Last Tuesday I stood in the canned fish aisle at my local grocery store for an embarrassingly long time. Like, long enough that another shopper asked if I was okay. I was staring at two cans of tuna that looked nearly identical — same price, same brand, roughly the same packaging — but one said “light” and the other said “white.” I’d never really thought about the difference before. Turns out, that single word on the label can mean a pretty dramatic difference in what you’re actually putting in your body.
“Light” and “white” are not the same fish
Here’s the thing most people miss: “light” and “white” on a canned tuna label refer to completely different species. White tuna is almost always albacore, a larger fish that grows slowly and lives a long time. Light tuna, on the other hand, is typically skipjack — a smaller, faster-maturing species. And that size difference isn’t just trivia. It has real consequences for your health.
The bigger and older a fish gets, the more mercury it accumulates in its body. Albacore tuna — the “white” stuff — can contain up to three times more mercury than light canned tuna. According to FDA data, light canned tuna clocks in at about 0.126 parts per million of mercury. Albacore? Roughly 0.35 PPM. That’s not a small gap.
So if you’ve been grabbing whichever can is cheapest or has the nicest-looking label, you might want to reconsider. A few seconds of label reading could make a meaningful difference, especially if tuna is a regular part of your diet.
Mercury builds up — and tuna eats other fish
Almost all fish have some mercury in them. That’s just the reality of living in water that’s been contaminated with heavy metals over decades of industrial activity. But tuna is a predator. It eats smaller fish. Those smaller fish already have mercury in their systems, and when tuna consumes them, those mercury levels stack on top of each other. Biologists call this bioaccumulation, and it’s why predatory fish tend to carry heavier metal loads than, say, sardines or anchovies.
Among tuna species, the numbers vary wildly. Fresh or frozen yellowfin sits around 0.354 PPM. Bigeye tuna is the worst offender at 0.689 PPM — which, honestly, is kind of alarming for a fish people eat regularly. Skipjack and light varieties stay much lower. The FDA tracks these numbers across species, and the gap between the best and worst options is massive. We’re talking five to six times more mercury in bigeye compared to light canned tuna.
Even the same brand can vary hugely
This one caught me off guard. You’d think buying the same brand would at least give you some consistency. Not necessarily. A Consumer Reports study found that Chicken of the Sea’s albacore canned tuna had ten times more mercury than its own light tuna variety. Ten times. Same company, same shelf, wildly different mercury content.
Meanwhile, Wild Planet’s albacore and skipjack varieties actually tested at similar mercury levels. So the brand matters, the species matters, and sometimes even the individual can matters. One in five cans tested by Consumer Reports had mercury levels significantly higher than the average for that product. That’s a 20% chance of getting an outlier. Not great odds if you’re eating tuna multiple times a week, and especially concerning if you’re pregnant or feeding it to young kids.
Consumer Reports went so far as to recommend that pregnant people avoid canned tuna altogether. The FDA is a bit more lenient, saying two to three servings per week is fine for most people, including children and those who are breastfeeding. But for albacore specifically? Some experts say adults should cap it at five ounces per week.
What mercury actually does to your body
Okay, so mercury levels vary. But does it actually matter for your health? Unfortunately, yes. Mercury poisoning isn’t just some abstract concern from a chemistry textbook. For adults with no underlying health issues, eating high-mercury fish regularly can cause fatigue — the kind where you’re dragging yourself through the day for no obvious reason. Over time, it can lead to fertility problems, trouble regulating blood pressure, and even memory loss.
Kids face even steeper risks. Mercury exposure in children has been linked to learning disabilities and developmental delays. Their smaller bodies and developing nervous systems make them more vulnerable. This isn’t meant to scare you away from tuna entirely — it’s still packed with protein, omega-3s, and important nutrients. But it does mean the type of tuna you pick matters more than most people realize. Choosing light over white is one of the simplest dietary swaps you can make for a real health benefit.
Oil-packed vs. water-packed changes more than you’d think
On the flip side of the mercury question, there’s another label detail worth paying attention to: what the tuna is packed in. Water-packed tuna is the default “healthy” choice for a lot of people. Fewer calories. Less fat. Seems like a no-brainer. But water-packed tuna also loses some of its omega-3 fatty acids to the surrounding liquid. And it dilutes the fish’s natural flavors, which is partly why a lot of people find canned tuna kind of bland and watery. Because it literally is.
Oil-packed tuna — usually packed in vegetable or soy oil — holds onto more of those nutrients. It also seals in more flavor, giving you a richer taste. The trade-off is more calories and fat. For a tuna salad where you’re already adding mayo, the calorie difference probably doesn’t matter much. For eating straight out of the can (no judgment), oil-packed genuinely tastes better. It’s one of those situations where neither option is objectively “right” — it depends on what you’re using it for.
Fishing methods show up on the label too
While mercury gets most of the attention, there’s a completely different angle to canned tuna labels that affects the ocean rather than your body. The fishing method used to catch the tuna matters — a lot. Industrial long-line operations and massive nets harvest thousands of fish daily, and they’re not exactly selective about what they pull in. Bycatch — the unintended capture of other marine life like dolphins, sea turtles, and sharks — is a serious problem with certain fishing practices.
Look for labels that mention “pole-caught,” “pole and line,” or “trawl” methods. These tend to be more targeted and cause less collateral damage. Terms like “school-caught” or “free school” are also good signs, indicating the company is taking steps to reduce bycatch. Here’s a useful rule of thumb: companies that fish responsibly tend to advertise that fact pretty loudly on their packaging. If the can is silent about how the fish was caught, that silence probably tells you something.
Skipjack tuna gets a bonus point here too. Because it matures faster than larger species like albacore or yellowfin, skipjack populations can replenish more quickly. Choosing skipjack isn’t just better for your mercury intake — it’s generally better for the ocean’s long-term health.
Cans, pouches, and what’s actually holding your fish
There’s one more thing on that label worth checking, and it has nothing to do with the fish itself. It’s about the container. Plastic tuna pouches have gotten popular because they’re lightweight and you don’t need a can opener. Convenient, sure. But they cost more per ounce, and without rigid sides, the fish inside can get pretty mushed up if your grocery bag has a rough ride home. Cans protect the texture better and typically have a longer shelf life — around four years on average compared to pouches.
But not all cans are equal either. Cheaper varieties sometimes use materials that may contain BPA, a chemical that’s been linked to various health concerns. Look for cans labeled “BPA-free” if that’s something you care about. And plenty of brands now offer pop-top lids, which means you get the durability of a can without needing to dig through your kitchen drawers for an opener. Small detail, big convenience.
If you want to skip the tuna question entirely, there are alternatives worth considering. Canned sardines clock in at just 0.013 PPM of mercury. Anchovies aren’t far behind at 0.016 PPM. Canned salmon sits at 0.014 PPM, though I’ll be honest — canned salmon is an acquired taste that I have not yet acquired.
A quick label check goes a long way
None of this means you need to quit tuna. It’s still a cheap, protein-rich food that belongs in most pantries. But spending five extra seconds reading the label — checking for “light” or “skipjack,” looking at the packing medium, scanning for fishing method info — can meaningfully reduce your mercury exposure and help you make a smarter purchase. The funny thing is, the better option is usually the cheaper one too, since light tuna tends to cost less than white albacore.
What I keep thinking about, though, is how the labeling rules for seafood in the U.S. don’t always require companies to tell you exactly which species is in the can. Some brands are vague on purpose. That feels like a problem worth paying more attention to — and a pretty good reason to stick with brands that are upfront about what they’re selling you.
