Pregnant? Eat More Fish to Benefit Baby's Brain
A new study suggests even higher-mercury fish like tuna can increase cognitive function
Worried about consuming too much mercury from fish while you're pregnant? Maybe you should be more worried about not eating enough fish, or so a new study suggests.
It found that women who ate the most fish while pregnant — even more than the standard recommended limits in the United States, and including large, fatty fish such as tuna — had kids who scored better on tests used to measure cognitive development compared to moms who ate the least.
The kids also showed fewer symptoms of autism-spectrum disorder by age 5.
The study, published in the American Journal of Epidemiology, was conducted by scientists at the Center for Research in Environmental Epidemiology in Barcelona. It followed nearly 2,000 Spanish moms and their babies from the women’s first trimester of pregnancy to their children’s fifth birthdays.
The findings could be especially welcome news for women who love seafood but limit how much they eat for the nine long months they’re expecting.
The U.S. Food and Drug Administration (FDA) underscores the value of eating fish during pregnancy. It notes that for years women have avoided fish or limited their fish consumption during pregnancy. “But emerging science now tells us that limiting or avoiding fish during pregnancy and early childhood can mean missing out on important nutrients that can have a positive impact on growth and development as well as on general health.”
The most recent guidelines advise pregnant women to "eat at least 8 ounces and up to 12 ounces (2-3 servings) per week of a variety of fish that are lower in mercury."
The limits are based largely on concerns that certain kinds of fish contain high levels of pollutants such as polychlorinatedbiphenyls (PCB) and mercury. Mercury is a neurotoxin that's been found to cause developmental problems in children. In the study, however, even when women ate nearly twice the recommended amount of fish per week — around 21 ounces — no signs of a negative effect from these pollutants were observed in their children by age 5.
Should you take the bait?
If you’re pregnant or planning to become pregnant, these findings don't mean you should eat as much fish as you want and whatever kind you like. The study was observational, which means it wasn't designed to prove cause and effect. Observational studies simply show associations. More research is needed. Your obstetrician or other health care provider can help you make sure your diet is safe and beneficial for your baby.
The warning to steer clear of fish known to be highest in mercury still stands. These include long-lived species such as catfish, shark, swordfish and giant mackerel. There are plenty of safe options for fatty fish, including sardines, anchovies and salmon, and for lean fish, including as hake or sole, not to mention shellfish and other seafood.
Related: How to Choose Safe, Sustainable Fish