Researchers followed nearly 2,000 mother-child pairs from the first
trimester of pregnancy through the child’s fifth birthday and found
improved brain function in the kids whose mothers ate the most fish
while pregnant, compared to children of mothers who ate the least.
Even when women averaged 600 grams, or 21 ounces, of fish weekly
during pregnancy, there was no sign that mercury or other pollutants
associated with fish were having a negative effect that offset the
“Seafood is known to be an important source of essential nutrients
for brain development, but at the same time accumulates mercury from
the environment, which is known to be neurotoxic,” lead author Jordi
Julvez, of the Center for Research in Environmental Epidemiology in
Barcelona, said in an email.
In an attempt to balance the potential harms of such pollutants with
the general health benefits of fish, the U.S. Food and Drug
Administration’s 2014 guidelines encourage pregnant women to eat
fish, but no more than 12 ounces per week.
The European Food Safety Authority recently issued a scientific
opinion endorsing 150 g to 600 g of fish weekly during pregnancy,
Julvez and colleagues note in the American Journal of Epidemiology.
But, the study team writes, the effects of maternal fish consumption
during development are still not well understood and more research
could help give pregnant women clearer guidance.
The researchers analyzed data from the Spanish Childhood and
Environment Project, a large population study that recruited women
in their first trimester of pregnancy, in four provinces of Spain,
between 2004 and 2008.
Julvez and colleagues focused on records of the women’s consumption
of large fatty fish such as swordfish and albacore tuna, smaller
fatty fish such as mackerel, sardines, anchovies or salmon, and lean
fish such as hake or sole, as well as shellfish and other seafood.
Women were tested for blood levels of vitamin D and iodine, and cord
blood was tested after delivery to measure fetal exposure to mercury
and PCB pollutants. At ages 14 months and five years, the children
underwent tests of their cognitive abilities and Asperger Syndrome
traits to assess their neuropsychological development.
On average, the women had consumed about 500 g, or three servings,
of seafood per week while pregnant. But with every additional 10 g
per week above that amount, children’s test scores improved, up to
about 600 g. The link between higher maternal consumption and better
brain development in children was especially apparent when kids were
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The researchers also saw a consistent reduction in autism-spectrum
traits with increased maternal fish consumption.
Mothers’ consumption of lean fish and large fatty fish appeared most
strongly tied to children’s scores, and fish intake during the first
trimester, compared to later in pregnancy, also had the strongest
“I think that in general people should follow the current
recommendations,” Julvez said. “Nevertheless this study pointed out
that maybe some of them, particularly the American ones, should be
Julvez noted that there didn’t appear to be any additional benefit
when women ate more than 21 oz (about 595 g) of fish per week.
“I think it's really interesting, and it shed a lot more light on
the benefits of eating fish during pregnancy,” said Dr. Ashley
Roman, director of Maternal Fetal Medicine at NYU Langone Medical
Center in New York.
“I think what's interesting about this study compared to some data
previously is that they better quantify the relationship between how
much fish is consumed in a diet and then the benefits for the fetus
and ultimately the child,” said Roman, who was not involved in the
“They're able to correlate the fish consumption with protection from
autism and I think that is potentially a very important finding,”
Roman said that fish is really important for the fetus's brain
“We still recommend that women avoid the fish that are highest in
mercury like catfish, shark, swordfish and giant mackerel, typically
the larger fish that have longer lifespans and they tend to
concentrate more mercury in their tissue,” she said.
SOURCE: http://bit.ly/1RnLwGO American Journal of Epidemiology,
online January 5, 2016.
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