What Happens If You Eat Tuna More Than Twice a Week, According to Experts

Do you need to mix up your standing lunch order?

When it comes to lunch, nothing is quite as versatile as a can of tuna. Mix it with some mayo to make a tuna salad sandwich, slice up a tomato and some boiled potatoes and eggs for a Nicoise salad, toss it with your favorite pasta and some seasonings, or eat it straight from the tin with some crackers. It would be easy to eat tuna every day and not get bored—but is it safe? If you've heard warnings about mercury and fish, you might be wondering whether to ease up on your tuna consumption.

"I get a lot of questions about this in my medical toxicology practice," says medical toxicologist and Co-Medical Director and Interim Executive Director of the National Capital Poison Center Kelly Johnson-Arbor, MD. Read on to find out what she tells Best Life about how often is too often when it comes to eating tuna—and who is most vulnerable to mercury poisoning, whether it's from fish or another source.

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Eating fish comes with plenty of health benefits.

Person holding a sandwich with tuna fish and sliced avocado on top tomato
Akira Kaelyn / Shutterstock

Adding fish to your diet packs a big nutritional punch. Johnson-Arbor lists improved heart health and a decreased risk of cancer as just a couple of the health benefits of eating fish.

"Many varieties of fish, including tuna, are a healthy food choice and provide many beneficial nutrients, including omega-3 fatty acids, choline, iron, and protein," she says. "These nutrients are necessary for brain development and also support overall health."

She points out, however, that fish may also contain mercury, which is toxic to humans.

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Tuna contains higher levels of mercury than some other types of fish.

Tuna Steaks
Tetiana Chernykova / Shutterstock

"Fish can become contaminated with mercury naturally through the environment, or through industrial processes," Johnson-Arbor explains. "When the mercury enters waterways, it is consumed by fish and bioaccumulates up the food chain. Larger fish, including tuna, swordfish, and shark, are more likely to contain higher levels of mercury than smaller fish."

You may think of mercury as the silver beads in an old-fashioned glass thermometer, but Johnson-Arbor says the mercury in fish is different. "The mercury found in fish is typically methylmercury, an organic form of mercury," she notes. "Methylmercury is a powerful neurotoxin that can cause damage to the developing brains in fetuses, infants, and children."

Because of this, she says, people who are pregnant or trying to become pregnant, breastfeeding parents, infants, and children should limit their consumption of fish that may contain mercury, including tuna.

Most adults don't need to worry about their tuna consumption.

canned tuna salad aphrodisiac foods
HandmadePictures / Shutterstock

Johnson-Arbor has good new for grown-up tuna fans who aren't pregnant or nursing: "Adults who consume tuna or other high-mercury containing fish are unlikely to develop symptoms of mercury poisoning themselves, and the health benefits of fish consumption generally outweigh the risks of methylmercury consumption," she says.

If you're concerned about the mercury content of your fish, it's worth noting that Johnson-Arbor says albacore, or chunk white tuna, has about triple the amount of mercury of chunk light tuna. "The Environmental Protection Agency (EPA) and U.S. Food & Drug Administration (FDA) guidance states that the at-risk populations can consume two to three servings of chunk light tuna a week. For reference, one serving of fish is approximately the size of the palm of your hand."

The bottom line? "Occasional consumption of more than the recommended amount of tuna is unlikely to result in harmful health effects in healthy adults," says Johnson-Arbor.

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Mercury poisoning is a serious concern for babies and children.

Cute young Asian girl eating tuna salad and corn
kornnphoto / Shutterstock

Of course, mercury is still toxic, and presents a serious concern for vulnerable groups of people. "Children, infants, and fetuses who are exposed to high amounts of methylmercury may experience developmental delays, problems with memory and learning, or other signs and symptoms of brain damage," Johnson-Arbor tells Best Life. "These adverse events can occur in children born to mothers who were exposed to methylmercury during pregnancy, even when the mothers are asymptomatic."

If your child has eaten "excessive amounts of tuna or other high mercury containing fish" and you're worried about the possibility of mercury poisoning, she urges you to contact your healthcare provider. "Blood and urine tests can be performed to assess for mercury poisoning," she says. "You or your doctor can contact Poison Control for expert guidance about how these tests should be performed, as well as the interpretation of the test results."

There are two ways to contact Poison Control in the United States: online at www.poison.org or by phone at 1-800-222-1222. Both options are free, confidential, and available 24 hours a day.

Best Life offers the most up-to-date information from top experts, new research, and health agencies, but our content is not meant to be a substitute for professional guidance. If you have specific health questions or concerns, always consult your healthcare provider directly.

Elizabeth Laura Nelson
Elizabeth Laura Nelson is the Deputy Health Editor at Best Life. A mom and a marathon runner, she’s passionate about all aspects of health and wellness. Read more