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Seafood and mercury levels: What you should know

These days there are two seemingly contradictory statements about seafood consumption. If you like eating seafood, you might have found yourself caught directly between the two. The first claim is that we should eat it to stay healthy, and the second claim is that many fish are unsafe to eat due to high mercury levels. So what’s the truth?

How mercury levels in seafood may impact health

All humans are exposed to at least a low level of mercury, and this isn’t necessarily unsafe. But some people are exposed to high levels of mercury that, ultimately, can be dangerous. Eating certain types of seafood is the most common way to be exposed to mercury, which is why you may have been warned against it.

The dangers of mercury exposure

Health effects vary depending on how much mercury a person is exposed to, and for how long, as well as that person’s individual characteristics. For the most part though, high mercury levels can damage the central nervous system, resulting in sensory and coordination problems, among other possible effects. Women with high mercury exposure while pregnant are also more likely to have babies that eventually have developmental problems or cerebral palsy.

Risks vs. reward of eating fish

Nearly every kind of fish contains mercury (and are often contaminated with more). But herein lies the (spicy lemon) rub: fish also provide a great array of nutrients for the human body. According to the U.S. Food and Drug Administration, fish is a valuable source of protein, vitamins and minerals, omega-3 fatty acids, and, depending on the species, vitamin D.

Smart eating tips

  • Avoid: Some fish are better off completely avoiding, due to their high mercury content. This is especially true if you’re considering getting pregnant, or if you’re already pregnant, breastfeeding, or feeding small children. These fish include: swordfish, king mackerel, shark, tilefish from the Gulf of Mexico, marlin, orange roughy, ahi tuna, and bigeye tuna.
  • Reduce: Adults should eat no more than two servings of light tuna per week, and children should only be eating about four ounces per week. Canned light tuna isn’t high in mercury, but it’s better to eat healthier fish that are lower in mercury. Another way to make your seafood choices healthier is to eat smaller fish and certain types of shellfish, like anchovies and scallops, as opposed to the big ones. Bigger fish tend to have more mercury because they consume the smaller ones, and ingest all of the mercury that their prey has eaten, and the cycle continues.
  • Simplify: If you’re a sushi savant, ask for your order to come without tuna, mackerel, sea bass, or yellowtail.
  • Choose: Of course, certain kinds of fish are not only tasty, but highly nutritious. Choose to eat fish and shellfish with low mercury levels, which include salmon, tilapia, scallop, clam, oyster, shrimp, anchovies, catfish, haddock, and cod.

Mercury: The bottom line

Many types of fish and shellfish are great sources of nutrients for adults and children alike, and should be enjoyed! But mercury exposure poses a real threat to those who eat fish. To keep your mercury levels low, choose fish that have a very low mercury content. If you’re considering getting pregnant or are already pregnant, you should definitely avoid the kinds of fish that are high in mercury.

  • “2017 EPA-FDA Advice about Eating Fish and Shellfish.” United States Environmental Protection Agency, 2017. Web. Accessed 10/26/17. Available at
  • “A Guide to Protecting Your Family’s Health.” NRDC. Natural Resources Defense Council, May 2006. Web. Accessed 10/26/17. Available at
  • “Mercury in seafood.” Environmental Defense Fund, n.d. Web. Accessed 10/26/17. Available at

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