Selenium bioavailability: current knowledge and future research requirements

Abstract

Information on selenium bioavailability is required to derive dietary recommendations and to evaluate and improve the quality of food products. The need for robust data is particularly important in light of recent suggestions of potential health benefits associated with different intakes of selenium. The issue is not straightforward, however, because of large variations in the selenium content of foods (determined by a combination of geologic/environmental factors and selenium supplementation of fertilizers and animal feedstuffs) and the chemical forms of the element, which are absorbed and metabolized differently. Although most dietary selenium is absorbed efficiently, the retention of organic forms is higher than that of inorganic forms. There are also complications in the assessment and quantification of selenium species within foodstuffs. Often, extraction is only partial, and the process can alter the form or forms present in the food. Efforts to improve, standardize, and make more widely available techniques for species quantification are required. Similarly, reliable and sensitive functional biomarkers of selenium status are required, together with improvements in current biomarker methods. This requirement is particularly important for the assessment of bioavailability, because some functional biomarkers respond differently to the various selenium species. The effect of genotype adds a potential further dimension to the process of deriving bioavailability estimates and underlines the need for further research to facilitate the process of deriving dietary recommendations in the future.Am J Clin Nutr 2010;91(suppl):1484S-91S.

Selenium biochemistry and its role for human health

“…Almost all forms of Se, inorganic as well as organic, are readily absorbed with an overall efficiency close to be complete (70-90%) under normal physiological and intake conditions. 37 Selenite is an exception because its direct absorption does not exceed 60%. However, in the presence of reduced glutathione (GSH), as occurs in the gastrointestinal fluid, the absorption of selenite is increased up to quantitative proportions.…”

Meat nutritional composition and nutritive role in the human diet

“…Its content can range from 40 to 50 mcg/100 g of fresh meat. However, the bioavailability of selenium is quite variable though meat cuts have good bioavailability (Fairweather-tait, Collings, & Hurst, 2010).…”

The role of selenium in thyroid gland pathophysiology

“…Zgodnie z zaleceniami opublikowanymi przez Food and Nutrition Board of the National Academy of Science mężczyźni powinni spożywać 40-70 µg a kobiety 45-55 µg (w ciąży i w okresie karmienia 60-70 µg) selenu dziennie [5,6]. Jak wykazały badania populacyjne średnie dobowe spożycie selenu w krajach europejskich wynosi 20-70 µg/dobę [1,5,[7][8][9], a w Polsce 20-59 µg dziennie [10,11]. Z kolei według 30-dniowej obserwacji innych badaczy typowa dieta przeciętnego Amerykanina dostarcza codziennie od 90 do 168 µg tego pierwiastka [12].…”

“…Following the guidelines developed by the Food and Nutrition Board of the National Academy of Science, men should consume 40-70 µg and women 45-55 µg (60-70 µg during gestation and lactation periods) daily [5,6]. According to population studies, the mean daily intake of selenium at European countries is 20-70 µg [1,5,[7][8][9] and 20-59 µg in Poland [10,11]. In turn, following the 30-day observation of other researchers, a typical diet of an average American provides from 90 to 168 µg of this microelement daily [12].…”