Quinn on Nutrition: Update on seafood and mercury

May 22, 2017

What’s the deal with mercury in seafood? Health experts tell us to eat more fish for the beneficial effects of omega-3 fatty acids, which are critical for brain and eye development during pregnancy and young childhood. Yet fish can also contain mercury — a metal in the environment that is toxic to the brain and nervous system.

In January of 2017, the US Food and Drug Administration (FDA) along with the Environmental Protection Agency (EPA) issued updated advice for how much and what types of fish are safe for us to consume, according to an article on this topic by registered dietitian nutritionist Eleese Cunningham in the Journal of the Academy of Nutrition and Dietetics. Here are some highlights:

Bigger fish contain more mercury. Makes sense. Mercury occurs naturally in soil and water and traces are found in all fish. But it’s the older, larger predatory fish — those that eat smaller fish — that accumulate more mercury. Fish known for their high mercury levels are best avoided by pregnant and breastfeeding women and young children, says the FDA. They include shark, swordfish, orange roughy, bigeye tuna, marlin, king mackerel and tilefish from the Gulf of Mexico. (Tilefish from the Atlantic Ocean have much lower levels of mercury.)

The benefits of eating fish far outweigh the risks. Omega-3 fatty acids in fish, particularly the one called docohexaenoic acid or DHA, is vital for optimal development of the eyes and brain. Yet a recent analysis found that 50 percent of pregnant women eat far less seafood than the recommended 8 ounces a week.

There are safe ways to reap the nutritional benefits of fish and minimize mercury exposure as well. Revised guidelines by the FDA include a chart of "Best" and "Good" fish choices based on mercury content.

"Best" choices includes cod, crab, salmon, shrimp, tilapia and canned light tuna. "Good" choices include halibut, Monkfish, ocean striped bass, albacore/white tuna and yellowfin tuna. Find the complete chart at

Pregnant and breastfeeding women, young children and women of childbearing age (16 to 49 years) are advised to eat 2 to 3 servings a week from the "Best Choices" list or 1 serving a week from the "Good Choices" list. (One serving is about the size of your palm, or about 4 ounces for adults and 2 ounces for children.)

And here’s a question: What’s the difference between albacore (white) tuna and canned light tuna? Albacore, or white tuna, is larger and lives longer than the fish generally used in canned light tuna, says the EPA. Canned light tuna is often a mix of a variety of smaller tuna species such as skipjack.

And remember, says the FDA, "fish" refers to all fish, including shellfish. Enjoy a variety.



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