Canned tuna is the ultimate lazy-girl way to get some fish into your diet (because fresh fish gets stanky real quick and can be tricky to cook).
Convenient as the canned stuff is, though, it comes with some questions. Like, uh, how can fish possibly be okay to eat after it’s been hanging out in a can? Is it loaded with heavy metals? Ultimately, is canned tuna actually healthy?
Rest assured: Generally, “canned tuna is a safe alternative to fresh fish,” says Keri Gans, RD, dietitian and author of The Small Change Diet. The processing it undergoes—and sealing of the can—make it shelf-stable.
However, those heavy metal concerns are real. Certain species of tuna contain higher-than-average amounts of mercury, a toxic metal that can cause severe health issues, according to the Environmental Defense Fund (EDF). That’s why you should keep tabs on your canned tuna intake, especially if you’re pregnant.
As a whole, though, “the health benefits of tuna generally outweigh the potential risks associated with trace levels of mercury detected in some tuna,” says dietitian Julie Upton, RD, cofounder of nutrition website Appetite for Health.
Still have questions? Here’s the breakdown of everything you’ve ever wondered about canned tuna.
How do they catch the fish in canned tuna?
The tuna that ends up in cans is caught a few different ways, according to the International Seafood Sustainability Foundation (ISSF). Most is caught using a method called “purse seining,” in which a net is drawn out into the water around a school of tuna. Weights carry one end of the net deep into the water, which is then pulled up to trap the fish once they’re surrounded.
“Long-lining” is another method, in which a long float-supported line is put into the water. Attached to that long line? A whole string of lines sporting baited hooks.
Finally, some tuna are also caught by “trolling” or “pole and line fishing.” In these methods, live bait is dumped into the water to attract the tuna. The fishermen then drop in their individual hooked lines to catch the interested tuna.
Okay. But that tuna ends up in a can…how?
The process that turns a fresh-caught fish into the canned stuff varies a bit from company to company.
Bumble Bee, for example, says their tuna is delivered to their cannery from the fishing boats—or from reefer ships, which deliver the tuna from foreign fishing companies.
From there, the tuna is frozen and grouped according to size and weight.
Then, it’s inspected, thawed, cleaned, loaded onto metal racks, and baked. Once cooked, the tuna’s skin and bones are removed and the remaining meat moves on to be canned.
The meat is added to cans, which are automatically filled with the fish, salt, vegetable broth, water, or oil (depending on the variety). The lids are then attached and sealed, and the cans are cleaned and sterilized.
And is that canned tuna healthy? Talk to me about nutrition.
When you hit up the canned goods aisle at the supermarket, you’ve got lots of tuna options—including different types of tuna prepared in different ways.
The most commonly eaten type of tuna in the U.S. is skipjack (which is also what most “light tuna” is made from), according to Starkist. White tuna, a.k.a. albacore, is another popular option.
Generally, these different types of tuna offer similar nutrition.
The most notable nutritional differences amongst cans of tuna stem from whether they’re packed in oil or water—and how much sodium they contain. (The only real difference between oil- and water-packed tuna is the calories and fat, says Gans.)
Here’s what you can expect from a one-ounce serving of canned tuna, packed in oil, according to the USDA Nutrient Database:
- Calories: 56
- Fat: 2.3 g
- Protein: 8.3 g
- Carbohydrates: 0 g
- Fiber: 0 g
- Sodium: 416 mg
And, from a one-ounce serving of canned tuna, packed in water, according to the USDA Nutrient Database:
- Calories: 24
- Fat: 0.3 g
- Protein: 5.5 g
- Carbohydrates: 0 g
- Fiber: 0 g
- Sodium: 247 mg
In addition to being a great protein source, canned tuna also contains key nutrients like vitamin D and omega-3 fatty acids, says Jessica Cording, RD, dietitian and author of The Little Book of Game-Changers: 50 Healthy Habits For Managing Stress & Anxiety.
“Vitamin D and omega-3s are both essential nutrients for brain development and cognitive function, as well as reduction of inflammation,” she says. Vitamin D also plays an important role in bone health, immune system function, and cell growth, while omega-3s help support cell structures.
Cool. So how much tuna can I eat per week?
Concerns about how much tuna is safe to eat come back to the mercury situation.
Certain types of tuna typically contain more mercury than others, with light tuna being your safest bet. “The reason light tuna is generally lower in mercury is because it’s made from smaller, younger fish that haven’t had as much time to absorb the heavy metal,” Cording explains. Albacore, meanwhile, typically packs more.
The average person can safely eat up to 12 ounces of light tuna—or up to five ounces of albacore tuna—a week, Gans says.
If you’re pregnant or breastfeeding, though, the Food and Drug Administration (FDA) recommends consuming between eight and 12 ounces of a “variety of seafood” per week. That means no more than two to three servings of light tuna per week, per the FDA.
What does a quality can of tuna look like?
Next time you’re in the canned goods aisle, make sure your can of tuna meets the following four criteria to ensure it’s the highest quality possible.
- It’s light tuna. (Again, see mercury concerns.)
- It has a limited ingredients list. You really want a can in which the only ingredients are tuna, water or oil, and maybe salt, Cording says.
- It features pole-caught tuna. “Because overfishing is a concern with tuna, keep in mind that pole-caught tuna better supports sustainability,” Cording says.
- It has certifications. Brands certified by the Marine Stewardship Council (MSC), the Monterey Bay Aquarium, or the Safina Center tend to be more sustainable, Gans says.
Bonus: Pick a brand that tests their tuna for mercury and other contaminants, says Sonya Angelone, RD, dietitian and spokeswoman for the Academy of Nutrition and Dietetics. “It should say right on the can,” she says.
Sweet. And the best ways to eat canned tuna are…?
Canned tuna can be a healthy part of your diet—as long as you don’t eat it every day.
Toss a little tuna on top of salads for extra protein, spread tuna on crackers and add a squeeze of fresh lemon, or mix with avocado, salsa, or Greek yogurt for a zesty dip.
However you like it, give yourself a pat on the back for getting a little more seafood into your diet.
The bottom line: Canned tuna is generally healthy, just opt for “light tuna” and don’t eat the stuff every day to be mindful of your mercury consumption.
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