It’s common knowledge that there are minuscule amounts of mercury in fish. But it’s a fundamental rule of toxicology that the dose makes the poison. After all, drinking too much water can kill you.
So the bottom line is, how much fish is safe to eat? There’s a lot of noise surrounding this question, and it depends on who you ask. But thankfully, there’s now an app for that.
The HowMuchFish.com app is a handy seafood calculator that uses government data. And it turns out that you can practically eat a school of many kinds of fish and not have to be concerned about any potential harm.
A 150-pound person can eat 15 pounds of calamari, 7.5 pounds of salmon, or 28 cans of light tuna a week without worry. Meanwhile, a single can of tuna provides 248 percent of the body’s daily need of selenium, 87 percent of the daily protein need, and a 92 percent of the daily need for omega-3s.
We’ve all heard of the importance of omega-3s for heart health. But fish also provides benefits for developing fetuses. Scientists reported in the respected journal The Lancet in 2007 that mothers who consumed the most fish had children who did the best on IQ tests, and vice versa. (That’s why fish is known as “brain food.”) They concluded: “[A]dvice to limit seafood consumption could actually be detrimental.”
And just as importantly, there are absolutely zero cases of mercury poisoning due to commercially bought seafood in the medical literature. That is, unless you count Entourage star and drama queen Jeremy Piven, who backed out of a Broadway show in late 2008 claiming his blood mercury levels were several times too high after he followed a high-sushi diet.
As you might expect, Hollywood stars can’t be relied upon for credible medical advice. (Remember, Piven just played a doctor in Heat.) When “Good Morning America” had Piven on to tell his sob story, it also quoted a real expert, the director of toxicology at the UC Irvine Medical Center, who said: “It is very easy to have mercury levels 5-6 times the upper limit of normal by eating lots of fish, and this does not result in any objective evidence of mercury poisoning.”
Unfortunately, one Hollywood hack isn’t the only one pushing the “deadly fish” meme. Greenpeace is one of the more notorious offenders, publishing an “advisory” warning young children and women of childbearing age not to eat tuna and other fish.
These scare tactics have a profoundly negative effect on children from low-income families. Canned tuna is one of the cheapest sources of omega-3s, yet 4.4 million U.S. households earning $30,000 or less completely eliminated their purchases of canned tuna between 2000 and 2006. About 260,000 children were born in these households during that time. They missed out on a lot of omega-3-rich brain food.
Greenpeace says kids should avoid tuna. But legitimate science points in the other direction.