Comparison of the toxicity of selenium and selenium-enriched yeast The National Food and Drug Safety Commission (FDA) has established and published a “safe and effective dose” of selenium for human intake of 50-200 micrograms per day. The naturally occurring selenium that people consume is mainly selenoproteins such as selenomethionine and selenocysteine. Foods such as fish and flour contain a lot of selenium, especially high levels of organic selenium. Selenium-rich yeast has a high content of selenomethionine, and experiments have demonstrated that 70% of the selenium in selenium-rich yeast is in the form of selenomethionine. Studies evaluating the toxic effects of different forms of selenium have shown that zinc-rich yeast is less toxic than inorganic selenium such as sodium selenate and sodium selenite. An experiment with mice showed no toxicity after 14 days of administration of high doses of zinc-rich yeast (1.5 and 3.0 mg of organic selenium per kg body weight), a dose level much higher than the theoretical toxic dose level of inorganic selenium (Leiras, internal report). Another experiment with mice, comparing the toxicity of selenate and zinc-rich yeast, found zinc-rich yeast to be less toxic (Spallhloz and Raftery,1987). In mice fed a high dose of Zn-rich yeast with a concentration of selenium up to 16 ppm, no hepatotoxicity, cardiotoxicity or splenomegaly was observed after 8 weeks of feeding. In contrast, various signs of toxicity could be produced if the same dose of inorganic selenium was fed. The importance of selenium yeast in the diet Selenium is an essential trace element, and selenium-rich yeast is a natural dietary selenium that has been shown in clinical trials to increase selenium levels in humans. Selenium has been shown to be an antioxidant substance that is a major component of glutathione peroxidase, whose primary role is to inactivate free radicals. Selenium has an important role in the metabolic process of conversion of active thyroid hormone (T4) to inactive thyroid hormone (T3). Selenium can be involved in the detoxification of heavy metals, especially mercury, lead and cadmium. It has also been reported that selenium-enriched yeast can protect the body from radioactive damage, even after exposure to radiation. A study conducted in Finland on 200 lactating mothers supplemented with organic selenium (selenium-enriched yeast) and inorganic selenium, followed by a study on the effects of selenium on exclusively breastfed infants, found that a daily intake of 500-750 mg of selenium-enriched yeast by the mother was sufficient and safe to meet the needs of both the infant and the mother. When supplementing with selenium, supplementation with naturally occurring selenium in foods should be the first choice. Selenium-enriched yeast is produced in a finely controlled fermentation process that converts selenium into the same form as naturally occurring selenium in food. Reduced carcinogenicity: The trace element selenium is one of the key components of the glutathione peroxidase Glutathione Petoxidase in living organisms and is one of the main enzymes for the removal of free radicals free radicals in the body. Free radicals have generally been identified as one of the causes of the process by which animal cells become diseased and become cancerous. Organic selenium can help to reduce free radicals and thus reduce the chance of carcinogenesis. Hundreds of medical studies and large scale clinical trials have been reported in European and American literature since the 1960s. The benefits should not be disputed. Thyroid physiological function: In the early 1990s, it was also reported in the literature that selenium is an important component of the activating enzyme of the thyroid hormone T3, and that selenium deficiency can lead to a series of pathologies of thyroid insufficiency. Organic selenium and other toxic metals: Organic selenium has long been shown to combine with other toxic metals to form complexes in living organisms, so that these heavy metals no longer react with other components of the organism to cause harm. For example, mercury, lead and cadmium are neutralized by the reaction with organic selenium. Organoselenium and Radiation Recovery: Organoselenium products have been used in the rehabilitation of patients from the former Soviet nuclear power plant contamination in Russia and have shown to be effective in assisting recovery. It is thought that this may be related to its ability to stimulate thyroid activity. Human diseases caused by selenium deficiency: Recent medical findings have further revealed that insufficient selenium absorption predisposes the body to cardiovascular disease, arthritis, and cancer due to reduced immune function.