What's So Bad About Tuna - Sweet Potato Chronicles - Sweet Potato Chronicles

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.


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