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). Canned tuna generally has lower levels of mercury than other tuna because the tuna used for canning are smaller species that are generally caught when less than 1 year old.
Canned light tuna is in the “Best Choices” category and it is fine to eat 2 to 3 servings per week. We recommend that you eat a variety of fish. You may wish to try other affordable fish in the “Best Choices” category such as canned salmon or sardines, frozen fish, or fresh fish that are at a reduced price.
Canned light, the safer choice (0.12 parts per million of mercury). Children under six can eat up to three 3-ounce portions per month. Older children and adults can safely eat it once a week.
Tuna: if you are trying for a baby or are pregnant, you should have no more than 4 cans of tuna a week or no more than 2 tuna steaks a week. This is because tuna contains higher levels of mercury than other fish. If you are breastfeeding, there is no limit on how much tuna you can eat.
"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.
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). Canned tuna generally has lower levels of mercury than other tuna because the tuna used for canning are smaller species that are generally caught when less than 1 year old.
Eating more than the advised amount of tuna each week can result in increased exposure to the neurotoxin. Mercury poisoning can cause several concerning neurological symptoms, including coordination loss, memory problems, seizures, and tremors.
The benefits of eating canned tuna every day outweigh the risks. Because canned tuna provides omega-3 fatty acids and is a lean source of protein, there's no harm in adding it to your daily diet. "Mercury levels are very low, and canned tuna is the most economical and accessible way to consume omega-3s," Miller says.
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.
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 three 5-ounce cans.
The FDA recommends consuming fish lower in mercury. For tuna varieties, skipjack earns the Best Choice label from the FDA, while yellowfin and albacore receive the Good Choice label. The FDA suggests avoiding bigeye tuna, which has the highest levels of mercury.
Summary. Fish that contain high levels of mercury include shark, ray, swordfish, barramundi, gemfish, orange roughy, ling and southern bluefin tuna. Mercury is a naturally occurring element that is found in air, water and food.
Canned Tuna or Salmon
Will stay fresh after opening for 1 to 2 days in the refrigerator. Transfer opened canned fish to a sealed glass container or plastic bag.
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).
Elemental mercury, if inhaled, can cause permanent lung damage and potential brain damage. Inorganic mercury can damage kidneys and cause blood loss. Organic mercury can damage your central nervous system (brain and spinal cord). Large amounts of mercury or long-term exposure can lead to death if not treated.
Too much sodium can lead to high blood pressure, stroke, and heart disease —but “in the context of a varied diet, [tinned fish] likely won't make too much of a difference,” Rumsey says. Basically, if you don't eat it every day, at every meal, you're probably good.
Fish that are very high in mercury include bigeye tuna (a kind sometimes used in sushi), king mackerel, orange roughy, shark, and swordfish. These should be consumed only very occasionally, if at all, and not ever by children or people who are or could become pregnant.
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.
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).
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. The United States Food and Drug Administration recommends keeping the consumption of albacore (white) tuna to under 4 ounces per week and skipjack (light) tuna to under 12 ounces per week.
Skipjack are the smallest of the major tuna species, while yellowfin are larger. So, the fact the canned tuna in Australian cupboards is likely to contain smaller species is already a bonus when it comes to reducing mercury risk.