Red Mountain Spa (Utah)
From 1956 to 1965 nearly 3000 residents of Minamata and Niigata Japan were sickened as a result of consuming fish harvested from high mercury contaminated waters. Since then, several studies of coastal societies were initiated in an attempt to link high mercury consumption (from fish) to disease, especially cognitive impairment in infants (as witnessed in Minamata). Disappointingly, most of this research produced scant or no support to the widespread belief of mercury in fish being a perpetrator of disease. Put into perspective, however, the people of Minamata consumed fish containing 40 ppm of mercury, unquestionably the result of 27 tons of industrial mercury waste being dumped into Minamata Bay. By comparison, most common fish (salmon, sole, etc.) contain a mere ¼ to ¾ ppm with a few predator fish (like shark) jumping up to 2-3 ppm. So it's conceivable that the lack of evidence (apart from tragic events like Minamata and Niigata) may simply be attributable to low, overall planetary consumption.

However, the puzzle appears to be more complex. Knowing that there are coastal tribes who depend entirely on seafood as their main food source, and recognizing that fish harvested from their local waters contains 6-7 ppm (high) just doesn't add up when screened against their near total lack of mercury toxicity, including neuropathology in children.

The biggest clue to solving the riddle may be found in the Faroe Islands where a higher incidence of suppressed cognition development among the fish-eating populace has been noted. Unlike other coastal societies, however, the Faroe residents consume high amounts of pilot whale - a fish containing only a scant amount of selenium. Studies of people who consume lots of high-selenium fish and little or no selenium-deplete seafood (such as the residents of the Seychelles Islands) show no negative mercury-related health effects.

The possible positive effect of selenium in reducing mercury toxicity is well-supported in physiology. Sometimes called a "mercury magnet", selenium has a particularly strong affinity for mercury and has the ability to sequester mercury molecules making them biologically inactive. Low bioavailability means less methyl mercury to bind to key brain receptor sites in the developing fetus, ultimately reducing the risk of neuropathology.

The selenium protection hypothesis becomes even stronger when noting the high selenium/mercury ratios in common seafood. In tuna, for instance, there are approximately 19 molecules of selenium for every molecule of mercury (for a ratio of 19). Other fish having equally impressive ratios include salmon-15, halibut-10, cod-8, Pollock-8, snapper-6, grouper-5, swordfish-5, etc. As expected, the ratio for the pilot whale is low, i.e. 0.3.

Fish has always been a good choice for those at risk for heart disease with as little as one serving per week reducing the risk by over 30%. And now that the long shadow of potential mercury poisoning has been lifted, it looks even more inviting.