Eating fish can be a great choice. It's an excellent, low-fat source of protein and other nutrients including omega-3 fatty acids, which may help protect your heart, and if you're pregnant, boost your baby's brain development. But there's a catch. Some seafood contains high levels of a form of mercury, called methylmercury. Mercury can damage the brain, and it can damage the nervous system, especially when that exposure occurs in the womb.
The government advises young children, and women who are pregnant, breast-feeding, or might become pregnant, to avoid the four fish with the highest mercury levels: swordfish, shark, king mackerel, and tilefish from the Gulf of Mexico. The Food and Drug Administration is also considering adding marlin and orange roughy to the list.
Consumer Reports' food-safety experts agree but have additional concerns about tuna. Tuna accounts for 40 percent of our mercury exposure. Most of that is from canned tuna. Fresh tuna, popular in sushi, can also be especially high in mercury. To be safe, Consumer Reports recommends that pregnant women not eat any tuna at all. And children and anyone who eats a lot of fish should really limit the amount of tuna they eat.
All of this discussion doesn't mean you should skip eating fish. In fact, for the first time, the FDA has just said how much fish women who are pregnant, breast-feeding, or trying to get pregnant should be eating. The minimum is at least 8 ounces per week of a variety of fish lower in mercury. Some good choices include: Wild and Alaska salmon, canned or fresh; shrimp; sardines; tilapia; scallops; oysters; and squid.