Folic Acid Curbs Birth Defects, Scientists Report
Fortifying flour, rice, cornmeal, pasta and other enriched grain products with folic acid appears to be doing what it was designed to do: help prevent a class of devastating birth defects, including spina bifida.
Since 1998, when a new law dictated that enriched grain products include folic acid, nationwide rates of neural tube defects have decreased nearly 20%, scientists report.
In the United States, the federal Centers for Disease Control and Prevention estimates that 1 in 1,000 babies--2,500 a year--are born with a neural tube defect.
Health professionals are cheered by the apparent decrease in cases, reported today in the Journal of the American Medical Assn. But they also stressed the need to do better.
Some argue that the level of folic acid fortification should be higher. On average, the fortification provides a person with about 100 micrograms of folic acid daily. All agree that women of child-bearing age should not rely solely on the folic acid found in fortified grains and naturally in such foods as green leafy vegetables, beans and citrus fruits. Women should also take a folic acid supplement, experts say.
“We want women to stay aware that they need 400 micrograms of folic acid daily,” said Margaret A. Honein, lead author of the study and an epidemiologist with the CDC’s National Center on Birth Defects and Developmental Disabilities.
Until now, “we really didn’t have much information about whether folic acid fortification was doing what it was designed to do--prevent neural tube defects. This study really provides this information,” said Dr. James Mills, chief of the pediatric epidemiology section at the National Institute of Child Health and Human Development.
However, Mills and others agree that the study has limitations. It relies on often incomplete information about neural tube defects recorded on birth certificates and does not account for miscarriages or abortions.
Inadequate intake of folic acid can lead to defects in which the spinal column of a fetus does not properly close during the first month of pregnancy.
The result can be spina bifida--which causes paralysis or a rarer condition called anencephaly, in which the brain is not properly formed and the baby dies.
Studies suggest that supplementation could prevent 50% to 75% of neural tube defects. Adequate folic acid is vital very early in pregnancy. Natural sources of folic acid are not as easily absorbed by the body as supplements. Yet despite educational campaigns, surveys suggest that only one-third of women take the recommended 400 micrograms a day.
The U.S. Food and Drug Administration has required since 1998 that enriched grain products contain folic acid in addition to other B vitamins and iron.
In the study released today, Honein and colleagues examined birth certificate data from 45 states. They compared rates of spina bifida and anencephaly from October 1995 to December 1996 (before fortification) and October 1998 through December 1999 (after fortification.)
The scientists found that rates of spina bifida declined 23% and rates of anencephaly declined 11%--together, a 19% decline in neural tube defects.
Honein says it is possible that something other than fortification is behind the decline--such as increased screening for neural tube defects, followed by more terminations of pregnancies. However, she said, termination rates have held fairly steady in the period examined.
“It’s a great example of how research gets translated into policy--and the policy works,” said Dr. John Harris, director of the California Birth Defects Monitoring Program in Oakland.
Many health professionals are asking if a 19% reduction is all that can be achieved, because research suggests the number should be closer to 50 % to 75%. Should foods be fortified at a higher level?
“The issue is: Great, we got the decline we expected,” said Dr. Ed McCabe, executive chairman in the department of pediatrics and physician-in-chief of the Mattel Children’s Hospital at UCLA. “Why not go for more?”
The appropriate level of fortification has been hotly debated, said Dr. Jennifer Howse, president of the March of Dimes Birth Defects Foundation. The foundation--as well as several other groups--had lobbied for a higher level.
“These are serious and devastating birth defects, and so the March of Dimes quite firmly believes that the fortification levels ought to be higher,” Howse said.
But other health professionals, including Mills, argue that adding more folic acid to the food supply would be imprudent without more research. Large amounts of folic acid can make it harder to detect vitamin B-12 deficiencies that crop up in elderly people. If left untreated, such deficiencies can cause serious nerve damage.
More research, scientists agree, is needed to sort out all these issues.
Folic acid may also help prevent heart disease--by lowering blood levels of an amino acid called homocysteine--as well as colon cancer, mental decline and depression.
