Tuna Fish: Brain-Boosting, Protein Powerhouse or Toxin-Filled Danger Food?

May 7, 2018
Tuna fish - Dr. Axe

by Rachael Link, MS, RD

When you think of health foods, canned tuna might not be the first thing that pops into your mind. Unfortunately, tuna fish has gotten a bad reputation over the years. Despite its multitude of health benefits, it’s considered more of a convenience item or quick dinner option rather than a staple in a nutritious diet.

However, tuna fish is right up there with other healthy types of fish, such as salmon, when it comes to nutrition. It’s low in calories but packs a good amount of protein and heart-healthy omega-3 fatty acids into each serving. It’s also loaded with antioxidants and important micronutrients, giving you all the more reason to make tuna fish a regular part of your diet.


What Is Tuna Fish? Types of Tuna

A tuna is a type of saltwater fish that belongs to the same family as mackerel fish and bonito fish. They are members of the Thunnini tribe, which includes 15 different tuna species. The most common types of tuna include:

  • Albacore tuna
  • Yellowfin (ahi) tuna
  • Skipjack tuna
  • Bluefin tuna
  • Bigeye tuna

The tuna fish size can vary pretty widely between different species; the yellowfin tuna, for example, can be under three pounds while larger varieties like the northern bluefin tuna might weigh up to 1,430 pounds.

Tuna stand out from other types of fish because they are incredibly fast and able to maintain a body temperature above their surroundings. Some types, like the yellowfin tuna, even tend to swim next to dolphins in the Pacific Ocean for protection against predators, such as sharks.

The meat of the tuna fish is often sold frozen, fresh or canned and is widely consumed around the world as a popular ingredient for sandwiches, salads, casseroles and sushi rolls.


Benefits of Tuna Fish

  1. High in Protein
  2. Aids in Weight Loss
  3. Promotes Thyroid Health
  4. Boosts Brain Function
  5. Rich in Antioxidants
  6. Reduces Inflammation

1. High in Protein

Protein is essential to many aspects of health. It makes up the foundation of your hair, skin, nails and muscles; is crucial for the synthesis of certain enzymes and hormones; and is used for the growth and repair of tissues. Not only that, but a protein deficiency can also have detrimental effects on health, resulting in symptoms like impaired immunity, slow wound healing, low energy levels and an increased appetite.

Tuna meat is literally loaded with protein with 42 grams in each can. Combined with just a few other high-protein foods, including even one serving of tuna fish in your diet can help provide your body with the protein that you need.

2. Aids in Weight Loss

Tuna fish is high in protein but low in calories, making it an excellent addition to a weight loss diet. Thanks to its high protein content, in particular, tuna can help reduce your appetite, ward off cravings and keep you feeling fuller for longer.

One study published in the American Journal of Clinical Nutrition showed that eating a high-protein meal led to greater reductions in levels of ghrelin, the hormone responsible for stimulating hunger, than a high-carb meal. It also slowed gastric emptying, resulting in increased satiety. (1) Another study from the University of Washington School of Medicine found that upping protein intake by just 15 percent decreased daily caloric intake by 441 calories and caused a significant reduction in body weight and fat mass. (2)

3. Promotes Thyroid Health

Your thyroid is a butterfly-shaped gland in your neck that’s responsible for regulating your metabolism, producing hormones and maintaining energy levels. Impaired thyroid function can cause serious symptoms, such as changes in weight, body temperature, bowel habits, sexual function and focus. (3)

Tuna nutrition is high in selenium, a mineral that plays a central role in the health of your thyroid gland. In fact, the thyroid gland is considered the organ with the highest amount of selenium per gram of tissue. Multiple studies have found that selenium supplementation may be beneficial for conditions like autoimmune thyroiditis, Graves’ disease and hypothyroidism. (4)

4. Boosts Brain Function

It’s no secret that what you eat can directly impact several aspects of health. In recent years, however, more and more mounting evidence has begun to demonstrate just how crucial your diet may be when it comes to the health of your brain.

