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Good Fish, Bad Fish 8/8/06

Good Fish, Bad Fish

Some health experts, according to this story, worry there’s enough conflicting advice about seafood to make the public avoid fish altogether.

William Lands, a retired National Institutes of Health researcher who has studied the healthy fats found in fish, was quoted as saying, “It’s a shame that people are running away from seafood at a time when it gives so many benefits.”

Walter Willett, professor of nutrition at the Harvard School of Public health, was quoted as saying the benefits of eating seafood “are likely to be at least 100-fold greater than the estimates of harm which may not exist at all,” and that “the kinds of levels of contaminants that are being talked about are not a reason for people to reduce their fish intake.”

Rich in omega-3 fatty acids, a healthy kind of fat, seafood is known to help protect the heart, the brain and the joints.

Reporting in the August 2006 Journal of the American College of Cardiology, researchers from the Harvard-affiliated Channing laboratory found that increased fish consumption is linked with a lower risk of irregular heartbeat, which can lead to death. These findings fit with other studies that suggest eating at least two meals of seafood per week has health benefits, including a reduced risk of stroke.

The story says that the health advantages of eating seafood are sufficiently clear that the U.S. Dietary Guidelines, the American heart Association, the National Academy of Sciences, and the National Heart, Lung, and Blood Institute recommend fish for at least two meal a week (unless it’s deep-fried).

But concerns about mercury and other potential risks continue to muddy the waters. Both the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) warn young children, women who might become pregnant and those who are pregnant or nursing to completely avoid eating shark, swordfish and king mackerel and to limit albacore (“white”) tuna, all of which can be high in mercury.

Mercury occurs naturally in the environment and is also spewed into the air by industrial emissions, particularly from power plants. As the mercury drifts down, it accumulates in streams and oceans, where bacteria convert it to a toxic form of the chemical called methylmercury, which is then absorbed by fish.

The higher a fish is on the food chain, the more mercury it accumulates. Experts have worried that this could be damaging, particularly if the mercury crosses the placenta and passes into the fetal brain, where it could affect hearing and intelligence.

As with many things in science, there is controversy about what levels of mercury are safe. Whether fish is farm-raised or wild, “it would be unfortunate if people cut their consumption,” Willett says. Neither the mercury concern nor the PCB contamination levels are “enough for people to reduce their fish intake.”

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