The benefits of eating fish on heart attack risk is mostly due to the effects of omega-3 fatty acids. But, fish also contains methylmercury, which may increase the risk of heart attack.

Researchers at Umea University, in Sweden, determined how eating fish and red blood cell concentrations of mercury and selenium are related to the risk of a heart attack and whether omega-3 fatty acids are protective.

First, the details.

  • More than 900 Swedish men and women answered questionnaires about the amount of fish in their diet.

And, the results.

  • People whose red blood cells showed elevated amounts of mercury did not have a higher risk of cardiac problems.
  • People whose red blood cells had elevated traces of selenium appeared to be at increased risk of sudden cardiac death, although the number of people was small.

The bottom line?

FDA tells us, “Fish and shellfish are an important part of a healthy diet. Fish and shellfish contain high-quality protein and other essential nutrients, are low in saturated fat, and contain omega-3 fatty acids. A well-balanced diet that includes a variety of fish and shellfish can contribute to heart health and children’s proper growth and development.”

FDA recommends that we follow 3 recommendations.

  • Don’t eat shark, swordfish, king mackerel, or tilefish because they contain high levels of mercury.
  • Eat up to 12 ounces (2 average meals) a week of a variety of fish and shellfish that are lower in mercury (shrimp, canned light tuna [not albacore), salmon, pollock, and catfish).
  • Check local advisories about the safety of fish caught by family and friends in your local lakes, rivers, and coastal areas.

1/26/11 20:05 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.