Did you know that the availability of selenium regulates glutathione activity in the human body? No biggie! Glutathione is only one of our most important and potent antioxidants – meaning it combats free radicals and reduces oxidative stress.
Mercury is strongly attracted to selenium, and will bind with selenium, forming compounds that cannot be absorbed by the body, but will instead be excreted. Although this process renders mercury harmless, it also uses up selenium that may have otherwise been used for antioxidant roles in the body. So, good news if you have adequate selenium stores, or the fish you just ate contained more selenium than mercury (likely the case for all smaller ocean fish, but not so for larger, predatory species, like shark)….not so good news if you are selenium-deficient.
Remember how they told pregnant women to avoid eating fish, due to mercury exposure? We know that mercury can cross the placenta and cause brain damage (among other things) in the unborn child. But it turns out that ocean-caught fish are an abundant source of selenium that protects from the mercury found therein, and a deficiency of selenium during pregnancy can also cause brain damage in the developing fetus.
Fish that have a positive selenium : mercury ratio (more selenium than mercury) include halibut, sole, salmon, snapper, flounder and chunk light tuna [Ralston et al. 2008, 2016]
Given the above info, it is probably wise to increase selenium intake before and after removal of amalgam fillings.
Studies show that selenium is also protective against arsenic and cadmium poisoning, both through increased methylation activity, and via binding of the heavy metals, making them biologically inert, and able to be excreted from the body without interacting with (and damaging) cells [Zwolak, 2020].
Some soils are naturally low in selenium (Australia and New Zealand), and what selenium is left in the soil is not taken up by certain plants, in the presence of super-phosphate fertilisers.
The most bioavailable form of supplementation is a yeast-based product called Selenoexcell.