The Fish Paradox: Are Maternal Omega-3 (n-3) DHA and Selenium (Se) Intake Protective Against Negative Effects of Methylmercury Exposure on Infant Cognitive Development?

Abstract

Similarly, negative effects of higher levels of methylmercury exposure, have been demonstrated in the China only after controlling for n-3 DHA [14], although positive benefits of n-3 DHA were diminished at high maternal levels of mercury in cohorts from the Seychelles and U.S [6,15]. Results from the large British ALSPAC Study showed that mothers who consumed the greatest amount of n-3 DHA from fish throughout pregnancy and breastfeeding gave birth to babies who performed better on a wide variety of neurocognitive tests compared to the least amount of DHA. Effects of fish intake on cognitive development from the longitudinal Seychelles Child Development Nutrition Study have largely been attributable to the maternal n-3 DHA status which parallels dietary seafood intake [9,15,16]. The potential of nutrients to modify mercury toxicity remains an area of great interest. Current evidence suggests that selenium may mitigate the negative effect of methyl mercury and that the benefits of n-3 DHA outweigh the risks of consumption of most seafood during pregnancy and lactation. The greatest cognitive benefits are derived from maternal consumption of seafood which is highest in n-3 DHA and low in methylmercury. The modulating effect of selenium, although clear in animal models, has not been well documented in humans. Further research is needed to address this question.