Balancing the Risks and Benefits of Fish Consumption

Most Americans know that eating fish is good for their health. Studies from the past 2 decades have repeatedly linked the consumption of fish—especially fish that is high in ω-3 fatty acids—with healthier hearts in the aging population (1). Scientists have also found associations between fish consumption and a reduced risk for stroke, dementia, asthma, kidney disease, and diabetes. Americans have responded to the news: U.S. fish consumption per capita increased 50% since 1980, according to the U.S. Department of Agriculture. Consumption of salmon alone, the country's third most popular fish, increased 23% between 1987 and 1999.

But Americans have heard less about, and perhaps paid less attention to, various health warnings associated with fish consumption. Studies have linked overconsumption of certain fish (particularly popular ones such as swordfish, tuna steaks, Chilean sea bass, and some kinds salmon) to neurologic deficits, cancer, autoimmune and endocrine disorders, and even some heart disorders. The risks stem mainly from 2 toxins: mercury, which accumulates over the lifetime of larger, longer-living fish, and polychlorinated biphenyls (PCBs), which are found in fish living in polluted waters and in some farmed fish.

The idea that certain fish can be both beneficial and harmful is difficult for many people to understand, and they're not getting much help, according to environmental health experts. The federal government doesn't provide straightforward guidance: For instance, it has recommended that people eat salmon because it is high in ω-3 fatty acids without mentioning that farmed salmon commonly contains high levels of PCBs. Grocery stores seldom label fish that are likely to have a high content of toxins. Consumers must read state advisories to learn which noncommercial local fish are safe to eat.

Many Americans have simply ignored the warnings about fish, perhaps holding the popular idea that lots of food today …