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.
The high levels of omega-3 fatty acids in tuna fish may help to reduce the level of omega-6 fatty acids and LDL cholesterol that can accumulate inside the arteries of the heart. Studies have shown that eating more omega-3 is associated with reduced rates of cardiovascular disease, including heart attacks.
Is canned tuna safe to eat regularly? Yes. In general, it is safe for all population groups, including pregnant women, to consume 2-3 serves of any type of tuna per week (canned or fresh).
Yellowfin and albacore tuna land somewhere in between, containing around 30 micrograms of mercury per 3 ounces. Given these mercury concentrations, people may safely consume three to four servings of low-mercury tuna per week.
Canned light tuna contains the least amount of mercury, and the FDA suggests limiting yourself to no more than 12 ounces a week, or no more than four 3-ounce cans.
Health effects of mercury exposure
The inhalation of mercury vapour can produce harmful effects on the nervous, digestive and immune systems, lungs and kidneys, and may be fatal. The inorganic salts of mercury are corrosive to the skin, eyes and gastrointestinal tract, and may induce kidney toxicity if ingested.
There's no cure for mercury poisoning. The best way to treat mercury poisoning is to limit your exposure to the metal. If you eat a lot of mercury-containing seafood, a doctor may caution you to stop immediately.
Blood mercury levels above 100 ng/mL have been reported to be associated with clear signs of mercury poisoning in some individuals (e.g., poor muscle coordination, tingling and numbness in fingers and toes).
Canned light tuna is the better, lower-mercury choice, according to the FDA and EPA. Canned white and yellowfin tuna are higher in mercury, but still okay to eat. Bigeye tuna should be avoided completely, but that species isn't used for canned tuna anyway.
Interestingly, although tuna is a large predatory fish it generally has mercury levels <0.5 mg/kg.
If you're a 180-pound guy eating light tuna, you could safely eat 9.5 five-ounce cans according to the CDC, or 3.2 five-ounce cans according to the EPA.
Tuna not only improves the metabolic rate in individuals but also increases bodily functions to keep you energetic, active, and healthy. For example, eating tuna after a workout will help you to maintain your energy while reducing belly fat due to the high-thermic effect. This fish is a complete protein.
While the tuna diet offers rapid weight loss, it's not a sustainable, long-term solution. In fact, it poses several risks, including slowed metabolism, loss of muscle mass, and mercury poisoning. For lasting results, the best option is to follow a balanced meal plan with sufficient calories to meet your needs.
There are a few things that your body could be lacking if you crave fish, such as tuna. One of the most common reasons is that you may be lacking in fat and protein. And one common reason you might need more fat and protein than normal is pregnancy! Your body needs these nutrients in order to function properly.
The traditional treatment for mercury poisoning is to stop all exposures. In many cases, chelation therapy is also used. This involves giving a medication (the chelator) which goes into the body and grabs the metal (chelos is the Greek word for claw) then carries the metal out of the body, usually into the urine.
Most of the metallic mercury will accumulate in your kidneys, but some metallic mercury can also accumulate in the brain. Most of the metallic mercury absorbed into the body eventually leaves in the urine and feces, while smaller amounts leave the body in the exhaled breath.
If inorganic mercury enters your bloodstream, it can attack the kidneys and brain. Permanent kidney damage and kidney failure may occur. A large amount in the bloodstream may cause massive blood and fluid loss from diarrhea and kidney failure, leading to death.
The average mercury levels in the FDA data we analyzed indicated that a 125-pound woman would exceed the EPA's "safe" consumption limit for mercury by eating just 4 ounces of albacore tuna per week. A 48-pound child would exceed the limit eating any more than 1.5 ounces (about a third of a can).
Once in the body mercury has a half-life of ~3 days in the blood stream and a 90 day half life in other tissues (e.g. brain, kidneys, etc).
Poisoning from methylmercury can take weeks or months to appear. A chemical spill with elemental mercury or inorganic mercury might give you symptoms more rapidly. Mercury poisoning is diagnosed by testing your blood and urine for mercury levels.
These recommendations are based on EPA guidance and estimates of mercury in the most popular canned tunas: Canned white, or albacore (0.32 parts per million of mercury). Children under six can eat up to one 3-ounce portion a month; children from 6-12, two 4.5-ounce portions a month.
Mercury and its compounds affect the central nervous system, kidneys, and liver and can disturb immune processes; cause tremors, impaired vision and hearing, paralysis, insomnia and emotional instability.
The Dietary Guidelines for Americans states that to consume those higher amounts, children should only be fed fish from the “Best Choices” list that are even lower in mercury – these fish are anchovies, Atlantic mackerel, catfish, clams, crab, crawfish, flounder, haddock, mullet, oysters, plaice, pollock, salmon, ...