Microelement, -nutrient

Selenium is a vital microelement for people. It has dual properties. Selenium is an essential nutrient at low concentration levels and it becomes toxic at higher concentration levels. Deficiency of selenium results in weakness and hard diseases. Selenium is a building material of many hormones and ferments it neutralizes free radicals, radioactive radicals in organism. The range of selenium safety concentration in food and water is very narrow. The daily normal amount of human consumption of selenium is 10-20 p.g, maximum safe concentration of selenium in water is 5-10 p.g/1. It becomes toxic at 20-30 p.g and bigger content in different objects. 

The influence produced on the immune system by vitamins, macro- and microelements may result from the fact that many of these compounds function as activators of enzymes, mediators of immunological reactions, and compounds responsible for the transfer of information between cells. Deficiency of these nutrients can weaken the humoral and cellular response and, in many cases, the nonspecific response of the immune system. The following vitamins are believed to produce particular influence on the immune system A, B6, C, D, and E (Brock 1996, Mukhopadhyay et al. 2000, Pfahl and Chytil 1996, Semba 1998, Zhao et al. 1994) (Table 2.2.4). 

Both macro- and micro-elements are nutrients that are necessary for the growth and normal development of organisms and whose function cannot be taken on by any other element. They are therefore termed essential . For this reason, macro- and microelements are also called macro- or micro-nutrients. A division into essential and non-essential elements is not always appropriate, since there are numerous exceptions that become apparent when, for example, higher and lower plants are compared. We now know that calcium, boron and chlorine are not essential to some bacteria and fungi, and that sodium and silicon are not essential to higher plants (Marschner, 1983). 

Antioxidants (AO) are nutrient substances (vitamins, microelements, etc.), which human organisms require constantly. They serve to maintain a balance between free-radicals and AO forces. 

Trace elements, microelements elements required in very small quantities by living organisms. They act catalytically, or are components of catalytic systems. A elear distinction between T. e. and other mineral nutrients is not always possible, e.g. in the case of iron. A further classification into T. e. and ultratrace elements is sometimes used. 

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