If you're concerned about limiting the amount of mercury you consume, and if you've eaten no other fish during the week, Consumer Reports says up to 12 ounces a week of Bumble Bee Chunk Light,
Safe Catch Elite Tuna, simply the lowest mercury tuna of any brand.
Canned light tuna is low in mercury and is considered one of the best choices for individuals that need to limit their exposure to mercury. People who are pregnant or breastfeeding can consume 2–3 servings of canned light tuna per week and children can consume 2 servings 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.
Best in breed
Think twice about yellowfin, which is generally less sustainable than skipjack. If the tin doesn't list the type of tuna, don't buy it. Brands with decent credentials include Fish 4 Eva, John West, Safcol and Sirena. Aldi and Coles own-brand cans are OK, too, but check each for breed and catch method.
It's generally safe for all population groups, including pregnant women, to consume 2-3 serves of any type of tuna or salmon a week, canned or fresh. Canned tuna usually has lower mercury levels than other tuna because tuna used for canning are smaller species that are caught when less than 1 year old.
If a can is at all dented, rusting, or bulging, it should be thrown away immediately, as this is likely to have caused a rupture. Even if you can't see an issue with the can, if there appears to be some leaking, the canned product is probably no longer safe to eat.
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. Adults, including pregnant women, can safely eat this kind of tuna up to three times a month (women, 6-ounce portions; men, 8-ounce portions).
"While canned tuna, especially light varieties, has relatively low average levels of mercury, individual cans can sometimes have much higher levels," Consumer Reports said.
Five of the most commonly eaten fish that are low in mercury are shrimp, canned light tuna, salmon, pollock, and catfish. Another commonly eaten fish, albacore ("white") tuna, has more mercury than canned light tuna.
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.
Salmon is low in mercury.
Both wild and farmed Atlantic salmon have much lower mercury levels than most other fish species. Farmed salmon has on average, 0.05 micrograms of mercury per gram.
SAFCOL TUNA
The South Australian Fishermans Co-Operative Limited (S.A.F.C.O.L.)
Sirena is an Australian brand of canned premium chunk style tuna which began as a passion for good food and a desire to share great tasting food with the community. After immigrating to Australia in 1949, Carlo Valmorbida and his family embarked on a project to bring Italy's best loved foods to Australia.
If you're counting calories and maximizing omega-3 fatty acids, then tuna in water might make a great choice. On the other hand, if moisture, flavor, and vitamin D levels are your focus, then olive oil-packed tuna might be better. Whatever tuna you choose, it's important not to go overboard for this mild-flavored fish.
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. Before consuming canned tuna, it is best to consult with your doctor if you have any questions or concerns.
One big takeaway is that albacore has much more mercury than light or skipjack tuna, regardless of the brand. That's not surprising, since albacore is larger and lives longer than the tunas that make up the light tuna or skipjack tunas.
They recommend that people who are not pregnant eat no more than one to two cans of albacore per week, depending on brand, but that up to three cans per week of most brands of chunk light tuna are fine. Chicken of the Sea, Safe Catch, and Starkist brands showed lower levels of mercury in their tests.
But scientists say more tests are needed to confirm that. Cooking does not remove mercury from fish because the metal is bound to the meat. For example, a piece of tuna will have the same amount of mercury whether it is eaten raw as sushi or cooked on the grill.
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).
Sardines are small and contain a lot of oil. They are also a low-mercury fish, so it's safe to eat them if you are pregnant or breastfeeding.
Instead of signaling spoilage, though, those dark centers in a tuna filet are caused by the presence of myoglobin (via MyRecipes). According to zoologist Bruce Collett, in a conversation with KUOW, myoglobin is responsible for helping muscles store oxygen, which strong-swimming fish like tuna need in abundance.