Experts
Debate on Folic Acid: How Much Is Enough?
Folic acid fortification of foods, mandated since
1998 in the US, continues to help reduce the incidence of severe birth
defects such as spina bifida, according to a study reported in the
journal Pediatrics.
The study included a look at the effects of folic
acid, a B vitamin, on children born to African-American and Hispanic
women.
"We wanted to see if all racial and ethnic groups
are having decreases, or is it only, for example, in one group?" explains
study co-author Dr. Sonja Rasmussen, a clinical geneticist with the Centers
for Disease Control and Prevention (CDC).
The CDC team concluded
that folic acid fortification accounted for a 36 percent decline in
the birth defects among the Hispanic population, and a 34 percent decline
in the non-Hispanic Caucasian population. The decline among African-American
women was not significant.
Before fortification, about 4,000 pregnancies annually
were affected by neural tube defects, according to the March
of Dimes. Now, about 1,000 fewer babies a year develop one of
these conditions.
Dr. Rasmussen's team analyzed data from 21 population-based
birth defect surveillance systems.
They examined trends in neural tube defects - serious
malformations such as spina bifida, a leading cause of childhood paralysis,
and anencephaly, a condition in which parts of the brain and skull
cap are missing.
Both can be prevented through maternal intake of
folate during pregnancy. Folate is thought to be important to embryonic
development. Folate is a form of folic acid that occurs naturally in
foods such as leafy green vegetables, citrus fruits, and dried beans
and peas.
Looking at the years 1995 to 2002, the team divided
births into pre-fortification, optional- and mandatory-fortification
periods, and then evaluated associations between maternal folate levels
and birth defects.
The study included data on 4,468 cases of spina
bifida and 2,625 cases of anencephaly.
But some experts believe the fortification level,
while helpful, needs to be set higher.
In an editorial accompanying the study, Dr. Godfrey
Oakley, Jr. of the CDC says the US
Food and Drug Administration should at least double the amount
of folic acid required in enriched grain foods, currently set at 140
micrograms per 100 grams of grains.
The March of Dimes is
also calling for higher fortification levels, says Dr. Jennifer Howse,
president of the organization. She calls the decline found in the Dr.
Rasmussen study "very significant," but thinks higher levels of fortification
are needed.
In a note of caution, however, Dr. Tsunenobu Tamura,
author of a second Pediatrics study on
folate status and child development, said more study is needed before
that recommendation should be enacted.
"We should be extremely careful in increasing the
fortification level because we do not know the consequences of high-dose
fortification," says Dr. Tamura, a professor of nutrition science at
the University of Alabama at Birmingham.
In his study, Dr. Tamura's team evaluated the maternal
blood folate levels of African-American women at 19, 26, and 37 weeks
of pregnancy. They then evaluated the neurological development of 355
of the women's children at five years of age using memory, motor skills,
and other tests.
"The mothers' folate nutritional status during pregnancy
does not appear to affect psychomotor development of the children at
five years of age," he says.
Still, he notes, he believes it is crucial that
women get adequate folate during pregnancy.
Women of childbearing age are advised to take in
400 micrograms a day of folate, which can be obtained through vitamin
pills or foods such as leafy green vegetables and citrus fruits.
Always consult your physician for more information.
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