Selenium in Foods

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Publisher Summary The chapter discusses the research on Selenium in foods, its chemical speciation, geographic variation and various other factors. Analytical methods for analysis of Se in foods include fluorometry, atomic absorption spectrophotometry, neutron activation analysis, proton-induced x-ray emission measurement, and double isotope dilution method. Selenium occurs in proteins as analogs of amino acids, in plants as selenomethoinine and in animals as selenocysteine. Geographic variation in selenium content of foods is discussed. The variations of the Se content are due to the geographical differences in the amount and availabilities of Se in soils. The Se content of foods of plant origin can vary within a particular geographic region according to specific climatic conditions such as plant growth, maturity at harvest and crop yield. The livestock diets reflect the Se status of locally produced feedstuffs and animal products. Se in liquid formula foods varies according to combination of ingredients used and Se content in those ingredients. Utilization of dietary Se is explained. It is the net result of physiological and metabolic processes that convert a portion of ingested food Se into metabolically active form, necessary for physiological function. Three approaches to evaluate the relative efficacy of known amounts of Se are discussed. The amount of Se in human diets is explained. Focus on further research should be to improve the characterization of Se in core foods, to understand the factors affecting the bioavailability of Se from meals and to understand the health hazards associated with low and high intake of Selenium.