Report deems canned tuna 'too risky' in pregnancy. Here's what an OB-GYN says

A spot check of canned tuna shows there can be unpredictable spikes in mercury levels from one can to another, making the staple “too risky” to eat during pregnancy, Consumer Reports warns in a new analysis published on Thursday.

But a doctor who helped write the pregnancy guide from the American College of Obstetricians and Gynecologists says the findings don’t change the current recommendations for how much tuna pregnant women can eat. Six ounces or less per week are safe for them to consume, according to the ACOG guide.

And the fish industry says the mercury levels found by Consumer Reports are far below the limit set by the U.S. Food and Drug Administration.

The concern is that this level may not be health protective, says James Rogers, director of food safety research and testing at Consumer Reports.

“We believe the lowest amount of mercury that you can get in these products (is) better for consumers,” Rogers tells TODAY.com.

What does mercury do to the human body?

Eating seafood is the most common way Americans are exposed to mercury, a heavy metal and powerful neurotoxin, though most types of fish don’t have levels high enough to be toxic, the FDA notes.

But big predatory fish like tuna can contain especially high concentrations of mercury in their bodies, according to the Natural Resources Defense Council, an environmental advocacy group.

Eating too much seafood that’s high in mercury over long periods of time can lead to mercury poisoning. Symptoms include skin numbness, shakes and tremors, double vision, memory problems and seizures, according to the National Library of Medicine.

Being exposed to large amounts of mercury while pregnant may cause permanent brain damage in the baby, the National Institutes of Health notes.

That's why the FDA offers a guide to fish that are highest and lowest in the contaminant. Canned light tuna is listed among "best choices," which means two to three 4-ounce servings per week are safe to eat during pregnancy, according to the agency.

Albacore tuna is listed among "good choices," which means one 4-ounce serving per week is safe to eat during pregnancy.

What the Consumer Reports analysis found:

Consumer Reports looked for mercury in samples of canned tuna packed in water from Bumble Bee, Chicken of the Sea, StarKist, Safe Catch and Wild Planet. Two varieties of the fish from each of the five brands were tested: albacore, which comes from larger tunas; and light tuna, which comes from smaller species such as skipjack.

With three samples of each product from different lots, 30 samples were tested in all.

Consumer Reports says it found “six individual spikes in mercury content that would change the FDA’s recommendation about how often someone should eat that particular tuna.” Those spikes happen because tuna is a wild-caught fish, so humans don’t control their feed, Rogers says. They may eat more or less of other mercury-contaminated fish.

In their sample they found albacore tuna, also known as white tuna, has much more mercury regardless of the brand. Albacore typically contains three times more mercury than canned light tuna, according to the FDA.

Mercury levels can spike in unpredictable ways that might jeopardize the health of a fetus, Rogers says. “The variation we see from can to can makes tuna too risky for pregnant people” adds Michael Hansen, a senior scientist at Consumer Reports.

The organization’s advice is to avoid canned tuna altogether if you are pregnant. It also recommends children should eat light or skipjack tuna only.

Industry responds

The National Fisheries Institute, which represents canned tuna manufacturers, says the mercury levels Consumer Reports found were “nowhere near” the amount the FDA links with health problems.

The FDA’s limit for mercury in fish is 1 part per million, which is ten times lower than the lowest levels associated with adverse effects, says Gavin Gibbons, a spokesperson for the institute.

The highest levels of mercury Consumer Reports found in cans of light tuna and albacore were 0.58 and 0.66 parts per million, respectively, he points out.

“Neither of these levels begin to even approach this limit and are completely safe to consume,” Gibbons says in a statement to TODAY.com.

The National Fisheries Institute has also posted an online response to the Consumer Reports analysis.

TODAY.com reached out for comment from the five companies whose tunas were tested.

Safe Catch says it has invented an analyzer to screen tuna for mercury and has tested more than 6 million of the fish. It's "the only brand that tests each individual tuna to a strict mercury limit before we purchase it," CEO and co-founder Bryan Boches notes in a statement.

Wild Planet says it has an ongoing annual surveillance program that includes mercury. The company's findings show its skipjack averages mercury levels 14 times lower than the FDA limit, while its albacore averages mercury levels six times lower, according to president and founder Bill Carvalho.

The other companies did not respond. But StarKist and Chicken of the Sea told Consumer Reports that their tuna products are monitored for mercury and meet the FDA limit.

Bumble Bee told the organization that the “health benefits of consuming seafood far outweigh any potential risk, including concerns about mercury.”

What an OB-GYN says

Dr. Manijeh Kamyar, a maternal-fetal medicine specialist and OB-GYN in Las Vegas, Nevada, says the Consumer Reports analysis wouldn’t change the recommendation she gives her pregnant patients: One 6-ounce serving of tuna per week is safe to eat.

Kamyar helped write “Your Pregnancy and Childbirth,” a guide from the American College of Obstetricians and Gynecologists, which also advises the 6-ounce limit and specifically references albacore tuna.

“I don’t agree with the blanket statement of: Avoid canned tuna in pregnancy. I think if you follow the guidelines for how much we recommend, you’ll still be falling well within a normal level of mercury during pregnancy,” Kamyar tells TODAY. com.

“I understand that there are variations between the cans of tuna, but we’re not recommending large quantities specifically of tuna in pregnancy anyway… the amount of mercury that would lead to birth defects would not be what’s found in one can of tuna, even with those varying levels.”

Patients ask her all the time about eating tuna, she notes. If one were to tell her they love canned tuna and plan to eat it every day during pregnancy, Kamyar would point them to the Consumer Reports analysis.

Otherwise, the report doesn’t add anything different, the doctor says.

This article was originally published on TODAY.com