U.S. Advises Folic Acid Use to Reduce Birth Defects : Health: Women of child-bearing age told to take the B vitamin to prevent neural tube disorders in infants.
All women of child-bearing age should take folic acid, a B vitamin, to reduce the chances of having a baby with neural tube defects, particularly spina bifida and anencephaly, federal health officials recommended Monday.
The announcement is believed to be the first time the federal government has recommended the widespread use of vitamins other than during pregnancy.
All female adolescents and women who could become pregnant should consume 0.4 milligrams (sometimes also listed as 400 micrograms) of folic acid daily, but should be careful to restrict their intake to less than 1 milligram because an overdose could cause health problems, said the federal Centers for Disease Control, which initiated the proposal.
About 2,500 infants are born annually with the neural tube defects in the United States, and health officials estimated that as many as half the cases could be prevented by taking the vitamin. Spina bifida is a condition in which the spinal cord is exposed. In anencephaly, most or all of the brain is missing.
“This . . . will save lives of some children who might otherwise have died . . .,” said CDC Director Dr. William L. Roper in a speech Monday in Atlanta. “It will also reduce the lifelong disability which other children who survive with spina bifida now experience.”
But the Food and Drug Administration, which traditionally has been reluctant to promote the use of vitamins, said it was not yet prepared to allow food manufacturers to make health claims about products containing folic acid. Neither is the agency ready to allow more foods to be fortified routinely with the vitamin, FDA officials said.
“When a drug is approved, we have some control over who gets it, but once a food is out there, we have no control over who is exposed to it,” said FDA Commissioner David A. Kessler in a speech Monday at Tufts University in Boston. “The line between benefit and risk with folic acid is apparently quite narrow. . . . The dose at which we see positive effects in reducing the risk of neural tube defects is uncomfortably close to the doses at which we begin to have safety concerns.”
The major worry is that too much folic acid can mask the symptoms of Vitamin B12 deficiencies, among them, pernicious anemia, a rare disease that is potentially fatal.
The FDA said it intends to convene a scientific panel to discuss the issue.
Good sources of folic acid in the diet include leafy, dark green vegetables, citrus fruits and juices, yeast, bread and beans and fortified breakfast cereals. Folic acid supplements and daily multivitamin preparations containing 0.4 milligrams of folic acid also are widely available.
There is little risk that a woman who takes a folic acid supplement and receives it through a normal diet will inadvertently receive too much folic acid--unless she takes more than 0.4 milligrams in supplements, health officials said.
The average woman gets about 0.2 or 0.3 milligrams in a regular diet, “so if you add a supplement to that with 0.4 milligram, you’re still way under the concern level,” said William Grigg, a spokesman for the Public Health Service.
The recommendation applies to all women--not just those trying to become pregnant--because “50% of pregnancies are unplanned,” said Dr. Godfrey Oakley, director of the division of birth defects and developmental disabilities in CDC’s center for environmental health.
The recommendation emphasizes that consumption of folic acid begin before pregnancy because an embryo can develop spina bifida within a month of conception, often a time when women are still unaware they are pregnant.
These birth defects often can be detected during pregnancy through ultrasound and other tests. Spina bifida can be found by looking for the presence of alpha feto-protein in the mother’s blood early in pregnancy, or later, through amniocentesis, by examining the amniotic fluid surrounding the fetus. Alpha feto-protein is a common protein in the fetus’s blood that leaks into the mother’s blood and into the amniotic fluid when the tube surrounding the spinal cord is open.
The recommendation is based on an analysis of a series of studies conducted in the United Kingdom, Hungary, Cuba, Western Australia, and three in the United States, in Atlanta, California and Illinois, and another in New England.
Doses used in the studies ranged from moderate (0.4 milligrams to 0.8 milligrams) to very high (4 milligrams). Almost all of the studies showed a protective effect, and in many cases the reduction in risk was substantial.
“The data are extraordinarily strong and they have been carefully reviewed,” the CDC’s Oakley said in an interview.
In the summer of 1991, the CDC recommended that women who already have had an infant with a neural tube defect take 0.4 milligrams of folic acid during pregnancy because they were at extremely high risk of having another child with the affliction.
The latest recommendation suggests that such women now take 0.4 milligrams daily until they are planning to become pregnant, and then ask their physicians about switching to the higher doses during their pregnancies.
Folic acid is an essential nutrient used by the body to manufacture DNA, the building block required for human cell growth and organ and tissue development.
“Nobody knows yet why it works,” Oakley said. “But we know embryo cells divide faster than the mother’s, and every time cells divide, you need DNA. At the embryo level, there may not be enough folic acid to make them go at the right speed. That is a biologically plausible explanation.
“But, there are many things we know how to prevent and we don’t know what the exact mechanism is,” he added.
