The safest canned tuna for most people is the cheap, everyday kind labeled light or chunk light. What separates a low-mercury can from a high-mercury one is mostly which fish is inside, not the brand on the label. And for nearly everyone, including pregnant women, the goal is choosing well rather than giving tuna up, because fish carries real benefits.
Light Tuna Has Far Less Mercury Than White Albacore
In US canned tuna, white tuna averaged about 0.41 parts per million (ppm) of mercury, and light tuna about 0.12.1PubMed. Mercury in canned tuna: white versus light and temporal variation Another check found light tuna packed in water averaged about 0.05 ppm, among the lowest of any tuna product.2Journal of Food Science. Mercury and Fatty Acids in Canned Tuna, Salmon, and Mackerel Even so, all canned tuna in that check stayed below the FDA’s legal action level of 1 ppm.3Journal of Food Science. Mercury and Fatty Acids in Canned Tuna, Salmon, and Mackerel
Light tuna is usually a mix of smaller species, most often skipjack, a small, short-lived tuna.4U.S. Food and Drug Administration. Questions & Answers from the FDA/EPA Advice on Eating Fish White tuna is albacore, a larger species. Light cans can also contain yellowfin; in some testing skipjack and yellowfin ran close to each other, while albacore was highest of all.5PubMed Central. Variability of Mercury Concentrations Across Species, Brand, and Tissue Type in Processed Commercial Seafood Products In Pacific tuna products, skipjack tended to be lower than bigeye and yellowfin.6PubMed Central. Low mercury, cadmium and lead concentrations in tuna products from the eastern Pacific So the light-versus-white split is the reliable rule, and the differences inside light tuna are small.
On the shelf, labels like chunk light, light, and skipjack all point to the lower-mercury group. Solid white and albacore labels point to the higher one. A premium price doesn’t buy lower mercury. Yellowfin or ahi cans sit in between and vary by catch.
Someone who swaps a weekly white can for a light one cuts the mercury from that meal by about two thirds. If you eat a can only now and then, either type fits within federal advice.
Keep in mind that 0.12 and 0.41 are averages across many cans, so any single can may land above or below them. A light can runs higher when the mix includes more yellowfin, which is why the label rule is a strong guide but not a promise. Even a higher-than-average light can usually sits well under the level where regulators act, so one unlucky can is no cause for alarm.
Why Bigger, Older Tuna Carry More Mercury
Nearly all mercury in canned tuna, at least 89%, is a form the body absorbs and that affects the nervous system.7PubMed. Mercury in canned tuna: white versus light and temporal variation In tunas, mercury rises steadily as body size grows.8PubMed. Trophic influences on mercury accumulation in top pelagic predators from offshore New England waters of the northwest Atlantic Ocean Heavier yellowfin tuna, for example, carried clearly more mercury than lighter ones.9PubMed. Mercury accumulation in Yellowfin tuna (Thunnus albacares) with regards to muscle type, muscle position and fish size Albacore is larger and lives longer than the fish usually used in light tuna, which explains much of the gap.10U.S. Food and Drug Administration. Questions & Answers from the FDA/EPA Advice on Eating Fish
The path from ocean to can starts with mercury from pollution and natural sources settling into the sea. Tiny organisms convert it to the absorbable form, which passes up through prey to the fish that eat them.
Mercury also rises sharply the higher a fish feeds in the food chain.11PubMed. Trophic influences on mercury accumulation in top pelagic predators from offshore New England waters of the northwest Atlantic Ocean Skipjack feeds lower, stays nearer the surface, and lives a shorter life, so it stays relatively low.12PubMed Central. Evidence that Pacific tuna mercury levels are driven by marine methylmercury production and anthropogenic inputs Skipjack mature quickly and live only a few years, while albacore live considerably longer.
Where a tuna is caught matters too, with yellowfin averages varying up to eightfold between ocean areas.13PubMed Central. Mercury levels of yellowfin tuna (Thunnus albacares) are associated with capture location But cans rarely list catch location, so species remains the practical guide.
