The U.S. government decision to add folic acid to enriched grain products has reduced the incidence of two devastating birth defects but more needs to be done, according to reports published on Tuesday.

A review of births in 21 states from 1995, a year before the fortification was authorized, to 2002 found “significant decreases in the prevalence of spina bifida and anencephaly,” two neural tube defects that result, respectively, in spine and brain damage, one study said.

But the researchers found a racial disparity, with children born to black women less likely to be protected, perhaps because of genetic differences or gaps in education, the study from the U.S. Centers for Disease Control and Prevention and the University of Alabama said.

“Educational efforts regarding the importance of consumption of folic acid-containing supplements and food high in folic acid and natural folate among women of all racial/ethnic groups should be continued,” the study recommended.

Folic acid is a B vitamin found in such foods as leafy green vegetables, beans and orange juice. Enriched grain products include breads and pasta. Women for some years have been advised to eat such foods and also take supplements during pregnancy to avoid neural tube defects.

The study was published in the September issue of Pediatrics, the journal of the American Academy of Pediatrics, along with a commentary from two physicians who said the current level of folic acid in enriched grain products is still too low.

There are 2,000 children born every year in the United States with defects that could be prevented if the fortification levels were higher, they said, in addition to 200,000 such children born around the world yearly who could have escaped the problems if grain products generally were more enriched.

Robert Brent of the A.I. duPont Hospital for Children in Wilmington, Delaware, and Godfrey Oakley of Emory University in Atlanta, said the current fortification level should be doubled. It is currently set at 140 micrograms of folic acid per 100 grams of grain.

The March of Dimes Birth Defects Foundation concurred that a higher level is warranted, issuing a statement saying studies have shown that adequate daily folic acid intake beginning before pregnancy can reduce the incidence of such defects by up to 70 percent, “and we should not settle for anything less than maximum prevention.”