This is the second in a series of guest blog posts by Skipper Otto’s member and Registered Holistic Nutritionist, Melissa Evanson. Have seafood-related nutrition questions? Feel free to comment on this post or email us and Melissa will answer them here and on our Facebook page.
The health benefits of eating tuna have been widely touted; it’s a high-protein fish with an abundance of omega-3 fatty acids, vitamin D and selenium, a key trace mineral essential in supporting the immune system, brain function and reproductive health1. More on selenium in a bit; but we’ve all also heard that tuna contains mercury, a heavy metal with neurotoxic properties. Does that mean we should avoid Skipper Otto’s delicious rosemary tuna loin and tuna loin with coconut glaze recipes? Absolutely not!
Mercury levels in the environment have increased since the industrial revolution, primarily due to waste burning and coal combustion. And yes, fish can accumulate mercury in their muscle through absorption from surrounding water and from other fish they eat. As a fish gets larger and older, more toxins can accumulate over time.
Because of concerns over mercury in fish, B.C.’s Ministry of Health recommends daily limits for large, predatory fish species such as tuna, shark, marlin and swordfish2. But they also note that Albacore tuna products from Canada have no serving limits3. That’s right. No serving limits. Extensive and ongoing testing for mercury by the Canadian Inspection Food Agency has deemed Canadian North Pacific Albacore tuna (fresh, frozen and canned) “safe to eat” as mercury levels in these fish collected in Canadian waters is lower than in other species and stocks.
There are likely a few reasons for this. One is that B.C. Albacore are caught at a relatively young age (3-4 years) compared to the other listed species, like sharks and other tuna like bluefin, that have a longer lifespan to accumulate toxins. Another factor is habitat, or rather, where tuna spend their time. A study comparing mercury levels in Albacore from the North Pacific vs the Mediterranean showed a 10-fold increase in Mediterranean tuna4. This might be explained, in part, by the fact that the Mediterranean Sea is located over one of the richest natural reserves of mercury in the world and is also a semi-enclosed body of water in which toxic compounds can concentrate.
These factors are why selecting local B.C. Albacore tuna has significant advantages. Not all tuna are created equal!
But wait – low mercury levels in BC albacore tuna isn’t even the whole story! Let’s circle back to that selenium… Mercury toxicity can only occur when it’s in high enough concentrations to bind to selenium, preventing selenium from performing its vital role in the brain. Luckily for us Skipper Otto’s members, the BC fish we consume has significantly more selenium than mercury, unlike some international species/stocks of tuna, shark, swordfish, marlin, escolar and orange roughy.
The bottom line: There is no need to limit your Skipper Otto tuna orders due to mercury concerns. Your biggest concern when picking up your Skipper Otto tuna loins shouldn’t be about mercury, but about whether to sear it plain or sesame crusted!
Melissa Evanson, R.H.N.