Malignant tumors are diseases occurring in any population in the world, characterized by a high mortality [1]. In the developed countries are the second cause of death after cardiovascular diseases. Among the risk factors for many cancers, distinguished tastes bad habits. A new trend in academic research on the effects of inadequate supply of selenium in the diet at risk of developing cancer, in particular carcinoma of the colon, lung or prostate cancer. The role of selenium, looking also for prevention against cardiovascular events. Cardiovascular disease 50 years of age are the biggest threat to his countrymen. CSO data show since 1992 that the participation of these diseases in the total number of deaths decreased from 52% to 45.6% in 2012. Selenium deficiency also affects, for example, the development of thyroid disease. Autoimmune thyroiditis, hypothyroidism or crop neutral. Deiodinase are selenoenzymes, which play an essential role in the metabolism of thyroid hormones. Deiodinase, type 1, 2 is involved in the process dejodacji thyroxine [T4] for the active company in the form of 3,3 ', 5-triiodothyronine [T3] [34]. Selenium is a trace element was discovered in 1817 by Swedish chemist Berzelius. Until 1957 was considered, for the root of the toxic effects. Selenium is a trace element belonging to the micro [17,18,19]. As a building block and a redox active enzymes, the cytochrome is involved in metabolic processes in the cell. According to the National Academy of Sciences of the United States (NAS called. National Academy of Sciences), the average daily requirement for selenium (EAR- Estimated Average Requirements) and the recommended dose in the diet (RDA- Recommended Dietary Allowance) indicate selenium 45μg / day for adult women and adult man. Selenium is a trace element
