The risks associated with fish consumption outweigh potential benefits, say dietitians and doctors with the Physicians Committee for Responsible Medicine (PCRM). PCRM nutrition experts are available for comment in response to a new report commissioned by the National Oceanic and Atmospheric Administration on the topic. The report, conducted by the National Academies of Science, is being released on October 17 in conjunction with another study on fish from the Harvard School of Public Health.

"The problems go beyond mercury and other contaminants," says Hope Ferdowsian, M.D., M.P.H., a public health specialist with PCRM. "Fish are surprisingly high in cholesterol and saturated fat—that is “bad” fat, which accounts for 15 to 30 percent of fish fat. Ounce for ounce, shrimp and lobster are much higher in cholesterol than steak."

While fish does provide high levels of omega-3 fatty acid, a "good" fat thought to help with cardiovascular health, most consumers don't realize that all fats have the same caloric content. “Good” fats are just as likely to help one pack on the pounds as bad fats. Only a portion of the fat in fish is omega-3; much of the remaining fat is saturated. Chinook salmon, for example, derives 55 percent of its calories from fat, and swordfish derives 30 percent. About one-quarter of the fat in both types of fish is saturated.

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Fish and shellfish are also significant sources of cholesterol. Three ounces of shrimp have 130 milligrams of cholesterol; in comparison, a 3-ounce steak has about 80 milligrams. healthren.com

The most nutritious sources of omega-3s are plant-based foods, including green leafy vegetables, legumes, soybeans, and walnuts. healthren.com