A meaty ocean fish with a nutrient list that punches above its weight.
Swordfish has a reputation as a steak-like fish, thick, firm, and satisfying in a way that flakier white fish rarely manages. Behind that texture sits a genuinely useful nutrient profile: omega-3 fats, vitamin D, and selenium, three things your body leans on for a surprising number of jobs. It also carries a real caveat around mercury, which we’ll get to honestly rather than bury at the end.
If you’ve been eyeing a swordfish steak at the counter and wondering whether it earns a place on your plate, here’s what the evidence actually says, plus a couple of ways to cook it well.
Key Takeaways
– Swordfish is a large predatory fish found in warm and temperate waters of the Atlantic, Pacific, and Indian oceans.
– It’s a strong source of selenium and vitamin D, two nutrients your body can’t make on its own.
– Its omega-3 fats (EPA and DHA) are linked to lower blood pressure and better blood vessel function.
– The same nutrients may support brain function, vision, bone strength, and immune response.
– Mercury content is the main reason to keep portions modest, especially during pregnancy.
A Quick Look at This Ocean Predator
Swordfish (Xiphias gladius) is a large, migratory billfish named for the long, flattened bill it uses to stun the squid and smaller fish it hunts. Adults have big eyes, a rounded body, and, unusually, no teeth or scales once fully grown. Some reach striking sizes, with lengths reported up to around 15 feet.
They’re prized by both commercial fleets and recreational anglers, typically caught with longlines or harpoons. In warmer months they migrate toward colder, feeding-rich waters. All of that hunting and traveling is part of why an older, larger swordfish accumulates mercury, a detail worth holding onto for later.
What’s Inside a Swordfish Steak
SavePer 100 grams, raw swordfish delivers lean protein alongside its standout micronutrients. The three that matter most:
Omega-3 fatty acids — mainly EPA and DHA, the marine fats tied to heart and brain health.
Selenium — a trace mineral your body builds into selenoproteins.
Vitamin D — the “sunshine vitamin” many people run low on.
Here’s the part that makes swordfish more than just protein: your body cannot manufacture selenium or vitamin D, so you have to get them from food or sun. A fish that supplies both, plus omega-3s, is doing a fair amount of work in one serving.
What Swordfish May Do for Your Body
The benefits below all trace back to that omega-3, selenium, and vitamin D trio. None of them are magic, and most come from broader research on those nutrients rather than swordfish specifically, but the connections are well documented.
Heart support
SaveThis is the strongest case. Clinical trials have found that EPA and DHA can reduce the risk of heart-related deaths, with roughly 0.5 to 1.8 grams a day linked to better outcomes. Those fats appear to lower blood pressure and improve how blood vessels function. Selenium matters here too, particularly for people at risk of heart failure, and vitamin D3 plays a role in keeping vessels and heart function healthy.
Brain and cognition
Vitamin D is involved in brain development and function, and DHA is a structural building block of the brain that’s consistently tied to sharper cognition. Selenium, carried as selenoproteins, helps protect neurons; keeping blood and brain levels balanced supports healthy nerve cell survival.
Vision
The same marine fats may calm inflammation in the eyes. EPA and DHA have been associated with a lower risk of dry eye disease and age-related macular degeneration, largely through their anti-inflammatory effect.
Bones and calcium
SaveVitamin D is the quiet hero of bone health because it governs how well you absorb calcium. Without enough of it, your gut takes up only about 10 to 15 percent of the calcium you eat; with adequate vitamin D, that can rise to 30 to 40 percent. Selenium supports bone development, and omega-3s have been linked to higher bone mineral density in women.
Joints and immunity
There’s early evidence that omega-3s (around 2.6 grams daily in one study) can ease rheumatoid arthritis symptoms, and adequate vitamin D may lower RA risk in women over 50. If achy joints are on your radar, swordfish fits neatly into an anti-inflammatory eating pattern. On the immune side, omega-3s help immune cells do their job, vitamin D shapes the body’s defense response, and selenium can make a real difference for people whose levels run low.
One benefit worth flagging as less settled: the cancer connection. Omega-3s and vitamin D both have anti-inflammatory properties, and some research suggests they may help slow the spread of cancer cells, especially in the colon. It’s promising, but this isn’t a reason to treat fish as a treatment.
Cooking Swordfish at Home
SaveSwordfish shows up often in Mediterranean kitchens, and for good reason. The flesh is tender and slightly sweet, and its density holds up to grilling, broiling, or a hard sear where more delicate fish would fall apart. Because it’s high in protein and carries almost no carbohydrate, it slots easily into low-carb meals without much fuss.
A simple approach: brush a 200-gram steak with olive oil and lemon juice, then grill it over high heat for several minutes a side until firm and opaque. From there you can dress it up. Cut a pocket into the steak and stuff it with wilted spinach and crumbled feta for a Greek-style plate, or top a grilled steak with cherry tomatoes, olives, and a splash of red wine vinegar. A scatter of fresh parsley at the end brightens the whole thing and adds a little extra nutrition on the side.
A Word on Mercury and Who Should Be Careful
Here’s the honest trade-off. Swordfish sits near the top of the ocean food chain and lives a long time, which means it accumulates more mercury than smaller fish. That’s the main reason health agencies recommend eating it only occasionally rather than weekly, and why pregnant people, those trying to conceive, and young children are generally advised to skip it. High mercury intake can also be a concern for people managing diabetes.
Anyone with a seafood or fish allergy should avoid it entirely. For most other healthy adults, swordfish is fine as an occasional treat, the key word being occasional. Variety across lower-mercury fish is the safer long-term habit.
Frequently Asked Questions
Is swordfish healthy to eat regularly?
It’s nutritious, but its mercury content means it’s better as an occasional choice than a staple. Rotating in lower-mercury fish like salmon or sardines lets you get omega-3s more often without the same mercury load.
Can pregnant women eat swordfish?
It’s typically on the “avoid” list during pregnancy because of mercury, which can affect fetal development. If you’re pregnant or breastfeeding, check with your healthcare provider and lean toward lower-mercury options.
What does swordfish taste like?
Mild and slightly sweet, with a firm, meaty texture closer to a steak than to flaky white fish. That density is exactly why it grills and sears so well.
The Bottom Line
Swordfish earns its spot as a nutrient-dense fish, delivering omega-3 fats, vitamin D, and selenium that together support your heart, brain, eyes, bones, and immune system. The catch is mercury, which keeps it in the “sometimes” category rather than the everyday one. Enjoyed in modest portions, grilled simply and paired with vegetables, it’s a flavorful way to fold those hard-to-get nutrients into your diet, as long as you’re not pregnant or allergic to fish.
This article is for informational purposes only and is not a substitute for professional medical advice. Talk with a qualified healthcare provider before making significant changes to your diet, especially if you are pregnant, nursing, or managing a health condition.