What happens if you eat too much tuna

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Eating Canned Tuna
Eating Too Much Tuna
Canned tuna contains mercury, so eating too much of it can lead to mercury poisoning.
How it's possible to get high levels of methylmercury in the body.
How to stay safe.
More content from Healthy Eating
How many cans of tuna a day is too much?
What would happen if I ate tuna everyday?
How much tuna is safe per week?

Danger in Eating Too Much Canned Tuna

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Canned tuna is preserved tuna with a shelf life that can last several years. You probably take your canned tuna for granted, but it's only really been around since the 1900s. Before that, if you wanted a tuna salad or sandwich, you needed to find yourself a fresh or salted fish. Because of its convenience, low cost and nutritional benefits, canned tuna can be an easy food to incorporate into takeaway lunches or other meals. However, there is such a thing as too much tuna. Canned tuna may contain heavy metals and other elements, which means that this is not a food you should be eating every day. Certain people may want to avoid it entirely.

Eating Canned Tuna

At the supermarket, you'll often find a wide variety of canned tuna available. These products come from different types of tuna, as well as different countries. Some of the most popular types of canned tuna include albacore, bigeye, bluefin, skipjack and yellowfin tuna.

In general, tuna is thought of as a healthy, tasty food to eat. Canned tuna has high amounts of omega-3 fatty acids, protein, selenium and vitamin D. However, this type of fish is well known for containing mercury, heavy metals and other elements that, in excess, can be detrimental to your health.

It's still true, though, that canned tuna actually has lower levels of mercury compared to fresh tuna. This means that you can safely eat canned tuna more frequently than fresh. The amount of tuna that's recommended depends on the type of tuna you choose to consume.

Eating Too Much Tuna

Fish are well-known for being an important source of vitamins and minerals, especially omega-3 fatty acids. However, fish are also known for their mercury content, and among the many different types of tuna, mercury content varies. The types known for mercury content include ahi, albacore and bigeye.

If you're a tuna connoisseur, you know that ahi and bigeye tuna are frequently used raw, in sushi, while albacore is one of the primary types of tuna used in canned varieties. Albacore, otherwise known as canned white tuna, has about 0.32 parts per million of mercury. There's also a second type of canned tuna, though — canned light tuna made from skipjack tuna. Canned light tuna only has 0.12 parts per million of mercury.

Mercury isn't something you should consume too often; it can be a neurotoxin. For that reason, adults should eat limited amounts of tuna. With albacore tuna, women should eat three 6-ounce portions of tuna per month, while men can have three 8-ounce portions. Children must have less — between two 4.5-ounce portions and one 3-ounce portion per month, depending on age.

You can safely eat more canned light tuna than albacore. Adults and children over six can eat this type of tuna once a week without issue. If you eat more than the recommended amount, you could get mercury poisoning. High levels of mercury in tuna can have side effects.

Symptoms of mercury poisoning include loss of coordination, memory problems, numbness, pain, problems with vision, seizures and tremors. Mercury poisoning can also cause problems with the development of your baby if you're pregnant.

Mercury is the element in fish with the worst reputation, but other toxins come into play, often due to contaminated water — and they can affect our health, too. These contaminants include arsenic, cadmium and lead.

The good news is that these heavy metals rarely reach levels that should concern you, as long as you're eating the recommended amounts of tuna. The bad news is that these contaminants are found worldwide — from Brazil to Ghana to Iran. The bottom line is that, while tuna fish is healthy and delicious, there are no benefits to eating it every day. Excessive consumption of tuna, even canned tuna, is bad for your long-term health.

Know your fish so you don't get chicken-of-the-sea sick.

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For many of us, our pantries are stocked to the gills with canned tuna. It's both inexpensive and a good source of belly-filling protein. Plus, it requires no cooking, not even a plate—just a can opener and two slices of bread. Bingo! You have lunch, a snack, or dinner!

Since it's such a convenient source of protein, you may find that you eat a lot of tuna now—three, four, five times a week, maybe? Depending on how much and, especially what kind of canned tuna you're eating, you may be getting too much, potentially resulting in a fishy side effect called mercury poisoning. But before you dis fish, read on, and check out these 6 Ways Eating Fish Can Help You Lose Weight.

