Face-Off: Is It Safe to Eat Canned Tuna During Pregnancy?

Our experts face off. Chime in with your own comments.

YES, says obstetrician-gynecologist Karen Filkins, M.D., a fellow of the American College of Medical Geneticists and member of the Teratology Society.

Canned tuna is a higher-risk fish, but it's safe to eat as long as it is not your main source of food and is consumed in limited quantities. The risk of mercury is cumulative, so an occasional serving of tuna is not going to harm your baby.

Fish is a very important part of a pregnant woman's diet--it's full of protein, omega-3 fatty acids and other nutrients that have a protective value for the fetus and may actually counterbalance the effects of mercury and other contaminants in the environment. That said, to minimize your risk, limit intake of canned tuna and other large predatory fish to 6 to 12 ounces a week; choose smaller fish the rest of the time. (All large predatory fish, such as shark and swordfish, have a higher risk of being contaminated with mercury.)

Also make sure your fish comes from safe waters. The government regulates the commercial fishing industry, so fish sold through supermarkets and restaurants is usually safe. If you want to eat fish that was not caught commercially, check with your local branch of the Environmental Protection Agency or Health Department to be sure the water it was taken from is safe.

Finally, keep in mind that this whole issue relates to risks versus benefits: When do we call something safe or not safe? Nothing is totally safe--even the air we breathe can be unsafe at times. We can be afraid of so many things in our environment, but we always have to weigh the risks and benefits.

NO, says Jean Halloran, director of food policy initiatives at Consumers Union in Yonkers, N.Y.

We think pregnant women should avoid canned tuna. The problem is that different cans have different levels of mercury--some have up to seven times as much as the average can. If there weren't such a variance, we could come up with an acceptable intake during pregnancy--such as 12 ounces of chunk-light per week, as some experts recommend.

On average, chunk-light tuna has one-third as much mercury (0.12 parts per million) as solid-white albacore (0.35 parts per million), so it is typically considered safer. But as we reported in the July 2006 issue of Consumer Reports, U.S. Food and Drug Administration data show occasional levels of about 0.85 parts per million in both chunk-light and solid-white albacore. At that level, we're concerned about the safety of the fetus--significant problems could arise if you were to have a sudden high dose of mercury at a time when the brain or nervous system is developing.

We don't want to be alarmist, and it's not the end of the world if you eat one can of tuna. But we do want women to give their babies the best possible start, and since we don't know which cans are going to contain those 0.85 parts per million of mercury, we think it's better to avoid this fish altogether. Pregnant women should also avoid shark, swordfish, king mackerel and tilefish, as they're also frequently very high in mercury. For healthy alternatives, try wild salmon (farm-raised varieties can contain high levels of PCBs), shrimp, tilapia and clams.