Until 2013 (when salmon surged ahead), tuna was the second-most popular seafood consumed in the U.S. And it’s not only in the U.S. that tuna is a favorite.
If you’ve ever been to a sushi restaurant, you’ve likely noticed that some of the most common cuts of sashimi are maguro and toro—in other words, types of tuna.
Fish is regularly touted as a very nutritious food, but it’s also common to hear warnings about certain seafood, including tuna.
So should you regularly consume tuna?
The main concern I hear about tuna is its mercury content.
Mercury poisoning is a scary thought, and we’ve all heard about the dangers of playing with old thermometers. Studies have shown that in rats and other animals, a diet excessively high in mercury can lead to stunted growth, deformed limbs, and mental disease.
However, the mercury concern in tuna (and in fish in general) is very much overstated, except in certain circumstances.
I won’t go into a great deal of detail in this article, but the short version is this: No good studies have ever shown any problem with eating seafood “high” in mercury other than a few species like shark and whale, or fish from polluted areas. The reason that these certain cases exist is because mercury’s harmful effects occur when it is in excess of selenium. And for almost all seafood (including tuna), selenium is higher than mercury.
If you want to read more on this issue, check out Chris Kresser’s great article.
On the other hand, tuna has many nutritious qualities that make consumption a great idea. It tends to be high in omega-3s, which are great anti-inflammatories that have shown tendencies to reduce heart disease and high blood pressure, in addition to calming down allergies and asthma.
Even better, tuna is rich in selenium, a nutrient that helps to normalize our bodies—it regulates our thyroid and hormones, assists with DNA synthesis, and protects our bodies from oxidative damage and infection.
And just generally, tuna is very dense in vitamins and minerals, something that we should frankly care a lot more about in our foods.
Robb Wolf says: “Maintaining adequate levels of selenium can protect us from mercury toxicity by binding to mercury as well as protecting us from oxidative damage. On top of that, the fish consumed by humans (except for the Mako shark and possibly some species of whales) contain more selenium than mercury. This makes it safe to get all the positive health aspects associated from eating fish 1-2 times per week.”
Mark Sisson says: “Tuna is tasty, especially the steaks, and it’s a decent source of omega-3s, but the mercury content can’t be ignored. Avoid if you are pregnant, nursing, or a small child, and don’t make tuna of any kind a daily staple. Look for troll and pole-caught tuna over longline-caught tuna, as the former tend to run smaller and accumulate fewer contaminants than the latter.”