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Antioxidants in human nutrition
Nemcová, Romana ; Hučko, Boris (advisor) ; Hroncová, Zuzana (referee)
The aim of this study was to show the importance of the antioxidants in human nutrition, their functioning and effects on human health. Special attention is recently paid to antioxidants due to their positive effects on the human body. Antioxidant activity is variable which evaluates the ability of the body to capture the free radicals, to prevent their occurrence or to convert them to unreactive or less reactive forms. Free radicals are formed in the human body as a byproduct of metabolism in the cells, where they play a positive role in immunity. On the other hand, their excessive production may be detrimental to the organism, they disrupt cell membranes, destroy DNA. Excessive formation of reactive oxygen and nitrogen free radicals arises oxidative stress. Oxidative stress significantly contributes to the development of various degenerative diseases and tumors, it causes DNA mutation and it damages macromolecules and tissues.
Human organism has developed its own antioxidant activity in the form of endogenous antioxidants which are produced by the body. Exogenous antioxidants are received from food and they are mainly of plant origin. The antioxidant enzymes (SOD, catalase, peroxidase), vitamins, carotenoids and phenolic compounds are the most important. Antioxidants perform important functions in the food industry, in which they prevent oxidation of fats and proteins, maintain the taste and colour of the food and also increase their durability.
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Meaning and resource of selenium in human nutrition
KRATOCHVÍLOVÁ, Zuzana
Bachelor's thesis concentrates on functions of selenium in human nutrition. Selenium is an essential trace element of importance to human health. Its availability depends on the concentration of selenium in the soil. The average income of selenium in the Czech population are usually 36 g/day per individuals. Excess or insufficient selenium intakes can result in adverse effects on human health. The most important sources of selenium in the diets of most people are meat, fish, eggs, milk, cereals and nuts. Selenium plays an important role in a number of metabolic functions including antioxidant systems, thyroid hormone metabolism, immune function and reproduction. Low selenium status are associated with increased risk of mortality, poor immune function, and cognitive decline, while high selenium status cause garlic breath, hair and nail loss, disorders of the nervous system and skink and poor dental health. Amount of selenium and its need changes during life. Recommended doses of selenium for women are 55 g/day and for men 70 g/day. Pregnant and lactating women require an average of 65-75 g selenium/day. Selenium deficiency in women causes problems with pregnancy, fetal malformations or postnatal complications. Newborn baby receives in breast milk about 10 g selenium/day. The recommended doses for children are in the range of 20-30 g selenium/day. The lack of selenium in seniors causes loss of muscle mass and strenght. Conversely sufficient doses of selenium can prevent the development of osteoporosis and various health complications. During sport aktivity, in the body there arise a large amount of free radicals and that is why it is necessary to suply the body of a sufficient amount of selenim, which helps prevent with its antioxidant effect oxidative damage of the muscles. The population exposed to low levels of selenium, the lack can be increased by use of dietary supplements with selenium.
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