The Crazy Way Omega-3s Could Cancel Out The Mercury In Your Seafood

Omega-3s fight mercury in seafood
Ira Heuvelman Dobrolyubova/Getty

If you’re freaked out by mercury in seafood, we have some good news. A recent study in the American Journal of Clinical Nutrition found that the nutrients in certain fish like DHA, an omega-3 fatty acid, may help protect the brain from the potential neuro-toxic effects of mercury. 

To reach this conclusion, researchers followed more than 1,500 mothers and their children on the Seychelles islands in the Indian Ocean, where fish consumption can be 10 times greater than in the U.S. First, researchers measured the mothers’ levels of mercury and omega-3 fatty acids during pregnancy. Then, after the moms gave birth, researchers tested their children’s communication skills, behavior, and motor skills at 20 months. What they found: Mercury exposure did not correspond with lower test scores, but higher omega-3 levels did lead to better test scores.

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Consumption of certain fish seems to be positive overall because the benefits of the omega-3s outweigh the adverse effects of the mercury, says study author Edwin van Wijngaarden, PhD. How’s this possible? Mercury damages cells through oxidation and inflammation, while omega-3s are anti-inflammatory, countering the effect, says van Wijngaarden. 

While there's not enough information to say for certain that this effect will extend to adults, van Wijngaarden notes that eating fish provides cardiovascular and cognitive benefits for adults because of the protective effect of omega-3 and other nutrients such as selenium. So one could hypothesize, he says, that we would find similar associations with these nutrients and their interaction with mercury.

To pick the safest seafood, choose options low in mercury and high in omega-3s such as salmon, anchovies, trout, and certain canned light tunas. Avoid or limit your intake of the highest mercury fish: shark, swordfish, king mackerel, and tilefish. If you love canned tuna, look for brands like Wild Planet that source younger (i.e., lower mercury) fish and cook them just once, in the can, to preserve omega-3s—two practices that are uncommon for conventional brands.

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