Sept. 7, 2007 - Americans' folate levels have dropped -- but not yet to the low levels that lead to birth defects, the CDC reports.
Perhaps the worst consequences come when pregnant women have folate deficiency. Their unborn children are at risk for neural tube defects. These birth defects result in spina bifida (an incompletely formed spinal cord ) or anencephaly (in which a large part of the child's brain and skull are missing).
To prevent birth defects, the U.S. has since 1998 required enrichment of cereal-grain products with folate. Pregnant women were encouraged to eat folate-rich foods and/or folate supplements (nearly all multiple vitamins contain the minimum daily recommended dose of folate).
The strategy worked. Americans' folate levels soared, and neural-tube defects became rarer.
But now Americans' folate levels are dropping, the CDC says. Fortunately, U.S. folate levels still are high enough to prevent folate deficiency.
"The decrease is not at the low end of concentrations and therefore does not raise concerns about inadequate status," conclude CDC researcher Christine M. Pfeiffer, PhD, and colleagues.
It's not clear why U.S. folate levels are dropping. One reason may be that food producers aren't using as much folic acid as they used to. Another reason may be the popularity of low-carb diets, in which people cut back on the foods typically fortified with folate.
The CDC is keeping a close eye on the trend. Meanwhile, it's a good idea for women of childbearing age to be sure they get at least 400 micrograms of folate (or folic acid) every day.
The CDC report appears in the September issue of The American Journal of Clinical Nutrition.