Most adults can safely eat canned light tuna (skipjack) two to three times per week, or canned white tuna (albacore) once per week. The difference comes down to mercury: skipjack tuna contains roughly half the mercury of albacore, so you get more servings before reaching a concerning level. A standard serving is about 4 ounces, or roughly the size of your palm.
Light Tuna vs. White Tuna: Why It Matters
Not all canned tuna is the same fish. “Light” tuna is typically skipjack, a smaller species that sits lower on the food chain and accumulates less mercury. Skipjack averages around 0.14 parts per million (ppm) of mercury. “White” or albacore tuna averages about 0.35 ppm, more than double the skipjack level. Yellowfin tuna, sometimes sold as “chunk light” or as tuna steaks, lands in a similar range to albacore at around 0.35 ppm.
The FDA categorizes skipjack (canned light) as a “Best Choice” fish and albacore as a “Good Choice.” In practical terms, that means you can eat two to three servings of light tuna per week, or one serving of white tuna per week. You shouldn’t combine both in the same week and treat the totals as separate allowances. If you eat a can of albacore on Monday, that’s your tuna for the week.
How Mercury Builds Up
The mercury in tuna is methylmercury, an organic form that your body absorbs efficiently and eliminates slowly. It has a half-life of about 70 to 80 days in the human body, meaning it takes months to clear. Eating tuna occasionally isn’t a concern, but eating it daily lets mercury accumulate faster than your body can remove it.
The EPA sets a safe daily intake at 0.1 micrograms of methylmercury per kilogram of body weight. For a 150-pound adult, that works out to roughly 6.8 micrograms per day. A single 4-ounce serving of canned light tuna contains about 16 micrograms of mercury, while the same serving of albacore contains around 40 micrograms. Spread across a week, two to three cans of light tuna keeps you well within the safe zone. A can of albacore every day would push you over.
What Happens if You Eat Too Much
Occasional overindulgence isn’t dangerous. The concern is sustained, long-term overconsumption. Adults exposed to excessive methylmercury over time can develop symptoms including numbness, muscle weakness, difficulty walking, memory problems, depression, and changes in vision or hearing. Some people describe a persistent metallic taste. These effects develop gradually and are often reversible once mercury levels drop, though recovery can take months.
For most people who eat a couple cans of tuna a week, none of this is relevant. The guidelines exist with a substantial safety margin built in.
Tuna During Pregnancy
Pregnant and breastfeeding women follow the same FDA framework but with higher stakes. Methylmercury crosses the placenta, and developing brains are far more sensitive to its effects. Exposure during pregnancy can affect a child’s intelligence, memory, motor skills, and attention.
The FDA recommends pregnant women eat two to three servings (4 ounces each) per week from the “Best Choices” list, which includes canned light tuna, or one serving from the “Good Choices” list, which includes albacore. That means up to 8 to 12 ounces of light tuna per week is considered safe during pregnancy. Albacore should stay at 4 ounces per week or less. Avoiding fish entirely isn’t ideal either, since omega-3 fatty acids support fetal brain development.
Serving Sizes for Children
Children can eat canned light tuna twice a week, but their serving sizes are smaller to match their body weight:
- 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: 4 ounces per serving
Stick with canned light (skipjack) for kids. Albacore’s higher mercury concentration makes the margin of safety uncomfortably thin for smaller bodies.
The Nutritional Upside
Tuna is one of the most affordable sources of omega-3 fatty acids, protein, and selenium. A 3-ounce serving of canned light tuna provides 200 to 500 milligrams of EPA and DHA, the omega-3s linked to heart and brain health. Albacore is even richer, delivering 500 to 1,000 milligrams per 3-ounce serving. Most health organizations recommend at least 250 milligrams of EPA and DHA daily, so even a modest tuna habit covers that easily.
This is why the guidelines don’t say “avoid tuna.” The nutritional benefits of eating fish two to three times per week are well established. The goal is to choose lower-mercury options more often, not to eliminate seafood.
Lower-Mercury Alternatives
If you love canned fish and want to eat it more than a few times a week, rotating in lower-mercury options gives you more flexibility. Sardines, anchovies, and canned mussels all contain significantly less mercury than any type of tuna because they’re smaller, shorter-lived fish. Canned salmon is also a strong option with low mercury and high omega-3 content. Smaller mackerel species (chub, Pacific, or jack mackerel) are another good swap, though king mackerel should be avoided entirely due to very high mercury levels.
A practical approach: eat canned light tuna two or three times a week, mix in sardines or salmon on other days, and save albacore or yellowfin for an occasional treat rather than a daily staple. That way you get the protein and omega-3s without pushing your mercury intake anywhere near concerning levels.