What’s So Bad About Tuna

As I polished off my third can of tuna in as many days last week I thought to myself “self, three cans in one week, really?” I know you’re not really supposed to eat tuna that often, because of the mercury. I’ve heard everything from once a week to once a month. But as a vegetarian who is allergic to eggs, getting protein is hard y’all! So I put the “I know I shouldn’t but it tastes good and it’s easy” blinders on and fire up the can opener.

But I’m afraid I’m going to start glowing… or maybe I’m contributing to some horrible overfishing that’s wiping out the tuna population. So I did a little research. And now, join me, won’t you, while I destroy our illusions about yet another food. Tra la la.

Issue one: the mercury. It’s all about the food chain and since tuna are big fish, they eat a lot of smaller fish which adds up to higher mercury content. They’re also a fatty fish (nutritionally good) which is where mercury tends to be stored (bad). And why don’t we want a serving of mercury with our tuna salad (and to be fair to tuna, many other species of fish)? According to the Zero Mercury Working Group, the newest research is showing that even lower dietary levels than previously thought can impact brain and nervous system function. Of particular concern is the brain development in utero and of young children. And while we may get downright blasé when we’re bombarded with the minutiae of developmental stages, one researcher put the damage in a rather stark way. “Professor Philippe Grandjean, from the University of Southern Denmark and Harvard School of Public Health, (has) present(ed) new evidence on prenatal exposure to mercury in the womb. Dr. Grandjean’s results indicate that mercury exposure before birth can result in $18,000 in lost lifetime earning potential for each IQ point lost, which adds up to many billions of dollars per year on a global scale”.

While those kinds of numbers provide interesting context, of course it’s the real health effects we worry most about, for ourselves and our children. According to the National Resources Defence Council (NRDC), “even in low doses mercury may affect a child’s development, delaying walking and talking, shortening attention span and causing learning disabilities. In adults, mercury poisoning can adversely affect fertility and blood pressure regulation and can cause memory loss, tremors, vision loss and numbness of the fingers and toes. A growing body of evidence suggests that exposure to mercury may also lead to heart disease” (Source)

Issue two: overfishing. Yep, the NRDC says “Many of the most popular fish — like cod, snapper, and tuna — are dangerously depleted, yet continue to be overfished…(and) more than half of global fish populations are fully exploited and about one-third are overexploited or collapsed”.  The good news, they say, is that it’s not too late for governments to implement sensible fishing practices to replenish supplies and more stringent regulations around pollution. In the meantime, do we pass on the tuna? It’s a personal choice that must weigh convenience, nutrition and social responsibility. So yeah, easy. If you do still want to include tuna in your family’s diet, check out the tips at Sustainablog (here) and from Health Canada (here).

You know what’s not full of mercury OR overfished? French fries… discuss.