ATLANTA (AP) â€” American women of childbearing age more than doubled the amount of folic acid in their blood since the government in 1998 required that flour and other grains be fortified with the vitamin to help reduce birth defects, health officials said Thursday.
Officials at the Centers for Disease Control and Prevention expect the payoff will be fewer spinal and brain defects.
``We're talking about a simple intervention here that can prevent up to half of those birth defects,'' said Dr. David Fleming, CDC deputy director for science and public health. ``We're very confident.''
Since 1998, food manufacturers have been required to fortify pasta, cereals, rice and other grain products with folic acid, a B vitamin that has been shown in previous studies to reduce spinal and brain defects.
The 1999 CDC study released Thursday showed that women ages 15 to 44 averaged more than double the amount of folic acid in their blood compared with women in a similar study conducted between 1988 and 1994.
Researchers found blood levels of folic acid increased on average from 6.3 to 16.2 nanograms per milliliter. A nanogram is one billionth of a gram.
While that test measures short-term folate levels in the blood, the CDC also found increases in the amount of folic acid stored in red blood cells, where the vitamin takes longer to accumulate.
The average folate level in red blood cells was 315 nanograms per milliliter â€” exceeding the CDC's goal of a 220 average by the year 2010.
Previous studies have shown increased consumption of folic acid reduces by half the chances of a baby being born with spina bifida and other fatal defects. Fleming said those disorders affect as many as 4,000 newborns per year.
Folic acid is found naturally in citrus fruit, beans, tuna, eggs and leafy green vegetables like spinach. Before pastas and other cereals were fortified, doctors urged pregnant women to take vitamin supplements as well.
The problem, researchers say, is that folates are most beneficial very early in pregnancy â€” before many women know they are pregnant.
The CDC has not released any data showing an actual decline in birth defects since the 1998 food mandate. But studies earlier this year in South Carolina and Texas showed reductions when pregnant women increased their folic acid intake.
``It might be a year or two or three before we're able to come forward and say here's the final proof,'' Fleming said.
Dr. Donald Mattoon, medical director for the March of Dimes, called the CDC study an important step that ``does suggest that food fortification may have had an impact.''
But he cautioned that the CDC's research does not look at whether folate levels vary among different ethnic and socio-economic groups.
And the two studies the CDC used to compare folate levels used vastly different sample sizes. The 1999 survey tested blood from 650 women, compared with more than 5,000 tested between 1988 and 1994.