Can eating the wrong type of fish put you at higher risk for mercury exposure? That’s the question posed in the latest special food safety report published Wednesday from Consumer Reports, the publishing arm of the nonprofit Consumers Union. The noncontroversial answer is yes, certain fish contain higher levels of mercury than others — and different species of tuna can vary significantly in mercury levels. But Consumer Reports has taken the conversation a step further, concluding that pregnant women in particular should completely avoid tuna. That advice directly contradicts that of the Food and Drug Administration, some nutritionists, and, of course, the seafood industry. In June, FDA released guidance recommending that women of childbearing age and young children eat fish as a good source of protein, omega-3 fatty acids and other nutrients. Tuna has long been a top recommendation due to its low price and convenience. Consumer Reports says that canned tuna, the most commonly consumed fish in the U.S., has levels of mercury too dangerous for pregnant women and their developing fetuses. Instead, they recommend 20 seafood alternatives with lower levels of mercury, including salmon and tilapia. For a comparison, a 4-ounce serving of salmon contains about 2 micrograms of mercury. The same amount of canned albacore tuna contains almost 60 micrograms. Swordfish? 150. What about chunk light tuna? While most cans of chunk light contain about one-third to half the amount mercury in albacore, about 20 percent of cans FDA tested contain just as much, said Jean Halloran, director of food policy initiatives at Consumers Union. The problem, Halloran told Food Safety News, is that there are no restrictions on what species of tuna may be put in a chunk light can, and so sometimes higher-mercury varieties are added in. As a result, she said, the maximum levels of mercury seen in both chunk light and albacore tuna are up in the range of fish on the FDA’s do-not-eat list. “If one of those high-mercury cans came at the wrong point in the fetal development, it’s a risk,” Halloran said. “Just like pregnant women are advised not to drink alcohol, during pregnancy it’s prudent to avoid tuna, especially when there are low-mercury seafood alternatives.” Halloran’s favorite alternatives are canned Alaskan salmon and canned sardines, which she jokingly called “highly underrated.” But others think the Consumer Reports message does more harm than good. “When I see reports like this, I just worry that people will be dissuaded from eating a really healthy food,” Colorado State University Nutrition Professor Dr. Mary Harris told Food Safety News. Harris said that scientific literature supports FDA’s recommendation for pregnant women to eat 8-12 ounces of fish per week, or 6 ounces of albacore tuna. The health benefits of eating one to two meals of fish each week far outweigh the mercury risks, she said. “We should look at that 8-12 ounce recommendation as a target, not a limit,” she said. Harris added that she didn’t see salmon or sardines becoming widely adopted as a lower-mercury alternative to tuna because the affordability and ease of preparation with tuna just can’t be beat. In a statement released Wednesday, FDA criticized the report for overestimating the negative effects of mercury in fish and understating the health benefits of eating fish. The National Fisheries Institute, an industry association, responded similarly. “Consumer Reports is dangerously out of touch with science on this matter,” the association said in a statment. “This is not about Consumer Reports and ‘industry’ disagreeing. It is about Consumer Reports promoting its own reckless, hyperbolic, quasi-science and in the process damaging its own credibility.” Halloran at Consumers Union responded that the net-benefit argument made little sense when numerous low-mercury alternatives to tuna exist. “You can get all the same health benefits from lower-mercury fish without taking on the mercury risks with tuna,” she said. “We all agree that women and children should eat low-mercury fish.” FDA includes a list of fish species with their average levels of mercury on its information page entitled, “Fish: What Pregnant Women and Parents Should Know.” Both FDA and Consumer Reports agree that pregnant women and children should never eat the following four fish that contain the highest mercury levels:

  • Swordfish
  • Shark
  • King mackerel
  • Gulf tilefish

Consumer Reports adds two more fish to their do-not-eat recommendation:

  • Marlin
  • Orange roughy

Consumer Reports additionally advises any adults who eat more than 24 ounces of fish each week to avoid high-mercury choices.