Tuna fish is high in several nutrients that have been directly linked to brain health. Niacin, in particular, has been linked to a lower risk of Alzheimer’s disease and age-related decline. (5) Tuna fish is also high in omega-3 fatty acids, which can boost cognitive performance and may be protective against mental health problems like depression. (6, 7)

5. Rich in Antioxidants

Antioxidants are compounds that can help neutralize harmful free radicals to protect against cell damage and chronic disease. A higher intake of antioxidants is thought to prevent the development of conditions like heart disease, diabetes, cancer and certain autoimmune disorders. (8)

Tuna is packed with antioxidant-rich selenium, providing 190 percent of the daily recommended value for selenium in each can. Selenium has antioxidant properties and can help reduce oxidative stress and prevent damage to cells. (9) According to a study published in the World Journal of Biological Chemistry, tuna is also high in a selenium-containing compound called selenoneine, which fights off free radicals and could even protect against chronic disease and aging. (10)

6. Reduces Inflammation

Inflammation is a normal response by the immune system that can help fight off foreign invaders and protect the body from illness and infection. Long-term inflammation, on the other hand, has actually been tied to an increased risk of certain diseases like cancer and heart disease. (11)

Tuna is rich in omega-3 fatty acids, or fish oil, which may be able to alleviate inflammation and reduce the risk of disease. In fact, one of the primary ways that fish oil benefits health is through its potent anti-inflammatory properties, and multiple studies have shown that it could be therapeutic for autoimmune conditions like Crohn’s disease, lupus, rheumatoid arthritis and psoriasis. (12)

 

Tuna fish - Dr. Axe

 


Potential Downsides of Tuna Fish

Despite the multitude of potential tuna fish benefits, there are certain downsides that should be considered as well.

As with nearly any type of fish, the mercury content should be taken into account. Mercury poisoning can cause symptoms like memory problems, numbness, shaking and double vision. Certain types of tuna are higher in mercury than others. Canned white tuna, for instance, contains nearly three times the amount of mercury as skipjack tuna, which is commonly found in canned light tuna. (13)

The FDA recommends that children and pregnant women limit fish consumption to about 12 ounces per week and steer clear of fish with high levels of mercury, such as king mackerel, bigeye tuna, tilefish and swordfish, to prevent adverse effects on health. (14)

If you’re ordering tuna sushi, you should also skip the Hon Maguro, or Atlantic bluefin tuna. Although this type of tuna is a staple in sushi restaurants, it lands on the list of fish you should never eat because it’s been overfished to the brink of extinction. However, because it’s in such high demand, it remains a target of commercial fishing as its population continues to dwindle.

In addition to the environmental and ecological consequences associated with the Atlantic bluefin tuna, this type of tuna is also higher in mercury and is best avoided altogether. (15) It’s also commonly farm-raised, which can be even worse than eating bacon; certain types of farm-raised fish have been shown to contain a higher concentration of toxins and chemicals that can be harmful to health, such as dioxins and pesticides. (16) Instead, opt for other types of tuna in your favorite sushi rolls, such as skipjack tuna caught through Pacific troll or pole and line tuna fishing methods.

If you’re consuming canned tuna, you should also consider the sodium content. Like most canned foods, canned tuna is generally high in sodium, which may be linked to increased levels of blood pressure. (17) Tuna in water is the best canned tuna if you’re looking to cut back on your sodium intake. Rinsing off canned tuna fish can also reduce the sodium content by up to 80 percent as well. (18)


Tuna Nutrition Facts

The nutrition profile of tuna can vary slightly depending on the type of tuna as well as how it’s prepared. For example, there are more calories in canned tuna in oil compared to the amount of calories in canned tuna in water. Tuna steak nutrition also tends to be lower in sodium than canned tuna varieties. In general, however, tuna is low in calories but bursting with protein, selenium, niacin and vitamin B12.

One can (about 165 grams) of light tuna in water contains approximately: (19)

  • 191 calories
  • 42.1 grams protein
  • 1.4 grams fat
  • 133 micrograms selenium (190 percent DV)
  • 21.9 milligrams niacin (110 percent DV)
  • 4.9 micrograms vitamin B12 (82 percent DV)
  • 0.6 milligram vitamin B6 (29 percent DV)
  • 269 milligrams phosphorus (27 percent DV)
  • 558 milligrams sodium (23 percent DV)
  • 2.5 milligrams iron (14 percent DV)
  • 44.6 milligrams magnesium (11 percent DV)
  • 391 milligrams potassium (11 percent DV)
  • 1.3 milligrams zinc (8 percent DV)
  • 0.1 milligram riboflavin (7 percent DV)

In addition to the nutrients listed above, tuna also contains some thiamine, vitamin E, pantothenic acid and copper.


Tuna vs. Salmon

Tuna and salmon may be considered two of the most commonly consumed types of fish, but there are plenty of differences that set them apart.

