February 3, 2012
Pregnant Women Who Consume Low-Mercury Fish Have Smarter, More Social Offspring
Can pregnant women improve their progeny’s intelligence by eating fish? The answer is yes, as long as that fish is not polluted with high levels of mercury. A study recently submitted to the American Journal of Clinical Nutrition revealed that infants born to mothers who consumed more fish during pregnancy score higher in verbal intelligence and fine motor skill tests, and present an increased prosocial behavior.
The study was conducted within the framework of the NUTRIMENTHE project (“Effect of diet on offspring’s cognitive development”), which received funding of 5.9 million Euros from the European 7th Framework Programme (7PM) and coordinated by the University of Granada professor Cristina Campoy Folgoso.
Fish oil is the primary source of long-chain Omega-3 fatty acids as docosahexaenoic acid (DHA), the main component of brain cell membranes. The European Commission has confirmed and supports the healthy effects of DHA as “it contributes to the normal development of the brain and eye of the fetus and breastfed infants”.
The NUTRIMENTHE project is focused on the effects that genetic variants and maternal fish intake have on the offspring’s intellectual capacity. The researchers mainly focused on polymorphisms in the fatty acid desaturase (FADS) gene cluster that encodes the delta-5 and delta-6 desaturase enzymes involved in the synthesis of long-chain fatty acids of the series omega-3 and omega-6.
Although the project did not incorporate toxic levels of mercury in specific species of fish, it remains a serious problem in many parts of the world. Pollution causes the toxic metal mercury to accumulate in fish and seafood, in the form of methylmercury.
"EFSA recommends that women of childbearing age...select fish from a wide range of species, without giving undue preference to large predatory fish such as swordfish and tuna," it said in a statement. However, there are several other species of fish such as marlin, grouper, mackerel, bass, bluefish, ocean trout, halibut and several other which presented usually high levels of mercury when tested. Here Are The Top 10 Best and Worst
The researchers collected blood samples from 2000 women at 20 gestational weeks and from the umbilical cord of the infant at birth, and analyzed concentrations of long-chain fatty acids of the series omega-3 and omega-6.
Then, they determined the genotype of 18 polymorphisms in the FADS gene cluster. The aim of this study was to assess the effects of maternal fish intake -as a source of Omega-3 and Omega-6 fatty acids- on fetal development, and to determine how the different genotypes affect long-chain fatty acid concentrations in the fetus.
Dr. Pauline Emmett (University of Bristol), Dr. Eva Lattka (Helmholtz Zentrum Munchen, the German Research Center for Environmental Health) and their research teams have determined how FADS gene cluster polymorphisms affect long-chain polyunsaturated fatty acid concentrations in women during pregnancy.
According to the researchers, fatty acid concentrations in umbilical cord blood depend on maternal and offspring genotypes. Accordingly, maternal genotypes are mainly related with omega-6 fatty acid precursors, and offspring genotypes are related with the more highly elongated fatty acids of the omega-6 series. The study also revealed that concentrations of docosahexaenoic acid (DHA) of the Omega-3 series -main component of brain cell membranes- depend on maternal and offspring genotypes. Dr Lattka states that “the fetal contribution of long-chain polyunsaturated fatty acids of the omega-6 series is more relevant than expected; fetal DHA concentrations depend on maternal and fetal metabolism”, and concludes that “the amount of DHA transmitted to the fetus through the placenta might be crucial for fetal development”.
In a previous study, this research team proved that fish intake during pregnancy is correlated with the IQ in 8-year old children. But, what causes that effect? The study revealed that fish intake is correlated with maternal blood DHA concentrations. However, it has not been clarified whether maternal DHA concentrations are directly correlated with the offspring’s IQ. The NUTRIMENTHE project --which is expected to conclude in 2013- is aimed at elucidating this question.