Increasing the dietary intake of folate: pros and cons.

Studies providing unambiguous evidence that the occurrence and recurrence of pregnancies complicated by neural tube malformations were reduced by folic acid supplementation at the time of conception have prompted the Food and Drug Administration (FDA) to approve the fortification of cereal-grain products with this vitamin. Additional enthusiasm for this decision has emanated from studies that show an association of hyperhomocysteinemia with vascular disease and neural tube defects. Despite the apparent logic for the folic acid food fortification program, there are some concerns about the danger of such a policy to segments of the public who have unrecognized vitamin B12 deficiency because folate can mask the hematologic abnormalities and allow the neurological complications to progress or even accelerate. Thus, the apparent benefits of the folic acid fortification and the potential dangers of such a program have polarized opinions in favor of (pro) and in opposition to (con) this FDA policy. The purpose of this review is to present the evidence on which each of these two groups base their opinions.