Faulty Folic Acid Assumptions: Prenatal Supplements Not Always a Good Idea
Hood, Ernie, Environmental Health Perspectives
Dietary folic acid supplementation in women of childbearing age has been a major public health success story, reducing the incidence of neural tube defects (NTDs) by an estimated 50-70%. The CDC currently recommends that all women of childbearing age eat a diet high in folic acid or take a daily multivitamin with 0.4 mg of folic acid each day, with higher intake from before conception through the first three months of pregnancy. In light of a new analysis of NTDs and folate pathway genes, however, that blanket recommendation may need to be fine-tuned [EHP 114:1547-1552; Boyles et al.].
If these results are confirmed, it appears there may be a subgroup of women in whom folic acid supplementation is actually positively associated with the formation of NTDs in their offspring--a startling finding the authors acknowledge to be counterintuitive. Counterintuitive or not, the study may have uncovered individuals susceptible to adverse outcomes stemming from overactivity in the folate metabolism pathway during a critical stage of embryonic neurodevelopment.
The researchers analyzed the genomes of 304 families where at least one individual had an NTD. They focused their analysis on 28 single-nucleotide polymorphisms (SNPs) in 11 genes known to be involved in the folate metabolism pathway, and stratified the genomic results by potential gene-gene interactions and by whether the mothers had taken folate-containing nutritional supplements prior to conception.
The results showed that certain SNPs in the betaine-homocysteine methyltransferase (BHMT) gene were significantly associated with NTDs, and that the significance was strongest with mothers who took folate supplements before conception. …