Congenital heart defects in Canadian Inuit: is more folic acid making a difference?

INTRODUCTION

Grain fortification of flour with folic acid has successfully reduced neural tube defects (NTDs) by approximately one half of the pre-fortification rate. The knowledge that the use of multivitamins with folic acid has also been shown to reduce some birth defects has prompted interest in determining whether folic acid may also play a role in the prevention of non-neural tube defects. Although NTDs are not more frequent in the Inuit of the Eastern Arctic, septal heart defects, were documented pre-fortification (1989-1994) to be increased 4 fold.

OBJECTIVES

To determine if current efforts of fortification are sufficient and to explore other genetic/ environmental determinants of the increased rate of septal heart defects in the Eastern Arctic.

METHODS

Inuit mothers of children from communities on Baffin Island with and without heart defects were invited to participate in a case control study evaluating nutrient intake, pregnancy exposures, RBC folate, serum cobalamin, homocysteine, and functional polymorphisms for genes important in folate metabolism and uptake.

RESULTS

41 children with isolated heart defects and their mothers with 36 community matched Inuit controls have entered the study to date.

RESULTS

There were no differences in RBC folate (953 Vs 922 nmol/L p = .49), serum cobalamin, and homocysteine, between mothers of cases and controls. The combined average RBC folate for the women ages 18-45 was 947 +/- 32 nmol/L. There was no difference between any documented alcohol (H"30%) and cigarette (H"82%) use in pregnancy. No Inuit women were taking vitamins at conception or at the time of this study. The results of the genetic studies will be reported elsewhere.

CONCLUSIONS

RBC folate (post-fortification) in our sample of women of childbearing years is reassuring. However, it is possible that pre-fortification levels combined with genetic predisposition may have previously influenced the high rate of heart defects. Follow-up study is underway to determine if rates of heart defects have decreased since fortification was commenced. Since folate alone may not be sufficient to reduce non-neural tube defects, culturally appropriate public health efforts need to be initiated to encourage multivitamin use periconceptionally.