Why avoid canned tuna?

Why You Might Want to Think Twice About Canned Tuna

It’s a pantry staple in many homes—quick, affordable, and packed with protein. But there’s a hidden downside to reaching for that can of tuna too often: mercury. Canned tuna is one of the most common dietary sources of mercury exposure, a toxic metal that accumulates in fish over time, especially in larger, longer-lived species.

Not all tuna is created equal. The type matters. Skipjack, often sold as “light tuna,” tends to be lower in mercury because it’s smaller and shorter-lived. But albacore, also known as white tuna, comes from a larger species and typically contains significantly more mercury. Bigeye and yellowfin tuna fall somewhere in between, but frequent consumption can still pose risks, especially for pregnant people, young children, and those planning families.

The reason? Mercury enters the environment from natural sources and human activities like coal burning and industrial pollution. It settles in waterways, where bacteria convert it into methylmercury—the form that builds up in fish. As tuna are predatory and high on the food chain, they accumulate mercury over years, making regular consumption a concern.

That doesn’t mean you need to cut canned tuna out entirely. Moderation is key. The FDA and EPA suggest limiting albacore to no more than one serving per week and being more cautious with bigeye. Choosing light tuna in moderation—about 2–3 servings per week—can be a safer option for most adults.

So next time you’re stocking the pantry, read the label. Know the type of tuna you’re buying, and consider rotating in lower-mercury fish like salmon, sardines, or mackerel. A little awareness goes a long way in keeping your meals both convenient and safe.