Fish Q & A

Q: What’s gained by eating fish?

A: Fish are rich in protein, vitamin D, and omega-3 fatty acids, which reduce the risk of heart attack and stroke. The omega-3s might also elevate mood and help prevent certain cancers, cognitive decline, and certain eye diseases. During pregnancy, omega-3s might help in developing the fetus’s brain and visual system.

Q: What could be the harm?

A: Some studies of people who eat lots of fish have linked even low-level mercury exposure in pregnant women and young children to subtle impairments in hearing, hand-eye coordination, and learning ability. Other evidence suggests that frequent consumption of high-mercury fish might affect adults’ neurologic, cardiovascular, and immune systems. Additional contaminants—PCBs and dioxins—found in some fish have been linked to cancer and reproductive problems. Mercury and PCBs can accumulate in people over time.

Q: Are there low-mercury fish?

A: Absolutely. Some popular seafood, including salmon and shrimp, contains relatively little mercury. Alaskan salmon, often sold in cans, tends to be lower in PCBs and possibly other contaminants. See "Lower-mercury choices" for specifics.

Q: Can you get the benefits of fish without eating it?

A: Foods labeled as fortified with the omega-3 fatty acids EPA and DHA are worth considering, though levels in some fortified foods alone might be inadequate. Fish-oil supplements provide omega-3s and are “likely safe” for most people when taken in doses of 3 grams or less per day, according to the Natural Medicines Comprehensive Database, which is compiled by an independent research group. But talk with your doctor or pharmacist before taking fish-oil supplements because they can have side effects and might interact with medications.

If you decide to take a supplement, choose one labeled with a “USP Verified” seal. Products bearing that label meet standards for purity and potency set by the U.S. Pharmacopeia, a nongovernmental authority, and have what the USP considers acceptable limits of contaminants, including PCBs. For a list of products that have been verified by the USP, go to www.uspverified.org.

Q: Which low-mercury fish are harvested sustainably?

A: Alaskan salmon, farmed clams, pink shrimp from Oregon, sardines from the U.S. Pacific, and tilapia farmed in the U.S. are abundant, well managed, and fished or farmed in ways that minimize harm to the environment, according to research conducted by the nonprofit Monterey Bay Aquarium’s Seafood Watch Program.