New research from Consumer Reports shows that pregnant women should avoid all tuna, contrary to the Food and Drug Administration's description of light canned tuna as a fish "lower in mercury."
"Tuna happens to be one of the fish that can be very high in mercury, and some types of tuna have higher levels than others," Jean Halloran, Director of Food Policy Initiative at Consumer Reports told The Huffington Post. "The type that tends to get used in sushi is often very high, but even canned light tuna, which tends to average pretty low levels and is generally one of the safer fish to eat, occasionally has these spikes of high levels of mercury."
Because pregnant woman can't tell which individual cans may have higher levels of tuna, Consumer Reports recommends that pregnant women simply skip all tuna throughout their entire pregnancy.
The findings were published online Thursday on online and will appear in the Oct. 2014 issue of the nonprofit's magazine, Consumer Reports.
The FDA's advice on light canned tuna is from 2004, and the federal agency is poised to overhaul all its advice on seafood consumption soon, reports the Wall Street Journal. But a draft of the new recommendations, subject to final approval, still lists light canned tuna as a low-mercury fish for vulnerable groups.
Seafood contains nutrients like protein, iron and omega-3 fatty acids, which are especially vital for the growth and brain development of fetuses, breastfeeding babies and young children. But certain kinds of seafood, especially larger fish, can contain a neurotoxin called methylmercury (commonly referred to as simply "mercury") that can cause severe birth defects like blindness, deafness and mental retardation if fetuses are exposed to the metal in utero.
Canned tuna was once the most widely-consumed type of seafood in the U.S., and in 2012 still came in second, after shrimp. Despite the rankings, all canned seafood, of which tuna is the leader, dropped to its lowest level in more than 15 years, reports the Washington Post -- perhaps because of health concerns like mercury.
Currently, the FDA recommends that pregnant women, women who may become pregnant, nursing mothers and young children also stay away from shark, swordfish, king mackarel and tilefish -- recommendations that Consumer Reports agrees with. But when it comes to the FDA's recommendations of which seafood those groups should eat, the government agency stops short of a comprehensive list, save these suggestions: salmon, shrimp, pollock, tilapia, catfish, cod and light canned tuna, about two to three times a week.
To give people a wider selection of low-mercury seafood, CR took the Environmental Protection Agency's data on the average amount of mercury per fish and listed them into two groups: "Lowest" mercury and "Lower" mercury as part of their report.
"The best fish on the list is salmon," said Halloran. "Virtually all the canned salmon in stores is wild Alaskan salmon, and it's a very good substitute for canned tuna -- it's just a little more work, because you have to take the bones out."
To see Consumer Report's list of the 17 best seafoods with low mercury levels, check out the slideshow below.