The incidence of the heart problems was reduced by 6 per cent following mandatory fortification of grain products, introduced in Canada in 1998, researchers from McGill University and the University of Alberta report in the British Medical Journal.
“Our population based study shows that fortification of grain products with folic acid in Canada was followed by a significant decrease in the birth prevalence of severe congenital heart defects, supporting the hypothesis that folic acid intake in the period around conception reduces the birth prevalence of severe congenital heart defects,” wrote the researchers, led by Louise Pilote.
Folic acid and NTDs
Folate is found in foods such as green leafy vegetables, chick peas and lentils. Folic acid - the synthetic, bioavailable form of folate – is obtained from grain products in the US and Canada following introduction of mandatory fortification in 1998.
Currently, supplementation with folate and folic acid is recommended to all women of child-bearing age since most neural tube defects (NTDs), including spina bifida and anencephaly, occur within the first 22 to 28 days of pregnancy, when the mother-to-be is not aware she is even pregnant.
Folic acid supplements after this time are too late to prevent neural tube defects and therefore fail to benefit women with unplanned pregnancies - more than half of all pregnancies in the US.
Preliminary evidence indicates that the 1998 introduction of public health measures in the US and Canada has reduced the incidence of NTDs by 15 to 50 per cent. In Chile, the measure has been associated with a 40 per cent reduction in NTDs. Parallel measures in European countries, including the UK and Ireland, are still on the table.
In March, a Food Safety Authority of Ireland (FSAI) working group stated there would be no public health benefit from mandatory folic acid fortification, but a final determination would be made at the end of the year when more data would be available.
The new study looked at data from infants born between 1990 and 2005 in Quebec. Out of the 1,324,440 infants born, 2,083 had a congenital heart defects. This is equivalent to an average birth prevalence of 1.57 out of every 1,000 births, said the researchers.
Analysis of the data showed no change in the prevalence of severe birth defects in the nine years before fortification, but a 6 per cent reduction in the prevalence in the seven years after fortification, wrote the researchers.
“An average 6.2 per cent reduction per year in the birth prevalence of severe congenital heart defects observed in this study might seem modest,” wrote the researchers. “However, given that severe congenital heart defects require complex surgical interventions in infancy and are associated with high infant mortality rates, even a small reduction in the overall risk will significantly reduce the costs associated with the medical care of these patients and the psychological burden on patients and their families,” they added.
Commenting on the mechanism, Pilote and her co-workers stated that the B vitamin may have a beneficial role in the early development of an embryo's circulatory system, ensuring correct formation of the heart.
In an accompanying article from Helena Gardiner and Jean-Claude Fouron from Imperial College at Queen Charlotte’s and Chelsea and the Royal Brompton Hospitals, and CHU Sainte-Justine in Montreal, respectively, said that population-wide measures of fortification should be followed, but rather targeting of women of child bearing age.
Commenting independently on the research, Dr Sian Astley, a scientist for the Institute of Food Research, told the BBC: "Personally, I do not think mandatory fortification is the way forward. It is like using a sledge hammer to crack a nut.
"It would reduce ill health in children but there are cautionary issues.
"An alternative would be to fortify only certain foods and clearly label them so consumers can make the choice. Co-fortification with other B vitamins would be another sensible option," she added.
Source: British Medical Journal 2009, Volume 338:b1673, doi:10.1136/bmj.b1673“Prevalence of severe congenital heart disease after folic acid fortification of grain products: time trend analysis in Quebec, Canada” Authors: Raluca Ionescu-Ittu, A.J. Marelli, A.S. Mackie, L. Pilote
Editorial: British Medical Journal 2009, Volume 338: b1144, doi:10.1136/bmj.b1144“Folic acid fortification and congenital heart disease” Authors: H.M Gardiner, J.C. Fouron