Low Levels of Vitamin B12 May Increase Risk for Neural Tube Defects
Children born to women who have low blood levels of vitamin B12 shortly before and after conception may have an increased risk of a neural tube defect, according to recent analysis.
Hightower: A new study shows that babies born to women who have low levels of vitamin B12 may have an increased risk of a neural tube defect, a class of birth defects affecting the brain and spinal cord. Dr. James L. Mills of the National Institute of Child Health and Human Development explains that the brain and the spinal cord are formed when a portion of the embryo folds into a tube.
Mills: And when that folding fails to be completed, and doesn't close, then you can get a major defect in either the brain or the spinal cord. And these are both very devastating defects.
Hightower: One type of defect, spina bifida, can cause partial paralysis and the other is a fatal defect in which the brain and skull are severely underdeveloped. Dr. Miller says a major discovery a few years ago was that a lot of neural tube defects could be prevented by taking folic acid.
Mills: And B12 is very closely related to folic acid biochemically, and they are involved in one key reaction. And it's been shown several times previously that people who have children with neural tube defects have lower vitamin B12 levels during pregnancy. So we wanted to pursue that, and find out just how high a level of B12 you needed to be protected from that risk.
Hightower: Dr. Mills says the risk, or incidence rate for neural tube defects is about one per 2,000 live births.
Mills: Now, it used to be one per thousand, and folic acid fortification of food has lowered the rate dramatically.
Hightower: For this study, NIH scientists collaborated with researchers in Ireland, a country with a high rate of neural tube defects.
Mills: In fact, they call it "The Curse of the Celts," there, and it's probably partially genetic, and partially because of diet. So we have been doing research there, because it's an area where they have a lot of people with the problems, and it enabled us to find women who were not exposed to a lot of supplements that contained either folic acid or B12.
Hightower: Dr. Mills points out that the U.S. Public Health Service recommends that all women of childbearing age consumer 400 micrograms of folic acid each day, ensuring adequate stores of the vitamin in the event of an unintended pregnancy. He emphasizes the importance of B12 as well.
Mills: The point that we're making in our study, that's new, is that women also should be aware of the fact that they need adequate B12. And two groups of women are at risk: those who are vegans, who may not be getting B12 in their diets; and women who have an absorption problem, any gastrointestinal problem that can interfere with vitamin absorption. And their physician should be able to tell them if they are at risk.
Hightower: For more information about neural tube defects and this study, visit the NICHD website at www.nichd.nih.gov. This is Dorie Hightower, National Institutes of Health, Bethesda, Maryland.