Mercury and the Magic of Selenium

Why Kanaloa fresh seafood is mercury safe

Throughout mankind’s several thousand year siege of Mother Nature she’s fought back in many novel ways, almost always brutal and overwhelming. The earth shakes, the seas rise, mountains blow apart and rain fire. Occasionally though, in an act of benevolence, she interjects a small drop of magic that works to set right just a bit of the damage caused by our carelessness and stupidity. Selenium is such a drop of magic. A trace metal we all depend on for survival (though in quantities measured in micro-grams) Selenium is an important anti-oxidant; part of the body’s anti-cancer arsenal helping to destroy free radicals and prevent cellular damage. It also helps regulate thyroid function and is vital to a healthy immune system. That’s all a very good thing, but it’s not the magic. The magic lies in Selenium’s special affinity for binding with Mercury.

Mercury is a highly poisonous, heavy metal that has been mined, refined, and used by humans for at least 3500 years. While the ancient Egyptians knew of its poisonous qualities (slaves and prisoners were used to mine it) it was nevertheless used throughout the industrial revolution and into the 1900s in industrial, commercial and scientific applications before its dangers were well understood. (A single 1950s Studebaker employed up to 40lbs of mercury in its construction). A traitorous servant of hatters, alchemists, and even medical doctors, notables as famous as Abraham Lincoln and Isaac Newton are thought to have suffered from mercury poisoning during portions of their life. Even now mercury remains in use for applications such as gold mining. The result of all this historical use of refined mercury is an unfortunate abundance of the toxic metal set loose in our environment.

Methyl mercury, the most toxic form, finds its way into human tissue almost entirely through the consumption of contaminated fish and other aquatic animals. Because of “bio-magnification”, with each successive prey species passing the mercury in its tissue up the food chain, contamination is most prevalent in large predator species residing at the top, such as tuna, sharks, or swordfish. Hence we are inundated with ubiquitous warnings about consuming such fish due to high mercury concentrations. Given mercury’s unquestionable toxicity such prohibition might seem prudent. 

Prudent, but highly inconvenient if you like fish, and want to take advantage of its numerous attendant healthful characteristics. Enter our magic Selenium. Ocean fish represent 16 of the 25 highest naturally occurring concentrations of selenium. You could rely on kelp, or molasses for your selenium fix, but ocean fish represent a far tastier source. But what about the mercury, you ask? Well, remember that “special binding affinity”? When ingested, selenium binds with mercury, segregating it, and rendering it incapable of binding with human organ tissue. The trick is simply to eat fish that contain more selenium than mercury. And the good news is almost ALL wild-caught ocean fish contain more selenium than mercury. (Pilot whales (not a fish) and some sharks, are notable exceptions. But unless you’re at dinner on the Faroese islands, Pilot whale is likely not on the menu.)

Think of Selenium like insurance. As long as you have enough coverage (more selenium than mercury), the negative effects of mercury ingestion are mitigated by your selenium policy. The amount of “coverage” you actually purchase is a function of the Selenium Health Benefit Value – the ratio between the amount of selenium to the amount of mercury in the fish. Those species with the highest SHBV (10 to 25 times as much selenium as mercury) are:

  1. Yellow fin
  2. Albacore
  3. Skipjack
  4. Mahi-Mahi
  5. Wahoo

Now who said Mother Nature is cruel? Here she is, happily cleaning up after our mess. Despite the best efforts of some to ruin a good thing, Mother Nature has stepped in to keep fish on the menu. Unless you’re pregnant, or still an infant (the fetus and infants are more susceptible to mercury poisoning), Mother Nature has provided you with a free pass to enjoy all the sustainably managed wild caught ocean fish you want. If you want your magic selenium delivered in the highest quality fresh fish available and you want to be certain that fish species is sustainably managed and taken in an environmentally responsible manner get, your fresh seafood, delivered overnight, from Kanaloa Seafood. Nobody provides fresher, higher quality, sustainably harvested seafood than Kanaloa. We fish the oceans of the world to bring you the finest sustainable seafood available.


  3. US Dept. of Agriculture – National Nutritional Data Base, Release 22, Nutrient Lists