The nutritional benefits of eating seafood—a high-quality protein source that's low in saturated fat and loaded with nutrients such as vitamin D and selenium—outweigh potential risks from contaminants, according to two recent studies.

In "Seafood Choices: Balancing Benefits and Risks," a committee from the Institute of Medicine of the National Academies (IOM) noted that much of the evidence about seafood's benefits is preliminary. However, it did find that eating seafood reduces the risk of heart disease. And pregnant women who consume omega-3 fatty acids from fish may benefit from a longer gestation and give birth to infants with better vision and brain development.

Researchers from the Harvard School of Public Health recently came to similar conclusions (Journal of the American Medical Association, 2006, vol. 296, no. 15). Examining evidence from published reports, they found that consuming one or two servings of fish per week reduced the risk of coronary death by 36 percent and total mortality by 17 percent. Also, DHA (docosahexaenoic acid) in fish seems to support early neurodevelopment.

But these benefits don't come without risk. Consuming seafood may expose people to small amounts of methylmercury, organic pollutants (dioxins and polychlorinated biphenyls), or microbial contaminants.

According to the IOM committee, consumers can minimize risks by following accepted dietary guidelines—eating more low-contaminant seafood (such as catfish and wild Alaskan salmon) and limiting intake of higher-contaminant seafood (including swordfish, shark, tilefish, king mackerel). Some populations, including women who are or may become pregnant, may want to examine their choices more conservatively.

The Harvard researchers also concluded that the nutritional benefits of eating fish outweigh potential carcinogenic effects of contaminants. Although they noted that methylmercury may adversely affect early neurodevelopment, they still recommended twice-weekly fish consumption for women of childbearing age—as long as they limit intake to a few selected species.

"While it's human nature to focus on risks, the benefits should not be forgotten," says lead author Dariush Mozaffarian, MD, DrPH. "Based on the evidence, the health benefits of fish intake far outweigh the risks, and seafood is likely the single-most important food one could eat for good cardiovascular health."