The Scoop on Food

Good News About Fish & Mercury

There's a reason to relax—and put fish back on your plate!

Cooked salmon on plate with lemon slices svariophoto/Shutterstock
You know fish is good for you and your kids. It's full of protein and omega-3 fats that are healthy for hearts and developing brains and vision. But the warnings about mercury contamination can be downright scary, making you wonder whether it's even worth it. That may be why pregnant women currently eat less than two ounces of it a week—that's less than one serving!

There's reason to relax and put seafood back on your plate. According to research published in the journal Toxicology, fish actually comes with its own natural defense against mercury toxicity in the form of the mineral selenium. How it works: Selenium is an essential mineral that's especially important for brain health. Mercury can bind to selenium in the body and form an unbreakable bond that keeps selenium from performing its job in the brain (that's how mercury causes harm). But if you're eating selenium-rich foods like ocean fish, none of these effects occur, says Nick Ralston, Ph.D., a research scientist at the University of North Dakota. The mercury-selenium package is ushered out of the body through urine, helping clear the body of mercury.

Other than sharks and large swordfish, virtually all ocean fish are much higher in selenium than mercury. In fact, they're among the richest sources of selenium, and they pack omega-3 fatty acids for healthy brain growth and function. Studies have found that children of mothers who eat ocean fish during pregnancy have IQs that are 4-6 points higher than children whose mothers avoid eating seafood, says Ralston.

The FDA advisory is currently being revised, but the current draft recommends that pregnant women eat 8-12 ounces of low-mercury fish per week (about 2-3 servings). Kids should have 2-3 child-sized portions a week. "The nutrients in ocean fish are so important, I believe these recommendations should read 'eat no less than two servings per week during pregnancy'," says Ralston.

Varieties low in mercury include salmon, shrimp, pollock, tuna (light canned), tilapia, catfish, and cod. There tends to be more mercury in certain types, which is why pregnant women and children are still advised to avoid eating shark, swordfish, tilefish, and king mackerel. For varieties that you or others catch in rivers, streams, and lakes, more work needs to be done to figure out their mercury-to-selenium ratios, so for now it is best to limit portions of these to once a week.

Sally Kuzemchak, MS, RD, is a registered dietitian, educator, and mom of two who blogs at Real Mom Nutrition. You can follow her on Facebook, Twitter, Pinterest, and Instagram. She collaborated with Cooking Light on Dinnertime Survival Guide, a cookbook for busy families. In her spare time, she loads and unloads the dishwasher. Then loads it again.