Most adults can safely eat canned light tuna two to three times per week, while albacore (white) tuna and yellowfin should be limited to once per week or less. The difference comes down to mercury, which builds up in larger, longer-lived tuna species at significantly higher concentrations. Knowing which type of tuna you’re eating matters more than simply counting cans.
Why the Type of Tuna Changes Everything
Not all tuna is created equal when it comes to mercury. Canned light tuna, which is typically skipjack, contains about 0.126 ppm of mercury. Albacore (the white tuna you see on store shelves) comes in at roughly 0.350 ppm, nearly three times as much. Yellowfin runs similar to albacore at 0.354 ppm, and bigeye tuna tops the chart at 0.689 ppm.
The FDA groups these into tiers. Canned light tuna (skipjack) falls in the “Best Choices” category, meaning you can eat two to three servings per week. Albacore and yellowfin land in the “Good Choices” tier, where the recommendation drops to one serving per week. Bigeye tuna is on the “Choices to Avoid” list entirely. A standard serving for adults is 4 ounces, roughly the size of the palm of your hand.
The Biodiversity Research Institute’s analysis is even more conservative for albacore and yellowfin, suggesting just one meal per month for both species based on their average mercury concentrations exceeding the 0.22 ppm consumption guideline. If you eat tuna frequently and want the widest safety margin, sticking with skipjack is the simplest approach.
How Mercury Builds Up in Tuna
Mercury enters the ocean from both natural sources and industrial pollution. In subsurface waters, bacteria convert inorganic mercury into methylmercury, a form that living organisms absorb easily but eliminate slowly. Tiny organisms take it in first, small fish eat those organisms, and larger predators eat the small fish. At each step, mercury concentrations increase. This process, called biomagnification, is why a large predatory fish like tuna carries far more mercury than the small fish it feeds on.
Species that live longer and grow larger accumulate more. Skipjack tuna tend to stay in shallow surface waters and are relatively small, which keeps their mercury levels low. Bigeye tuna, by contrast, dive deeper into oxygen-poor waters where methylmercury concentrations peak, and they live longer, giving the toxin more time to build up in their tissue. A single bigeye tuna steak can contain five times the mercury of a can of light tuna.
Fresh Tuna Steaks vs. Canned Tuna
Fresh tuna from a restaurant or fish counter is not automatically higher in mercury than canned, but it often is in practice. Canned light tuna uses skipjack, the lowest-mercury species. Fresh tuna steaks are usually yellowfin (ahi) or albacore, both of which carry roughly 0.350 ppm of mercury. Fresh or frozen bigeye, sometimes also sold as ahi, runs even higher at 0.689 ppm.
The key question at a restaurant or sushi bar is which species you’re getting. If the menu says “ahi tuna,” it could be yellowfin or bigeye. Yellowfin is the safer bet, but if the restaurant can’t tell you which species it is, treat it like a “Good Choices” fish and limit yourself to one serving that week.
Guidelines During Pregnancy and Breastfeeding
The FDA’s recommendations for pregnant and breastfeeding people follow the same tier system: two to three 4-ounce servings per week of “Best Choices” fish like canned light tuna, or one 4-ounce serving per week of “Good Choices” fish like albacore or yellowfin. The stakes are higher during pregnancy because methylmercury crosses the placenta and can affect fetal brain development. The EPA’s reference dose for methylmercury was specifically set based on developmental neurological effects in children.
This doesn’t mean you should avoid tuna entirely during pregnancy. Fish provides omega-3 fatty acids, protein, and other nutrients that support fetal development. The goal is choosing lower-mercury options and staying within the serving limits. Two cans of light tuna per week is a reasonable, safe habit during pregnancy.
How Much Tuna Children Can Eat
Children can eat tuna, but their serving sizes are much smaller than an adult’s. The FDA recommends kids eat two servings per week from the “Best Choices” list, which includes canned light tuna. Serving sizes scale with age:
- Ages 1 to 3: 1 ounce per serving
- Ages 4 to 7: 2 ounces per serving
- Ages 8 to 10: 3 ounces per serving
- Age 11 and up: 4 ounces per serving
For young children especially, stick with canned light tuna rather than albacore or yellowfin. A child’s developing nervous system is more vulnerable to mercury, and their smaller body weight means the same amount of mercury has a proportionally larger effect.
Signs You May Be Eating Too Much
Chronic low-level mercury exposure from fish typically doesn’t cause dramatic symptoms right away. Over time, methylmercury damages the central nervous system. Early signs can include problems with coordination and movement, difficulty concentrating, and numbness or tingling in the hands and feet. At higher exposure levels, more serious effects include vision and hearing changes, impaired mental functioning, and seizures.
These symptoms generally develop from sustained, excessive consumption well beyond the recommended limits, or from occupational exposure. If you’ve been eating tuna daily for an extended period and notice coordination problems or cognitive changes, a simple blood test can check your mercury levels. Mercury clears from the body over weeks to months once you reduce your intake.
Practical Tips for Regular Tuna Eaters
If tuna is a staple in your diet, a few habits can keep your mercury exposure well within safe limits. Buy canned light (skipjack) tuna as your default. It’s cheaper, lower in mercury, and safe at two to three cans per week for adults. Save albacore and yellowfin for occasional meals rather than daily lunches.
Rotate tuna with other low-mercury fish. Salmon, sardines, tilapia, shrimp, and pollock are all in the FDA’s “Best Choices” category and provide similar nutritional benefits. Variety also gives you a broader range of nutrients.
Some brands test each individual fish for mercury before canning. Safe Catch, for example, sets a mercury limit of 0.1 ppm for their skipjack and yellowfin products, which is ten times lower than the FDA’s action level of 1.0 ppm. Their albacore is tested to 0.38 ppm. These products cost more, but they offer an extra layer of assurance if you eat tuna frequently or are feeding it to children.