The benefits of fish consumption during pregnancy may override the much-feared risks of mercury exposure, according to a new study published in the American Journal of Clinical Nutrition.
In fact, the findings suggest that the nutrients found in fish have properties that protect the brain from the potential toxic effects of mercury.
Previously, researchers had compared the ‘health benefits vs mercury’ dilemma as a kind of biological horse race, with the developmental benefits of nutrients in fish outpacing its possible harmful effects of mercury.
However, the new research indicates that this relation is far more complex. It appears that certain compounds found in fish — specifically polyunsaturated fatty acids (PUFA) — may actively counteract the damage that mercury causes in the brain.
The study, which is the culmination of three decades of research in the Seychelles, a cluster of islands in the Indian Ocean, has found that high levels of fish consumption by pregnant mothers (an average of 12 meals per week) do not result in developmental problems in their children.
“These findings show no overall association between prenatal exposure to mercury through fish consumption and neurodevelopmental outcomes,” said Edwin van Wijngaarden, Ph.D., associate professor in the University of Rochester Department of Public Health Sciences and a co-author of the study.
“It is also becoming increasingly clear that the benefits of fish consumption may outweigh, or even mask, any potentially adverse effects of mercury.”
The research is timely as the U.S. Food and Drug Administration and international agencies are in the process of revisiting fish consumption advisories.
The FDA’s current guidelines — which recommends that pregnant women limit their consumption of certain fish to twice a week — was established because of the known risk of high level mercury exposure on childhood development.
“This research provided us the opportunity to study the role of polyunsaturated fatty acids on development and their potential to augment or counteract the toxic properties of mercury,” said Sean Strain, Ph.D., a professor of Human Nutrition at the Ulster University in Northern Ireland and lead author of the study.
“The findings indicate that the type of fatty acids a mother consumes during pregnancy may make a difference in terms of their child’s future neurological development.”
The study followed more than 1,500 mothers and their children. When the children turned 20 months, they underwent a battery of tests designed to measure their communication skills, behavior, and motor skills. The researchers also collected hair samples from the mothers at the time of their pregnancy to measure the levels of prenatal mercury exposure.
The researchers found that mercury exposure did not correlate with lower test scores. This finding tracked with the results of previous studies by the group — some of which have followed children in the Seychelles into their 20s — that have also shown no association between fish consumption and subsequent neurological development.
“It appears that relationship between fish nutrients and mercury may be far more complex than previously appreciated,” said Philip Davidson, Ph.D., the principal investigator of the Seychelles Child Development Study, a professor emeritus at the University of Rochester, and senior author of the study.
“These findings indicate that there may be an optimal balance between the different inflammatory properties of fatty acids that promote fetal development and that these mechanisms warrant further study.”
The Seychelles has proven to be the ideal location to study the potential health impact of persistent low-level mercury exposure. The nation’s 89,000 residents consume fish at a rate 10 times greater than the populations of the U.S. and Europe.