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 Since 1998, the U.S. has required companies to add folic acid to
cereal grains to prevent birth defects in the brain and spine. But
the new study found that a decrease in these defects actually slowed
after the regulation took effect.
By 1998, doctors had already been advising women for years to take
folic acid supplements, which might explain the findings, said Dr.
Irina Burd, an associate professor of gynecology and obstetrics and
neurology at Johns Hopkins Medicine in Baltimore who was not
involved in the study.
"We shouldn't be changing our behaviors or recommendations at all
based on this study," said lead researcher Gary Shaw, of Stanford
University in California.
"We don’t want any message to get out there that folic acid is a bad
thing," Shaw told Reuters Health. Instead, he said, "we need to know
more."
The 1998 mandate from the U.S. Food and Drug Administration calling
for folic acid fortification of grains has been tied to a 36 percent
reduction in neural tube defects, according to the Centers for
Disease Control and Prevention.
But some have questioned whether fortification of grains was
responsible for that change, or if it was partly due to an already
falling rate of birth defects.
For the new study, the researchers looked at data from all live
births and stillbirths in central California between 1989 and 2010.
Before fortification in 1998, neural tube defects had been falling
by a rate of about nine cases per 100,000 births per year and that
slowed to about two cases per 100,000 births per year after
fortification.
Other types of congenital defects began to decline, however.
The rate of gastroschisis, for example, had been rising by about
four cases per 100,000 births per year but slowed to about one case
per 100,000 births per year after fortification.
The researchers also found that cleft lips and cleft palates were
increasing before fortification but started to decrease after
fortification, according to a paper released May 18 by the journal
Birth Defects Research Part A.
The study did not account for the fact that women of childbearing
age were already being told to supplement with folic acid since the
early 1990s, Burd told Reuters Health.
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"I think it’s a great study when you look at 1999 to 2009 and you
say fortification is working, but it’s harder to compare it to the
earlier (years)," said Burd, who was not involved in the new study.
"It’s missing this history behind it," she said.
Shaw noted that other factors might have influenced the results.
Rising obesity could explain a slower decrease in rates of spine and
brain defects and a slower increase in gastroschisis, for example.
Additionally, the researchers didn't have data on birth defects
among terminated pregnancies, which could skew the results.
Shaw said more research is needed to know how folic acid
fortification affects rates of birth defects.
"These kinds of studies, they don’t nail down the specifics," he
said. "They nail down the grand overarching view of something as a
signal to look here. It’s not saying anything is good or bad here."
Women should still follow the U.S. recommendations for folic acid,
he said.
Currently, the U.S. Preventive Services Task Force advises women who
are pregnant or capable of becoming pregnant to take a daily
supplement containing 400 to 800 micrograms of folic acid.
SOURCE: http://bit.ly/1qtxSWW
Birth Defects Research Part A: Clinical and Molecular Teratology
2016.
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