Cooking or draining won’t help. Mercury binds to the muscle protein of the fish, so draining the liquid or heating the tuna doesn’t remove it. Only choosing lower-mercury fish and smaller portions lowers your intake.
How to Read a Tuna Can Label
In the US, the word white on a tuna can may only be used for albacore.14eCFR. 21 CFR 161.190 — Canned tuna Light, on the other hand, can cover any of about 14 tuna species that are pale enough in color.15eCFR. 21 CFR 161.190 — Canned tuna So white tells you the species exactly, while light only tells you it isn’t albacore. A can that names skipjack on the front or in the ingredients is the most certain low-mercury pick.
Tonno, ahi, and yellowfin labels mean a mid-mercury species.
Packing liquid changes fat and calories, not mercury. In one large check, water- and oil-packed cans had nearly the same mercury. Pick by taste and calories, then by species.
Sodium is worth a glance too. Canned tuna carries added salt, which processing raises, and low-sodium or no-salt-added versions help people watching their blood pressure.
Do Brands Matter for Mercury
Brands do differ, though less than you might hope. In one market survey abroad, only two of six brands were consistently low enough to pose little mercury risk.16PubMed. Mercury in canned tuna marketed in Cartagena, Colombia, and estimation of human exposure Independent product testing found high mercury in some albacore brands and moderate levels in others and in light tuna.17ConsumerLab.com. Tuna, Salmon, Sardines & Mackerel Reviews & Top Picks Even within one type, cans vary, so species matters more than any single brand.
If you prefer white tuna, size is the lever. Albacore caught by pole-and-line or troll averages about 12 to 20 pounds, far smaller than the 80-pound maximum.18Seafood Watch. Troll and pole-and-line albacore tuna These younger fish carry about a third of the mercury of longline-caught albacore.19Seafood Watch. Troll and pole-and-line albacore tuna So troll- or pole-caught labels are the lower-mercury choice in white tuna. Some brands test each batch and publish the results, which offers more certainty.
A well-known brand sells many products, including both light and white, so the name doesn’t say which one is in your hand. Brands also source fish from different fleets and seasons, so the same label can change between batches.
How Much Canned Tuna Is Safe to Eat
US agencies set fish limits from a safe daily mercury dose of 0.1 micrograms per kilogram of body weight.20US EPA. EPA-FDA Fish Advice: Technical Information That dose is meant to be safe over a lifetime and includes a tenfold safety margin.21U.S. Food and Drug Administration. Technical Information on Development of FDA/EPA Advice on Eating Fish It’s also built to protect a developing baby during pregnancy, so it is cautious for other adults.22U.S. Food and Drug Administration. Technical Information on Development of FDA/EPA Advice on Eating Fish
In servings, the FDA and EPA list canned light tuna among the best choices: 2 to 3 servings of 4 ounces a week for adults. Albacore is a good choice, limited to 1 serving a week. Children get smaller portions sized to their age, roughly 1 to 4 ounces. Someone eating tuna salad most days does better with light tuna and some other fish mixed in.
A serving is about 4 ounces of cooked fish, roughly the size of the palm of your hand. A standard 5-ounce can, once drained, comes close, so one can is about one serving.
To work out your own week, two light-tuna cans plus another low-mercury fish fits within advice. Swapping one light can for albacore uses the whole week’s albacore allowance, so the other servings should be low-mercury fish.
The weekly amounts add up across all the fish you eat, so a tuna sandwich at lunch and a tuna steak at dinner both count. Fish in the best-choice group, like salmon or sardines, can fill the remaining servings without adding much mercury.
Canned Tuna During Pregnancy and for Children
Mercury during pregnancy can harm a developing baby’s brain and nerves.23PubMed Central. Mineral and heavy metal content in canned tuna: Implications for veterinary public health and consumer safety Yet eating 2 to 3 portions of fish a week in pregnancy was linked to better child development.24PubMed Central. A review of guidance on fish consumption in pregnancy: is it fit for purpose? Babies of mothers who ate no fish had lower birth weights.25PubMed Central. A review of guidance on fish consumption in pregnancy: is it fit for purpose? The research supports eating fish in pregnancy while avoiding high-mercury kinds.26PubMed Central. Fish consumption, methylmercury and child neurodevelopment
A pregnant woman can aim for about 2 to 3 servings of low-mercury fish a week, matching the amount linked to better child development. Those servings can include one light tuna can, a salmon meal, and another low-mercury fish rather than all tuna.
