Pregnancy

Yes — in moderation. Seafood is an excellent source of nutrients, but it can contain contaminants (a fact that's received a lot of alarming attention in the press recently). These chemicals include methyl mercury and, to a lesser extent, dioxins, PCBs, and pesticides. When eaten in amounts higher than those found in most commercially sold seafood, these contaminants have been linked to developmental delays in children who were exposed to them before birth.

Even so, there's no reason to ban seafood from your diet — though it's wise to avoid large and predatory fish (those that feed on other contaminated fish), which tend to contain the highest levels of pollutants — specifically shark, king mackerel, swordfish, and tilefish.

Experts are still haggling over the safety of tuna. Because they come from bigger fish (which have had more time to accumulate toxins in their system), tuna steaks and canned albacore tend to contain higher levels of contaminants, so it's best to avoid tuna steaks altogether for now and to limit your consumption of albacore to no more than 6 ounces a week. Canned "light" tuna, which is generally made from smaller fish, is a safer bet. Unfortunately, light tuna also contains fewer omega-3 fatty acids, a component in fish that's thought to be important in a developing baby's brain. Salmon and farm-raised rainbow trout, on the other hand, are both high in omega-3s and relatively low in contaminants.

But because nearly all seafood (and indeed, all food) contains trace levels of contaminants, it's best to vary the types of fish you eat during the course of a week so that you have only one serving of any particular kind, and no more than three servings total. Removing the skin (where many of the contaminants are stored) and cooking fish thoroughly will also reduce some of the harmful chemicals it contains.

Despite these caveats, it's important to note that the benefits of eating fish far outweigh the risks. In addition to omega-3s, fish is an excellent source of other important nutrients, such as protein. So don't swear off seafood — just eat it responsibly.