Selenium supports a number of different selenium-dependent proteins that are important for our energy turnover, metabolism, immune defense, fertility, and antioxidant protection. Selenium also has a special affinity for mercury and is therefore able to bind to this heavy metal and counteract its harmful impact on the brain, the nervous system, and other tissues. Once selenium is bound to mercury, however, the different selenoproteins are no longer able to use it. We are all exposed to a certain amount of mercury and that may result in a borderline deficiency of selenium. The problem is that other factors weigh in such as selenium-depleted crops because of the lack of selenium in the European farmland. What is important to realize is that mercury toxicity is insidious and certain fish such as predatory fish and whales in the upper part of the food chain contain large concentrations of mercury. However, therapeutic doses of selenium can prevent the toxic effect of the heavy metal, according to a new review article published in Scientific Research.