Spina bifida, folate metabolism, and dietary folate intake in a Northern Canadian aboriginal population.

OBJECTIVES Inhabitants of the subarctic region of the Eastern James Bay of Northern Quebec consume a diet low in folate. This is largely secondary to poor access to plant-foods and a preferred diet high in meat, fowl, and fish as in many other northern populations. Furthermore, there is a high frequency of spina bifida in the Cree of the region. It was hypothesized that genetically altered folate metabolism as well as low folate intake contributes to the high frequency of spina bifida. METHODS A case-control study evaluating folate metabolism and the common 677C-T polymorphism of the gene for methylenetetrahydrofolate reductase (MTHFR) in mothers of children with spina bifida, and controls (n=23) of Cree descent from the Eastern James Bay region. These results were compared to a similar Montreal cohort (n=152) who were not of First Nations descent. Dietary intake of folate of 219 women of the Eastern James Bay region was also determined. RESULTS No Cree mothers of children with spina bifida were homozygous for the 677C-T polymorphism of MTHFR. Although serum cobalamin was significantly higher in Cree mothers, RBC folate was significantly lower than in the Montreal cohort. In addition, plasma homocysteine was significantly lower in the Cree. Dietary intake of folate of women in the same region was substantially lower (100 microg/day) than widely recommended daily intakes. CONCLUSIONS In this remote Canadian aboriginal community there is no evidence of altered folate metabolism in the mothers of children with spina bifida. Nonetheless, it remains essential that culturally appropriate public health efforts be continued to increase the intake of folic acid in the hope of reducing the high frequency of spina bifida in this population.