found.
Whether the addition of the vitamin in the diets of expectant mothers caused the incidence of heart defects to fall has not been proven, Ionescu-Ittu noted. But she said the association is plausible.
She says her findings are likely not the result of chance, because the timing of the decline coincides so precisely with the introduction of fortification.
What's more, 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.
A BMJ editorial adds that the effect of increased pregnancy terminations would not entirely cancel out the six per cent yearly drop in prevalence identified by the McGill team.
Ionescu-Ittu said more research is needed to pin down whether adequate folic acid levels in pregnant women can prevent some cases of congenital heart defects, and what daily dosage of the vitamin is optimal.
Health Canada recommends all women of childbearing age take 0.4 mg of folic acid a day. It adds that taking more than 1 mg a day of folic acid without the advice of a doctor is not recommended.
Currently 67 countries fortify wheat flour, including 47 that make it mandatory for manufacturers to fortify.
"Our study offers new evidence regarding the benefits of the mandatory fortification policy, which is important both for the countries that are currently considering starting such a policy and for the countries that have already implemented it and are currently monitoring and evaluating its implementation," said Ionescu-Ittu.
