February 18, 2007
Higher Fish Diet Seems To Make Babies Smarter

As part of the University of Bristol Children Of The 90s project dietary information and child cognitive performance was checked for children in thousands of families (the news reports speak of 9000 families or 11,875 pregnant women - maybe the higher number includes multiple pregnancies from some of the women?) . Children whose mothers ate fish more than 3 times a week did better in tests of cognitive function.

Mothers who ate more seafood than the US guidelines (340 grams, or three portions a week) had children who were more advanced in development tests measuring fine motor, communication and social skills as toddlers, had more positive social behaviours and were less likely to have low verbal IQ scores at the age of eight. Those children whose mothers had eaten no fish were 28 per cent more likely to have poor communication skills at 18 months, 35 per cent more likely to have poor fine motor coordination at age three and a half, 44 per cent more likely to have poor social behaviour at age seven and 48 per cent more likely to have a relatively low verbal IQ at age eight, when compared with children of women who ate more than the US guidelines advised.

But did they test parental IQ? Or did they control for socio-economic status of the parents? (which would be a rough proxy for genetic differences)

Main study author Joseph Hibbeln thinks these results suggest US government advice on fish eating in pregnancy is wrong.

The new findings suggest that, for developing brains, the risks of limiting seafood consumption outweigh the benefits of such a limit, the NIH's Joseph R. Hibbeln, MD, tells WebMD.

"Regrettably, these data indicate that the [FDA-EPA] advisory apparently causes the harm that it was intended to prevent, especially with regard to verbal development," Hibbeln says.

The FDA-EPA advisory is aimed at reducing mercury exposure. But you can avoid the mercury while still getting lots of omega 3 fatty acids by either eating low mercury fish or by taking fish oil capsules.

Avoid higher mercury fish from the top of the food chain.

The study supports the contrary advice, given by the Food Standards Agency in the UK, which backs fish as a healthy food. The FSA simply advises mothers to avoid shark, swordfish and marlin, and restrict their intake of tuna.

The new research into children’s behaviour and intelligence suggests that women who follow the US “advisory” issued in 2004 to limit consumption, or cut fish out of their diet altogether, may miss nutrients that the developing brain needs — and so harm their children.

The women filled out a seafood consumption questionnaire while pregnant.

At 32 weeks into their pregnancy, the women were asked to fill in a seafood consumption questionnaire. They were subsequently sent questionnaires four times during their pregnancy, and then up to eight years after the birth of their child. Researchers examined issues including the children's social and communication skills, their hand-eye coordination, and their IQ levels. As with any study based on self-reporting methods, however, the results cannot be considered entirely definitive.

What I want to know: Did the mothers who ate less fish have lower IQs than the mothers who ate more fish? In other words, did these researchers measure an effect of nutritional differences or of genetic differences?

We still do not know with certainty that omega 3 fatty acids help make babies smarter. But since there's a chance they might it seems prudent for women to eat very low mercury fish.

High Fish Consumption Raises Baby Intelligence But Mercury Lowers IQ Also see the US FDA table Mercury Levels in Commercial Fish and Shellfish.

Share |      Randall Parker, 2007 February 18 02:20 PM  Brain Development

michael vassar said at February 19, 2007 8:14 AM:

Controlled for "SES and other confounding variables". Hopefully that includes parental IQ.

Jim said at February 19, 2007 1:55 PM:

RP- given this apparently strong correlation (intuitively seems like a cause-and-effect) that is an in-vitro environmental effect, doesn't this suggest that the separately-raised twin-studies of iq, etc. (which i know you love to look at as data points) have a potentially serious confounding of genetic differences with in-vitro environmental effects.

I thought of this issue while arguing with a friend about the nature vs. nuture of something else, and this issue of definition confused our discussion quite a bit.

Randall Parker said at February 19, 2007 6:32 PM:


Good catch. I bet they didn't test parental IQ. But the control for SES probably helped quite a bit to reduce genetic influences.

Tj Green said at February 24, 2007 3:11 PM:

Omega 3 reduces cortisol production,therefore reducing stress,depression,and giving us a stronger immune system. I believe everyone would benefit from omega 3 in their diets.

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