Tuna has a more mild, less fishy taste while salmon is generally more rich, juicy and tender. Both types of fish can be cooked similarly and are available in fresh and canned forms.

If you compare the cooked salmon and tuna fish nutrition profile per ounce, tuna is slightly higher in protein and lower in calories. It also contains a higher amount of certain micronutrients, such as niacin, phosphorus and vitamin B12. Salmon, on the other hand, is higher in folate and healthy fats, including omega-3 fatty acids.

That being said, both are easy to find, full of beneficial nutrients and can make valuable additions to a balanced meal. Enjoy a serving or two of both per week to maximize the health benefits of your diet.


Where to Find Tuna

Widely available at most grocery stores and supermarkets, finding canned tuna is easier than ever. You’ll typically find tuna in the same aisle as other canned fish, such as salmon and sardines.

However, there are other types of tuna to eat besides canned tuna. You can also often find frozen tuna steaks at most grocery stores, or you can find them fresh if you stop by your local fish market.

The tuna fish price can vary based on the type of tuna you’re purchasing. Canned tuna is generally the most affordable option while fresh bluefin tuna ranks among the most expensive, clocking in between $12–$14 per pound.


Tuna Uses + Tuna Recipes

Although many people think of tuna as a last resort dinner option when the fridge is starting to get empty, it can be so much more than that. You can easily use tuna canned to make a delicious tuna fish sandwich or tuna fish salad. Tuna is also a popular ingredient in sushi rolls, pasta dishes, soups, poke bowls and, of course, tuna fish casserole. Tuna steaks can also be seasoned and grilled, seared or baked and served alongside your favorite side dishes.

Here are some simple tuna fish recipes that you can try out to mix up your weekly routine:


History

According to the National Fisheries Institute, tuna ranks as the second most popular seafood product in the United States after shrimp. In fact, it’s estimated that Americans eat about one billion pounds of canned and pouched tuna every year, or about 2.7 pounds of tuna fish per capita. Plus, nearly half of all households serve canned tuna once a month, and 17 percent consume it every week.

The most popular type of tuna is light meat in water or oil, which accounts for 75 percent to 80 percent of canned tuna consumption overall. Skipjack, in particular, makes up about 70 percent of canned and pouched tuna consumption. Interestingly, tuna consumption changes throughout the year. Americans eat more tuna during the summer and consumption falls in October, November and December. (20)

As awareness of the health benefits of fish continues to grow, consumption steadily increases as well. Health organizations like the American Heart Association generally recommend aiming for at least two servings of fatty fish like tuna per week to get in a hearty dose of important nutrients and omega-3 fatty acids (21)


Precautions

If you have an allergy to fish, you should avoid tuna as well as other types of seafood. Additionally, if you experience any food allergy symptoms after eating tuna, discontinue use and talk to your doctor.

Stick to tuna fish varieties that are low in mercury, and avoid high-mercury fish, such as bluefin tuna and bigeye tuna. Children and pregnant women should keep fish intake in moderation to minimize mercury exposure.

You should also avoid Atlantic bluefin tuna, which may have a negative impact on both the environment and your health because it is overfished and often farm-raised. Stick to wild types of tuna that are caught using the Pacific troll or pole and line methods.


Final Thoughts

  • Tuna is a type of saltwater fish that belongs to the same family as mackerels and bonito fish. The tuna size can vary widely, from under three pounds to over 1,400 pounds based on the species of fish.
  • Tuna is low in calories but high in protein, niacin, selenium and vitamin B12.
  • Adding tuna to your diet can improve weight loss, reduce inflammation, boost brain function and promote thyroid health.
  • Certain types of tuna are high in mercury, overfished and often farm-raised, placing them on the list of health foods you should never eat. For this reason, you should avoid Atlantic bluefin tuna and select healthier varieties like skipjack tuna.
  • Try incorporating tuna into your diet by adding it to your next casserole, salad or tuna sandwich and enjoy the many health benefits that it has to offer.

Read Next: Is Halibut Fish Safe to Eat? Pros & Cons of Halibut Nutrition


Josh Axe

Get FREE Access!

Dr. Josh Axe is on a mission to provide you and your family with the highest quality nutrition tips and healthy recipes in the world...Sign up to get VIP access to his eBooks and valuable weekly health tips for FREE!

Free eBook to boost
metabolism & healing

30 Gluten-Free Recipes
& detox juicing guide

Shopping Guide &
premium newsletter

More Foods