Mercury fears may be overblown

Concerns over mercury exposure have resulted in warnings from the FDA to limit how much fish we eat, especially for women of childbearing years, out of fear that mercury causes harm to the developing nervous system of a fetus. However, a 30-year study* of pregnant women who ate an average of 12 meals per week containing fish (the FDA recommends no more than two average meals per week of fish) [1]  shows there may be little to worry about.

“These findings show no overall association between prenatal exposure to mercury through fish consumption and neurodevelopmental outcomes,” said Edwin van Wijngaarden, Ph.D., and 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 findings Dr. Wijngaarden refers to have to do with polyunsaturated fatty acids (PUFA)—nutrients in the family of omega-3 fatty acids—that appear to offset the risks associated with mercury exposure.

The study [2] followed 1,500 mothers and their children. During the pregnancies, samples were taken from the expectant mothers to measure their mercury exposure. At 20 months following birth, children underwent tests designed to measure behavior, communication and motor skills.

Researchers found that mercury exposure did not correlate with lower test scores. They did find that children born of mothers who had higher levels of n3 PUFA (of the omega-3 family found in fish) during pregnancy performed better on certain tests. Children born of mothers with higher levels of n6 (of the omega-6 family found in other meats and cooking oils) did poorer on tests measuring motor skills.

The fatty acids in fish (n3) are known to have anti-inflammatory properties, compared to n6, which can promote inflammation. One of the ways in which mercury inflicts damage is through oxidation and inflammation. It appears that not only does n3 provide more benefit in terms of brain development, but that these compounds may also counteract the negative effects of mercury.

If you are inclined to eat more fish, it would probably still be wise to avoid fish known for containing high levels of mercury such as swordfish, tilefish, king mackerel and shark. [3]

*The Seychelles Child Development Study — a partnership between the University of Rochester Ulster University, and the Republic of Seychelles Ministry of Health and Education — is one of the longest and largest population studies of its kind. The Seychelles, a cluster of islands in the Indian Ocean, has proven to be the ideal location to examine 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.

[1] http://www.fda.gov/Food/ResourcesForYou/HealthEducators/ucm083324.htm
[2] http://ajcn.nutrition.org/content/early/2015/01/21/ajcn.114.100503
[3] http://www.fda.gov/Food/ResourcesForYou/HealthEducators/ucm083324.htm

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Kellye Copas

By Kellye Copas

Staff writer Kellye Copas has several years experience writing for the alternative health industry. Her background is in non-profit fundraising, copywriting and direct mail and web marketing.