Food Fortification Plan Likely to Reduce Birth Defects Risks

The U.S. Government's plan to fortify grains with the vitamin folic acid to help prevent a devastating class of birth defects is likely to reduce the risk of these defects substantially, according to an early study by researchers in Ireland and at the National Institute of Child Health and Human Development (NICHD). Some researchers had feared that the amount of folate that will be added to grains-kept low so as not to jeopardize the health of those who may not need extra folate-is not enough to prevent the birth defects.

The study, which appeared in the December 6 issue of The Lancet, was led by Sean Daly, of Coombe Women's Hospital in Dublin (now at Thomas Jefferson Hospital in Philadelphia, PA). The research team also included members from the NICHD, from Trinity College in Dublin and from the Health Research Board of Ireland.

Briefly, the study treated a group of women of childbearing age with different doses of folic acid (0, 100, 200, or 400 micrograms) for 6 months to determine how much was needed to raise their blood folate to a level known to protect against most neural tube defects. The researchers found women receiving 100 micrograms reached a level that would prevent 22 percent of NTDs. The women receiving 200 micrograms did even better; they reached a level - that would prevent 41 percent of NTDs.

Neural tube defects (NTDs) are a class of birth defects affecting the brain or spinal cord. They occur in about one per thousand pregnancies in the U.S. each year. Among the most common NTDs are spina bifida, in which a piece of the spinal cord protrudes from the spinal column, causing paralysis below the protrusion, and anencephaly, a fatal condition in which the brain fails to develop normally.

Experts believe that around 50 percent of neural tube defects can be prevented by folic acid and that 200 micrograms a day is a highly effective dose. Previous studies have found that women who take folic acid shortly before and just after they conceive a child are less likely to give birth to a child with an NTD, according to a member of the research team, James L. Mills, MD, Chief of the NICHD's Pediatric Epidemiology Section.

In addition, the United States Public Health Service currently recommends that all women of childbearing age take a 400 microgram folic acid supplement each day; however, this recommendation is not widely followed. (Folic acid is the form found in vitamin pills; folate is the natural form found in foods.)

Because women are not getting the recommended supplements, the FDA has instituted a program to fortify food with folic acid. By January 1, 1998 , 140 micrograms of folic acid will be added to every 100 grams of grain. This dose should assure an increase of 100 micrograms in the diet of the average woman of childbearing age.

Thus, this study is important for two reasons, Dr. Mills explained. First, it demonstrates for the first time that 100 micrograms will be sufficient to prevent many NTDs. Second, it demonstrates that 200 micrograms will prevent most of the NTDs that are possible to prevent with folate.