Light tuna in water combines low mercury with useful omega-3 fats, the benefit tuna offers.27Journal of Food Science. Mercury and Fatty Acids in Canned Tuna, Salmon, and Mackerel Young children and people with chronic illness are also more sensitive to mercury.28PubMed Central. Mineral and heavy metal content in canned tuna: Implications for veterinary public health and consumer safety So pregnant women and parents should favor light tuna.
For kids, toddlers need only about one ounce per serving. School tuna sandwiches can use light tuna a couple of times a week, and mixing tuna with other proteins keeps weekly totals low.
Other Concerns Beyond Mercury
BPA, a chemical in some can linings, turned up in more than 83% of canned seafood tested in Portugal.29PubMed. Determination of bisphenol A and bisphenol B in canned seafood combining QuEChERS extraction with dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry Canned foods tested in Japan, though, stayed within accepted safe daily limits.30PubMed. Concentrations of bisphenol a, bisphenol a diglycidyl ether, and their derivatives in canned foods in Japanese markets Anyone wanting extra caution can choose BPA-free cans or pouches. Pouches and glass jars avoid the issue, though pouches may cost more per serving. The extra caution is most relevant for pregnant women and people who eat canned food daily.
Selenium in fish binds mercury and may offer some protection.31PubMed Central. Selenium and mercury molar ratios in commercial fish from New Jersey and Illinois: Variation within species and relevance to risk communication But how much selenium is needed is unclear, and levels vary between individual fish.32PubMed Central. Selenium and mercury molar ratios in commercial fish from New Jersey and Illinois: Variation within species and relevance to risk communication In larger fish, the protective balance shrinks as size grows.33PubMed Central. Mercury and selenium levels, and selenium:mercury molar ratios of brain, muscle and other tissues in bluefish (Pomatomus saltatrix) from New Jersey, USA So don’t count on selenium; follow mercury limits.34PubMed Central. Selenium and mercury molar ratios in commercial fish from New Jersey and Illinois: Variation within species and relevance to risk communication
Histamine forms when bacteria grow in tuna between catch and eating.35LWT. Scombroid fish poisoning: Factors influencing the production of histamine in tuna supply chain. A review Refrigerate opened tuna and use it within a few days. Histamine poisoning looks like an allergy: flushing, headache, a tingling mouth, or a rash, starting within minutes to an hour of eating. A peppery or metallic taste can be a warning sign, though spoiled tuna often looks and smells normal. Antihistamines usually help, but seek care if breathing is affected.
Lower-Mercury Canned Fish to Rotate In
Canned salmon and mackerel averaged well under a third of canned tuna’s mercury in one US check.36Journal of Food Science. Mercury and Fatty Acids in Canned Tuna, Salmon, and Mackerel They also carried more omega-3 fats than albacore tuna.37Journal of Food Science. Mercury and Fatty Acids in Canned Tuna, Salmon, and Mackerel In stores in Georgia and Alabama, pink and red salmon and mackerel averaged about 35 micrograms per kilogram versus 285 for tuna.38Journal of Food Composition and Analysis. Assessment of trace elements in canned fishes (mackeral, tuna, salmon, sardines and herrings) marketed in Georgia and Alabama (United States of America) Sardines fell in between at about 107.39Journal of Food Composition and Analysis. Assessment of trace elements in canned fishes (mackeral, tuna, salmon, sardines and herrings) marketed in Georgia and Alabama (United States of America) Salmon works in salads and patties much like tuna, while sardines and mackerel suit toast and pasta.
Check the mackerel label, since king mackerel is a high-mercury species unlike Atlantic or chub mackerel. Salmon cans with bones add calcium.