Folic
acid is a B vitamin that can help prevent birth defects of the brain and
spinal cord called neural tube defects (NTDs).
Folic acid works to prevent these birth defects only if taken before
pregnancy and in the first few weeks of pregnancy. Since NTDs originate
in the first month of pregnancy, before many women know they are pregnant,
it is important for a woman to have enough folic acid in her system before
conception.
Folic acid is recommended for all women of childbearing age because 50
percent of pregnancies in this country are unplanned.
Here's
what women should know:
Studies show that, if all women consumed the recommended amount of this
vitamin, beginning before conception and continuing into the first month
of pregnancy, up to 70 percent of all NTDs could be prevented. The neural
tube is the embryonic structure that develops into the brain and spinal
cord. This structure, which starts out as a tiny ribbon of tissue, normally
folds inward to form a tube by the 28th day after conception. When this
process goes awry and the neural tube does not close completely, defects
in the brain and spinal cord can result.
About 2,500 babies are born with NTDs each year, and many other affected
pregnancies end in miscarriage or stillbirth.
The most common NTDs are spina bifida and anencephaly. Spina
bifida, often called open spine, affects the backbone and, sometimes,
the spinal cord. Children with the severe form of spina bifida have
some degree of leg paralysis and bladder and bowel control problems.
Anencephaly is a fatal condition in which a baby is born with a severely
underdeveloped brain and skull.
Studies also suggest that folic acid may help prevent some other birth
defects as well, including cleft lip and palate.
How much folic acid does a woman need?
The March of Dimes recommends that all women who can become pregnant
take a multivitamin that contains 400 micrograms of folic acid every
day and eat a healthy diet. This is the only sure way a woman can
get all the folic acid and other vitamins she needs. Most women get less
than half of the recommended amount of folic acid daily. The Institute
of Medicine also recommends that women eat a diet rich in foods that contain
folate or folic acid. Folate is the natural form of folic acid that is
found in foods.
Orange juice, other citrus fruits and juices, leafy green vegetables,
beans, peanuts, broccoli, asparagus, peas, lentils and whole grain products
all contain folate.
Synthetic (manufactured) folic acid is added to certain grain products,
including flour, rice, pasta, cornmeal, bread and cereals. These foods
are considered "fortified" with folic acid.
The body more readily absorbs folic acid from vitamin supplements and
fortified foods than folate from food. It is estimated that 50 percent
of food folate is absorbed by the body, while approximately 85 percent
of folic acid in fortified foods and 100 percent of the folic acid in
a vitamin supplement are absorbed.
Cooking and storage also destroy some of the folate in foods. The
body cannot distinguish the origin of the vitamin, however; once in
the bloodstream the biological function is the same.
Numerous studies have shown that the synthetic form of folic acid helps
prevent NTDs. This is why the March of Dimes, the Centers for Disease
Control and Prevention (CDC), and the Institute of Medicine recommend
that women who could become pregnant consume 400 micrograms a day of the
synthetic form. This is the amount contained in most multivitamins.
A few breakfast cereals contain this amount in one bowl, but most contain
only 25 percent of the recommended amount, so it is important to check
the label on the box.
Do some women need more folic acid?
The Institute of Medicine recommends that women increase their
intake of synthetic folic acid to 600 micrograms a day once their pregnancy
is confirmed.
Most doctors recommend a prenatal vitamin that contains at least
this amount of folic acid.
However, women should not take more than 1,000 micrograms
(or 1 milligram) without their doctor's advice.
If a woman already has had a baby with an NTD, she should consult
her doctor before her next pregnancy about the amount of folic acid she
should take.
Studies have shown that taking a larger dose of folic acid daily (4
milligrams), beginning at least one month before pregnancy and in the
first trimester of pregnancy, reduced by about 70 percent the risk of
having another affected pregnancy.
Women with diabetes or epilepsy also are at increased risk of
having a baby with an NTD. Women with these disorders should consult their
doctors prior to pregnancy to see whether they should take a larger dose
of folic acid.
How much folic acid is in fortified foods?
Since January 1, 1998, the U.S. Food and Drug Administration (FDA)
has required the addition of 140 micrograms of folic acid per 100 grams
of grain to cereals, breads, pastas and other foods labeled "enriched."
