Tuna, especially canned, is cheap and easy to find, so a new Consumer Reports warning may pose an extra challenge for pregnant women looking to add more fish to their diet.
Fish provides important nutrients for fetal brain development, and pregnant women aren't consuming enough, according to a joint statement issued this summer by the Food and Drug Administration and the Environmental Protection Agency. The agencies recommended that pregnant women eat between 8 and 12 ounces of fish a week.
They cautioned, however, against eating fish high in mercury such as tilefish from the Gulf of Mexico, shark, swordfish and king mackerel. They gave the green light to canned light tuna and suggested up to 6 ounces of white (albacore) tuna a week.
Consumer Reports disagrees. The magazine recommends that pregnant women avoid tuna. Its food-safety experts analyzed the FDA's own data that measures mercury levels in various types of seafood and concluded that tuna was not a safe choice for pregnant women.
"When you have an excessive mercury intake, it concentrates within the developing brain of the fetus," says Brandon L. Reynolds, DO, an adjunct professor in the University of Utah Department of Obstetrics and Gynecology. "When that happens, it can interrupt important connections necessary for brain development, which can lead to mental or neurological problems."
Consumer Reports says canned tuna accounts for 28 percent of Americans' exposure to mercury. In the U.S., it's second only to shrimp as the most commonly eaten seafood.
Since it's impossible to test every single fish, this can be frustrating for pregnant women trying to get enough of the beneficial fatty acids fish contain and also avoid mercury, Reynolds says. Pregnant women should still eat low-mercury seafood like shrimp, he adds.
"This just really illustrates how varied it can be when you do specific testing on fish from different sources," he says. "It just muddies the waters."