Balancing the Risks and Benefits of Fish

Two reports released today tackle concerns about fish contamination, coming out strong that Americans should eat more fish.

The reports, from the Institutes of Medicine and the Journal of the American Medical Association, emphasize the need to balance the health benefits of eating fish against the risks of pollutants that contaminate waters and the fish that live in them.

According to the available evidence, eating fish helps your health more than it hurts it.

Eating a few servings of fish a week can reduce the risk of coronary death by 36 percent and the overall risk of death by 17 percent, according to JAMA's report.

The authors of the studies say that a little bit of fish is all you need.

"If someone eats one or two servings per week of oily fish, they're getting most of the benefit," says Dr. Dariush Mozaffarian at the Harvard School of Public Health and one of the study's authors. "They don't need to eat four or five or 10 servings per week to get the benefit."

Too much fish is something some might want to avoid.

Despite today's reports that the benefits of eating fish outweigh the risks, experts worry about methylmercury contamination in fish. Methylmercury can cause brain and spinal cord damage. How bad the damage is depends on how much poison gets into the body.

Methylmercury contamination has less to do with the fish itself and more to do with water contamination. Toxins like mercury that are sometimes found in our waters are also sometimes found in our sea creatures.

Some stores even post signs to warn consumers. And today's IOM report agrees with current government guidelines and warns that pregnant women, nursing mothers and children under 12 should avoid fish that contains high mercury levels, such as shark, swordfish, tilefish and king mackerel.

For the rest of us, the best way to avoid contamination is to eat a variety of fish.

"Sampling broadly from the fish available is probably a strategy that will maximize the benefit and minimize the risk," says IOM report co-author David Bellinger at the Harvard School of Public Health.

Because seafood supplies and cultivation practices change constantly, it would be difficult for federal agencies to develop a list of "good fish" and "bad fish" that would stay current over time.

But according to the IOM report, the risks and benefits for broad categories of fish are pretty straightforward.

For example, the report warns that predatory fish with long life spans -- such as swordfish, shark and tilefish -- contain levels of methylmercury that are too high for pregnant and breast-feeding women.

Also, fatty fish, such as salmon, provide the highest amounts of omega-3 fatty acids and have a lower methylmercury burden than some lean fish, but those fish also contain higher levels of saturated fat and cholesterol.

So pay attention to the kind of fish you eat. "Seafood is likely the single most important food one can consume for good health," Mozaffarian said.

ABC News Correspondant Lisa Stark contributed to this piece