Folic Acid: 400 Micrograms of Prevention

It's been eight years since federal health officials announced that folic acid was so effective at preventing a certain type of birth defect that all women of childbearing age should take it.

In 1998, the government even mandated that cereal and grain products be fortified with folic acid--a form of vitamin B--to prevent neural tube defects, which involve the spinal cord. Now, however, public health leaders are facing the unsettling realization that none of their efforts have worked to prevent this serious type of birth defect.

The failure of women and their doctors to embrace the folic acid message has perplexed health officials, who say that as many as 2,000 to 2,800 cases of neural tube defects (out of the estimated 4,000 a year) could be avoided in the United States if all women of reproductive age consumed enough folic acid.

"Five years ago, we thought that if we just told people about it, they would naturally take it. We thought that would be enough," says Judith S. Gooding, director of the March of Dimes' folic acid campaign.

Women and their doctors may not realize that folic acid is only effective if taken in the first few weeks of pregnancy, before a woman even knows she's pregnant, Gooding says. For this reason, it's important for all women of reproductive age to consume 0.4 milligrams (or 400 micrograms) of the vitamin routinely in case they become pregnant. About half of all pregnancies are unplanned.

The Problem Is Getting Folic Acid Into Women

Getting enough folic acid through diet is extremely difficult, requiring women to eat several cups of foods high in folic acid each day. But getting women to take a vitamin every day--often for years and even if pregnancy is not on a woman's radar screen--has also proved to be an enormous challenge.

"The fact that we know how to prevent this defect hasn't had an effect," says Charlotte Dickinson, a researcher and expert on birth defects for the Centers for Disease Control and Prevention in Atlanta. "The real problem is getting people aware of what is going on."

Neural tube defects occur 18 to 28 days after conception. During this period, the small collection of fetal cells, which begins to grow as a flat patch, folds over and curves, with the edges forming what will be the spinal cord.

If the top of the spinal cord fails to close, a baby is born without a brain, a condition called anencephaly. This results in stillbirth or death within a day or so.

If the lower part of the neural tube doesn't close completely, the damage to the spinal cord causes spina bifida. Spina bifida can range from mild, such as difficulty walking, to severe, such as the inability to move limbs and mental retardation.

The actual cause of neural tube defects is not well understood. Since the defect occurs repeatedly in some families and is more prevalent among certain ethnic groups, such as Latinos, researchers believe genes may play a role.

"We don't know the causes of spina bifida or the mechanisms by which folic acid prevents spina bifida," says Dickinson. "We do know it works."

Experts are also recommending that women who have already had a baby with a neural tube defect or terminated a pregnancy due to the presence of the defect should consume 10 times the recommended amount--4 milligrams--to prevent a recurrence.

The evidence for folic acid's preventive effect is overwhelming. Besides scores of studies that led to the 1992 federal recommendation, a Chinese study scheduled to be published later this year in the New England Journal of Medicine will make a strong case for folic acid's use.

That study found that women in China who took 400 micrograms of folic acid regularly had an 85% reduction in neural tube defects compared with women who took no vitamin supplement. The Chinese women were told about the study when they registered to marry and stayed on the vitamin until after the birth of their first child.

"An 85% reduction for a public health intervention is quite amazing," Dickinson notes.

Other preliminary research suggests that folic acid also helps prevent low birth weight, prematurity, cleft palate and congenital heart defects in babies. And, last month, researchers at the Food and Drug Administration in Bethesda, Md., found that women with a gene that prevents them from metabolizing folic acid efficiently were much more likely to have a child with Down syndrome.
"This was a small study and probably affects only a small number of babies with Down syndrome. But it's part of the growing body of evidence about the importance of folic acid," Dickinson says.

And there is evidence that folic acid may also help mothers prevent coronary heart disease and colon and cervical cancer.

So, if the evidence is so strong and the defect is so horrendous, why aren't more women embracing the folic acid message?

Lack of Awareness and Communication Blamed

Experts suggest the problem is a lack of awareness about taking the supplement for the entire course of a woman's reproductive years (roughly ages 13 through 45); physicians' unwillingness to take the time to counsel their patients; and the difficulty in getting enough folic acid from diet alone.

There are three ways to get folic acid: through one's regular diet, by eating fortified foods--cereal, pasta and others--or by taking folic acid supplements or a multivitamin containing folic acid. The vitamin is found naturally in leafy vegetables, fruit, legumes and liver. But most food products contain only small amounts of the vitamin.

"There are no randomized trials to show you can [get enough of the vitamin] by diet alone," she says.

There were high hopes that fortification of food would ensure that women could get enough of the vitamin through diet. But the government required such a low rate of fortification (each serving of an enriched grain must contain 10% of the recommended daily amount of folic acid) that it's still hard to consume enough, says Gooding.

The fortification rate was kept low, she says, because of a fear that too much folate--about 1,000 micrograms per day--can cause a condition called pernicious anemia, a dangerous blood disease, or can mask a vitamin B-12 deficiency.

Because only 3% of women will get enough folic acid by eating fortified foods alone, experts are continuing to push the FDA to allow food manufacturers to include higher levels of the vitamin in their products, says Gooding, who, with Dickinson, spoke to representatives of the dietary supplement industry earlier this month at the annual meeting of the Council for Responsible Nutrition in Rancho Mirage.

Encouraging women to take a supplement is unique because it appears to be the first time that major public health groups have endorsed routine use of a dietary supplement. While calcium supplements are promoted to prevent osteoporosis, for example, most public health groups encourage women to try to get the calcium from food first and take a supplement only if needed.

"This is different in that there is a recognition of the need for supplements," says Annette Dickinson, of CRN, a trade group for the dietary supplement industry.

The hardest group to reach may be the doctors who care for women, experts say. A 1998 survey by the March of Dimes found that only 30% of doctors knew about the 1992 FDA recommendation. And only 53% knew that a woman is unlikely to get enough folic acid through diet alone. Less than one-third said they recommend folic acid to their patients of childbearing age.
"They need to be doing more than they're doing, and we need to help them," Gooding says. "There are health care providers who have known about folic acid since 1992 and are not telling women." .