According to Spanish researchers from the Center for Research in Environmental Epidemiology in Barcelona, when mothers eat three servings of fish each week during pregnancy it may benefit children’s brains for years to come.
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.
No evidence of harm from mercury, PCBs
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 apparent benefits.
In an attempt to balance the potential harms of such pollutants with the 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. 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.
The researchers 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.
More benefit with higher fish consumption
On average, the women had consumed about 500 g (18 ounces), 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 five.
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 associations.
The researchers did not find there any additional benefit when women ate more than 21 ounces (about 595 g) of fish per week.
That the researchers were able to correlate the fish consumption with protection from autism is potentially a very important finding, an expert noted. Fish is very important for the fetus's brain development.
Experts 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.
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