This B vitamin has long been known to play an important role in nerve-tissue development, and folate requirements increase during pregnancy because of rapid tissue growth. 3 British researchers first suggested the use of multivitamins containing folic acid to reduce the risk of NTD in 1965. Since 1988, eight major epidemiological studies have investigated the protective effect of folic acid alone or in a multivitamin supplement, and seven of the studies have shown positive results. For example, an Atlanta study found a 60 percent reduction in NTD risk among women who had taken multivitamin supplements including folic acid for three months before and after conception. A Massachusetts study found a 70 percent reduction in NTD risk when women took a multivitamin supplement containing folic acid before and during the first six weeks of pregnancy.
Clinical studies tell a similar story.
In a 1991 study of women in seven countries, the Medical Research Council of Great Britain found that NTD risk fell by 70 percent in women who had had a previous NTD pregnancy and took a 4-mg daily folic acid supplement. Now, the U.S. Public Health Service recommends that all women of child-bearing age consume at least 400 micrograms of folic acid daily. This recommendation applies to any woman who might become pregnant simply because the benefits occur so early in pregnancy. Yet, getting 400 micrograms of folic acid daily from diet alone is often difficult, even though folates are found in a wide variety of foods. 3 Recent promotions for orange juice have even emphasized the product's benefits to pregnant women because of its folic acid content.