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The Truth About Seafood

Is too much fish putting your health in deep water?
By Cynthia Sass, MPH, MA, RD, CSSD

Many of my athlete clients regularly eat sushi and fish, and consider seafood to be a healthy protein choice. But too much seafood, or even the wrong types, can dramatically up your exposure to mercury, a heavy metal found in our oceans that accumulates in the bodies of fish.

For pregnant women, the dangers of mercury have been well established. Even small amounts of the metal can interfere with fetal brain development. But we’re just starting to learn about the risks in adults, and the research is concerning. A recent study published in the American Academy of Neurology found that among 518 people, those in the top 25% for annual mercury intake had a risk of ALS that was double that of subjects with the lowest mercury exposure. ALS is the progressive neurological disease also referred to as Lou Gehrig’s disease. A previous study, from the University of South Florida, found that despite having superior fitness, adult men and women with the highest mercury levels had impaired executive functions, including response time, and shifting attention quickly and accurately, critical skills for athletic performance. Indiana University scientists also found that when younger adults were exposed to higher levels of mercury, their risk of developing type 2 diabetes later in life jumped by 65%.

So should you swear off seafood to skirt the issue? No. Forgoing fish isn’t practical or necessary. Seafood is an excellent source of lean protein, and the best choices are also packed with key nutrients, including omega-3 fatty acids. These good-for- you fats have been linked to anti-inflammation, improved cognitive abilities, anti-aging, muscle development, and reduced muscle soreness – key benefits for athletic performance and recovery. The solution is to get savvy about your seafood regime. Follow these four simple rules of thumb to reap the benefits of nutrient-rich fish, without the risks linked to excess mercury.

  • Make high omega-3 fish your primary go-to at home and when dining out. These include wild Alaskan salmon, sardines, rainbow trout, and Atlantic mackerel.
  • Limit total seafood intake to 12 ounces per week. Other low mercury options (that aren’t high in omega-3s) include shrimp, scallops, clams, sole, and Atlantic cod.
  • Eliminate or strictly limit seafood known to be high in mercury. These include: orange roughy, shark, swordfish, king mackerel, marlin, gulf tilefish, freshwater trout, Chilean seabass, grouper, and Bluefin tuna.
  • Note: if you eat any of these varieties, limit it to no more than one portion per week, with no other seafood consumed within seven days. Have your mercury level checked by your physician. Mercury does leave the body over time, but knowing if your level is currently high is critical for preventing a chronically high exposure and guiding your food choices.

Sushi Alert
Rutgers University researchers analyzed sushi from New Jersey, New York City, and Chicago, to test for mercury. While the levels varied, overall the mercury content in the samples exceeded the recommended limits. The worst offender was tuna sashimi, while eel, crab, and salmon ranked lowest in mercury.

Cynthia Sass is a nutritional consultant to the New York Yankees and Brooklyn Nets. She can be reached at

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