Fable: Pregnant Women Should Eat Lots of Fish, Because the Benefits to Their Babies’ Brains Will Far Outweigh Any Risks from Mercury

Facts: Fish consumption does provide essential nutrients for brain development, but the evidence strongly suggests that the damage done by mercury to the developing brain is significantly greater than the benefits offered by fish nutrients. Women of childbearing age should eat fish, but should also be particularly aware of mercury risks and choose low-mercury fish. (See “Who should be concerned?”).

Mercury damage to prenatal brain development has been documented in epidemiological studies of populations with high-fish diets, in the Faeroe Islands and in New Zealand. Two recent studies, in Boston and New York City, tested children born to women who ate typical US diets, averaging just over one fish meal per week. Even in this typical American population, the children whose mothers had eaten higher-mercury fish showed adverse effects of mercury on brain development. These studies also showed beneficial effects for brain development of higher fish consumption, reinforcing the need for pregnant women to choose low-mercury fish.

Several low-mercury fish, including salmon, herring, tilapia, anchovies and sardines, are also rich in omega-3 fatty acids, fish nutrients essential for brain development.

While fish consumption has significant benefits for both individual and public health, many fish stocks are overfished, and fishing practices are often unsustainable. Most of the nutrients in fish can also be obtained from non-fish (plant) sources. These important issues are outside the scope of this discussion of mercury in fish, but to read more about them, visit the Got Mercury web site.