Canned tuna contains mercury, so eating too much of it can lead to mercury poisoning.

Consumption of ocean fish and shellfish accounts for more than 90% of human exposure to mercury in the United States, and tuna harvested in the Pacific Ocean accounts for 40% of this total exposure, according to a study in Environmental Health Perspectives.

Mercury in the air from coal-fired electricity generation and other human industrial activities settles in lakes, rivers, and oceans where it is consumed by marine life. But mercury in oceans is also a product of nature's organic carbon decomposition, according to scientists reporting in the journal Global Biological Cycles. When mercury enters the water, either way, microorganisms transform it into a highly toxic form called methylmercury that builds up in the flesh of fish that we eat. Methylmercury bioaccumulates in larger predators, which is why bigger fish like tuna are riskier to eat than, say, sardines. (Related: The #1 Best Fish to Eat, According to a Dietitian.)

How it's possible to get high levels of methylmercury in the body.

"All fish have some level of mercury, but that level varies widely; canned tuna has relatively high levels of mercury so its consumption could potentially become harmful above three or so servings a week," says Andrea Paul, MD, medical advisor to Illuminate Labs.

Nearly everyone has a small amount of methylmercury in their blood that's below levels that may trigger health effects, according to U.S. Centers for Disease Control and Prevention (CDC) data. But methylmercury is a powerful neurotoxin, so eating too much fish may result in mercury poisoning. Symptoms include itching or a pins-and-needles feeling in the toes and fingertips, muscle weakness, coordination, speech and hearing impairment, and reduced peripheral vision. High mercury levels in women who are pregnant may result in central nervous system disorders in their babies.

How to stay safe.

The Food & Drug Administration and Environmental Protection Agency recommend that women and children (over age 10) eat two to three servings (8 to 12 ounces) of a variety of fish and shellfish each week because seafood is a great source of omega-3 fatty acids, which are essential to healthy brain development. Both agencies recommend choosing low-mercury seafood and have created an advice chart showing how often to eat 60 different types of fish by designating them as either "best choices" (eat 2 to 3 times weekly), "good choices" (eat 1 serving per week) or "choices to avoid" (highlighting fish containing the highest levels of mercury).

The popular canned white (albacore) tuna makes the one 4-ounce-serving-per-week list because it's a larger fish that contains higher amounts of mercury than the fish on the "best choices" list. Canned "light" tuna (mostly skipjack tuna) earns a spot on the "best choices" list because it's a smaller fish that typically is lower in mercury.

But an environmental health advocacy organization called the Environmental Working Group says the government's guidelines may put women at risk. In a nationwide study, EWG recruited 254 women of childbearing age from around the nation who reported eating as much or more fish as government suggestions. Researchers tested samples of their hair because mercury accumulates there and reflects the mercury level in the body. Nearly 30% of the women studied had over the EPA's safe limit of mercury and almost 60% had more mercury than a stricter limit set by two European institutions. The EWG believes including canned light tuna on the "best choices" "lower-in-mercury" category is wrong since skipjack "is a significant source of mercury in women's diets," it says. Based on a food questionnaire, tuna contributed almost 40% of the mercury ingested by participants in the Mercury Policy Project study, the EWG says.

If you want to cut back on canned tuna, try salmon, a low-mercury fish on the FDA's "best choices" list. And here's a delicious recipe for a salmon fish taco bowl. Enjoy!

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How many cans of tuna a day is too much?

Recommendations for healthy tuna consumption can vary greatly. Some sources say eating more than a serving of tuna each week may put you at risk. However, other sources say that you would need to eat at least three cans of tuna a day for 6 months to risk mercury toxicity.

What would happen if I ate tuna everyday?

The Bottom Line. Mercury exposure is linked to health issues including poor brain function, anxiety, depression, heart disease and impaired infant development. Though tuna is very nutritious, it's also high in mercury compared to most other fish. Therefore, it should be eaten in moderation — not every day.

How much tuna is safe per week?

You would have to eat around 25 tins (at 95g a tin) of it a week before you hit the maximum tolerable intake of mercury. For pregnant people (or people trying to get pregnant), the limit would be around 12 tins (at 95g a tin) a week.