This makes it a little easier for women to obtain folic acid from their
diets. However, the amount added to these foods is small, and most women
cannot obtain enough folic acid from their diet alone. It is estimated
that the addition of 140 micrograms of folic acid to foods will prevent
only about 5 to 20 percent of folic acid-preventable NTDs. The
FDA did not require that more than this amount of folic acid be added
to these foods because of the concern that high levels of folic acid
might mask a vitamin B-12 deficiency. This potentially dangerous condition
is called pernicious anemia and is seen mainly in elderly people.
Very high doses of folic acid (over 1,000 micrograms a day) could possibly
correct the anemia caused by the vitamin deficiency, but not the deficiency
itself, and cause its diagnosis to be delayed. Left untreated, the vitamin
B-12 deficiency can cause irreversible neurologic damage. Some health
organizations, including the March of Dimes, feel that the level of
fortification can be safely increased without risk to the public's health.
Research currently is under way to examine the possibility.
How does folic acid prevent birth defects?
How folic acid prevents NTDs is not well understood. Most studies suggest
that it may correct a nutritional deficiency, while others suggest
that supplemental folic acid helps some people compensate for inborn
errors in how the body processes folates. For example, a 1997 study
found that as many as one in seven people may carry a genetic mutation
(change) that causes them to have a deficiency in folic acid, even if
they are consuming a diet that contains the recommended amount of folates.
These people have problems breaking down folates found in food to forms
of folic acid the body can use, resulting in lower folic acid levels
in the blood. Most mothers of babies with NTDs don't have this gene
mutation, but studies suggest that women who do may be at increased
risk of having a baby with an NTD.
However, taking folic acid raises levels of the vitamin in the blood,
which can reduce the risk of having an affected baby. A new study also
suggests that women with this mutation may have an increased risk of
placental problems, such as placental abruption (when the placenta
peels away from the wall of the uterus before delivery). This risk
may be reduced by taking folic acid throughout pregnancy.
Besides helping to prevent certain birth defects, folic acid plays other
important roles during pregnancy. A pregnant woman needs extra folic
acid to help her to produce the additional blood cells she needs.
Folic acid also is crucial to support the rapid growth of the placenta
and fetus. This vitamin is needed to produce new DNA (genetic material)
as cells multiply. Without adequate amounts of folic acid, cell division
could be impaired, possibly leading to poor growth in the fetus or placenta.
One study found that women who were deficient in folic acid were more
likely to have a baby who was premature and of low birthweight
(less than 5-1/2 pounds). Another recent study found that low levels
of folate may be a risk factor for repeated early miscarriages.
Does folic acid have other health benefits?
In recent years, doctors have come to realize that folic acid is very
important for everyone in maintaining health. It has long been known that
folic acid plays an important role in the production of normal red blood
cells, and that individuals who were deficient in folic acid sometimes
developed a form of anemia called megaloblastic anemia (characterized
by a reduced number of red blood cells).
More recent studies suggest that folic acid also may help prevent
heart disease and stroke. It appears that individuals who have a high
level of a substance called homocysteine in their blood have an increased
risk of heart disease and stroke. When these people take folic acid, the
level of homocysteine in their blood drops, possibly decreasing their
risk of cardiovascular diseases. (Researchers also are looking at the
role of high homocysteine levels in causing birth defects.) Other studies
suggest that folic acid also may help prevent certain cancers, especially
colon cancer. While these studies have not proven a protective effect,
they suggest that many people, besides women of childbearing age, may
benefit from taking folic acid.
Folic
acid is a B vitamin that can help prevent birth defects of the brain and
spinal cord called neural tube defects (NTDs). 
Here's
what women should know:Studies show that, if all women consumed the recommended amount of this vitamin, beginning before conception and continuing into the first month of pregnancy, up to 70 percent of all NTDs could be prevented. The neural tube is the embryonic structure that develops into the brain and spinal cord. This structure, which starts out as a tiny ribbon of tissue, normally folds inward to form a tube by the 28th day after conception. When this process goes awry and the neural tube does not close completely, defects in the brain and spinal cord can result.
Orange juice, other citrus fruits and juices, leafy green vegetables, beans, peanuts, broccoli, asparagus, peas, lentils and whole grain products all contain folate.
