Mercury in Shellfish

All right, let’s be honest. It’s hard to keep up with the latest research. And it’s maybe even harder to understand all the nuances, implications and limitations of the studies that we do hear about. Consider what you’ve heard or read about the health benefits of eating seafood and then think about what you’ve heard about the potential risks of elevated mercury in seafood. There’s a lot of information out there, some good, some bad, and that makes it hard to know what to do.

A couple years back, a neighbor of mine, a bright, young woman who had migrated here from the Ukraine, joyfully announced to my wife and me that she was expecting. She and her husband were deliriously happy and eager to learn as much as possible about what they could do as expecting parents to give birth to a healthy child. To my dismay, they had heard about the risks of mercury and made the blanket decision to exclude all seafood from her diet during pregnancy and while nursing. This was despite the documented benefits of eating seafood (a very good source of omega-3 fatty acids, protein and other essential nutrients and low in saturated fat) both for her and her baby. For her, it made the most sense to just cut out seafood completely.

I doubt she’s alone in making this decision, but it’s a decision that ignores what is almost universally accepted: fish and shellfish that are low in mercury are an important part of a healthy diet. If you’re the type who likes lots of information, the U.S. Food and Drug Administration (www.fda.gov) provides a long list of types of fish with their associated mean, median and standard deviation mercury concentrations to help you decide what seafood is best for you. For the rest of us, though, is there a simple way to figure out which seafood is low in mercury?

Fortunately, one simple rule of thumb is that shellfish of all types (with the exception of the American lobster – sorry, Maine) are considered low in mercury. Oysters, shrimp, crab – all harvested within our coastal waters – are listed by the FDA as at least less than 1/10th of the level of concern (1 part per million), and in many cases are listed as having non-detectable levels of mercury. That rule of thumb extends to clams, crawfish, spiny lobsters, scallops and squid (the last one which maybe only geeky shellfish biologists like me consider shellfish).

Before I get hate mail for the species I didn’t mention, there are a whole lot of excellent finfish choices that are low in mercury (catfish, flatfish like flounder, mullet and tilapia, for example), and I personally regularly eat those fish. For those looking to keep it simple, though, shellfish make a smart choice.

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