Tuna tops in mercury exposure for fish eaters

Consumption of tuna, the most commonly eaten fish in the United States, accounts for one-third of mercury exposure from eating seafood, a new study shows.

The study is in this month's issue of the journal Environmental Research, and shows that mercury content varies widely depending on the variety of fish. In all, 51 varieties of seafood are ranked based on mercury content.

Salmon, catfish and flounder have low levels while bluefin tuna and swordfish are among the varieties that have the highest levels. Shellfish and crustaceans such as clams and crabs were listed with low mercury levels, according to the study.

But the National Fisheries Institute's registered dietitian Jennifer McGuire says a study that looks only at mercury levels in seafood undermines the nutritional value of fish as a whole. Fish and other seafood are rich in omega-3 fatty acids and other nutrients that are good for both the heart and brain. Making healthy choices isn't that hard.