Tuna is one of the most heart-healthy proteins you can eat. It delivers omega-3 fatty acids that lower triglycerides, contains protein fragments that help regulate blood pressure, and provides selenium that offsets its mercury content. The American Heart Association recommends eating fish at least twice a week, with fatty fish like tuna as a top choice, in servings of about 3 ounces cooked.
That said, not all tuna is equal. The species you choose, how it’s packed, and how often you eat it all shape whether you’re getting a net benefit or introducing risks. Here’s what matters.
How Tuna Protects Your Heart
The headline benefit is omega-3 fatty acids, specifically EPA and DHA. These fats reduce triglycerides, a type of blood fat that raises cardiovascular risk when elevated. At higher doses (around 3.4 grams per day of EPA and DHA), research published in The American Journal of Clinical Nutrition found triglyceride levels dropped by 27% compared to placebo. A typical 3-ounce serving of tuna won’t deliver that much omega-3 on its own, but eating it regularly as part of a broader fish habit contributes meaningfully over time.
Omega-3s also reduce inflammation in blood vessel walls, slow the buildup of arterial plaque, and help stabilize heart rhythm. These effects compound with consistent intake, which is why guidelines focus on weekly habits rather than occasional meals.
Beyond omega-3s, tuna contains bioactive peptides, small protein fragments released during digestion that act as natural ACE inhibitors. ACE inhibitors are the same mechanism used by common blood pressure medications. Researchers have identified dozens of these peptides in skipjack, bigeye, and Atlantic tuna, sourced from muscle tissue and other parts of the fish. While the effect from eating a serving of tuna is modest compared to prescription medication, it adds another cardiovascular layer to an already beneficial food.
The Mercury Question
Mercury is the main reason people hesitate about tuna, and the concern is legitimate. Methylmercury, the form found in fish, can counteract the cardioprotective effects of fish consumption and promote cardiovascular disease at high enough exposure levels. So the question isn’t just whether tuna has mercury. It’s whether the mercury overwhelms the benefits.
This is where selenium matters. Selenium is a mineral that binds to mercury and helps neutralize its toxicity. Scientists measure the selenium-to-mercury molar ratio to gauge how protective a given fish is. A ratio below 1 means more mercury than the selenium can handle. Ratios above 1 mean the selenium provides a buffer. Canned light tuna has a ratio of about 23 to 1, meaning it carries far more protective selenium than harmful mercury. Canned white (albacore) tuna comes in around 7 to 1, and yellowfin tuna steak sits near 3 to 1. All of these are well above the safety threshold.
In practical terms, canned light tuna (typically skipjack) is the safest everyday choice. Albacore and yellowfin are still net-positive for heart health but carry more mercury per serving, so varying your intake across species is a reasonable strategy.
Canned in Water vs. Oil
The packaging liquid changes the nutritional profile more than most people expect. Per 100 grams, tuna canned in vegetable oil contains roughly 848 milligrams of omega-3s, while tuna canned in water with added salt contains about 227 milligrams. That’s nearly four times the omega-3 content in oil-packed tuna.
The trade-off is fat and calories. Oil-packed tuna has about 14 grams of fat per 100-gram serving compared to just 1 gram for water-packed. The sodium levels are similar, around 274 to 297 milligrams per 100 grams, so neither version is dramatically saltier than the other.
If your primary goal is omega-3 intake for heart health and you’re not watching total fat, oil-packed tuna delivers more of what you’re after. If you’re managing weight or total calorie intake, water-packed keeps things lean while still providing some omega-3s. You can also look for brands packed in olive oil, which adds heart-healthy monounsaturated fats rather than the less beneficial vegetable oils.
How Much Tuna Per Week
The American Heart Association recommends two servings of fish per week, particularly fatty fish. A serving is 3 ounces cooked, roughly three-quarters of a cup of flaked fish, or about the size of a deck of cards. Two to three servings of tuna per week fits comfortably within that guideline for most adults.
For people who are pregnant or nursing, the calculus shifts because of mercury sensitivity during fetal development. In that case, light canned tuna is generally considered safer than albacore, and total fish intake guidelines are more conservative.
One important note: the triglyceride-lowering benefits seen in clinical studies used doses of omega-3s that are difficult to reach through food alone. At a lower dose of 0.85 grams per day, one study found no significant change in triglyceride levels. Two servings of tuna a week likely puts you somewhere between that lower threshold and the effective higher dose, depending on the species and preparation. If you have significantly elevated triglycerides, food sources alone may not be enough, and concentrated omega-3 supplements are sometimes used alongside dietary changes.
Fresh Tuna vs. Canned
Fresh tuna steaks (yellowfin, bluefin, ahi) tend to have higher omega-3 content per serving than canned varieties, but they also carry more mercury. Bluefin tuna in particular is one of the higher-mercury fish available. A fresh tuna steak once or twice a week is a reasonable frequency for most adults, but eating it daily could push mercury exposure into less favorable territory.
Canned tuna is more practical for most people and, especially in its light variety, offers an excellent ratio of benefits to risks. It’s affordable, shelf-stable, and easy to add to salads, sandwiches, or pasta without much preparation. For consistent, everyday heart health, canned light tuna is hard to beat as a protein source.