https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(11)61452-9.pdf

Selenium and human health

In the genetic code, UGA serves as a stop signal and a selenocysteine codon, but no computational methods for identifying its coding function are available. Consequently, most selenoprotein genes are misannotated. We identified selenoprotein genes in sequenced mammalian genomes by methods that rely on identification of selenocysteine insertion RNA structures, the coding potential of UGA codons, and the presence of cysteine-containing homologs. The human selenoproteome consists of 25 selenoproteins.

/pdf/characterization-of-mammalian-selenoproteomes-296pbto9lm.pdf

Characterization of Mammalian Selenoproteomes

Biogeochemistry of the Human Environment.- The Biosphere.- Soils.- Waters.- Air.- Plants.- Humans.- Biogeochemistry of Trace Elements.- Trace Elements of Group 1 (Previously Group Ia).- Trace Elements of Group 2 (Previously Group IIa).- Trace Elements of Group 3 (Previously Group IIIb).- Trace Elements of Group 4 (Previously Group IVb).- Trace Elements of Group 5 (Previously Group Vb).- Trace Elements of Group 6 (Previously Group VIb).- Trace Elements of Group 7 (Previously Group VIIb).- Trace Elements of Group 8 (Previously Part of Group VIII).- Trace Elements of Group 9 (Previously Part of Group VIII).- Trace Elements of Group 10 (Previously Part of Group VIII).- Trace Elements of Group 11 (Previously Group Ib).- Trace Elements of Group 12 (Previously Group IIb).- Trace Elements of Group 13 (Previously Group IIIa).- Trace Elements of Group 14 (Previously Group IVa).- Trace Elements of Group 15 (Previously Group Va).- Trace Elements of Group 16 (Previously Group VIa).- Trace Elements of Group 17 (Previously Group VIIa).

/pdf/trace-elements-from-soil-to-human-gyujylwhl8.pdf

Trace Elements From Soil to Human

This review covers current knowledge of selenium in the environment, dietary intakes, metabolism and status, functions in the body, thyroid hormone metabolism, antioxidant defense systems and oxidative metabolism, and the immune system. Selenium toxicity and links between deficiency and Keshan disease and Kashin-Beck disease are described. The relationships between selenium intake/status and various health outcomes, in particular gastrointestinal and prostate cancer, cardiovascular disease, diabetes, and male fertility, are reviewed, and recent developments in genetics of selenoproteins are outlined. The rationale behind current dietary reference intakes of selenium is explained, and examples of differences between countries and/or expert bodies are given. Throughout the review, gaps in knowledge and research requirements are identified. More research is needed to improve our understanding of selenium metabolism and requirements for optimal health. Functions of the majority of the selenoproteins await characterization, the mechanism of absorption has yet to be identified, measures of status need to be developed, and effects of genotype on metabolism require further investigation. The relationships between selenium intake/status and health, or risk of disease, are complex but require elucidation to inform clinical practice, to refine dietary recommendations, and to develop effective public health policies.

Selenium in human health and disease.

Food systems need to produce enough of the essential trace element Se to provide regular adult intakes of at least 40 microg/d to support the maximal expression of the Se enzymes, and perhaps as much as 300 microg/d to reduce risks of cancer. Deprivation of Se is associated with impairments in antioxidant protection, redox regulation and energy production as consequences of suboptimal expression of one or more of the Se-containing enzymes. These impairments may not cause deficiency signs in the classical sense, but instead contribute to health problems caused by physiological and environmental oxidative stresses and infections. At the same time, supranutritional intakes of Se, i.e. intakes greater than those required for selenocysteine enzyme expression, appear to reduce cancer risk. The lower, nutritional, level is greater than the typical intakes of many people in several parts of the world, and few populations have intakes approaching the latter, supranutritional, level. Accordingly, low Se status is likely to contribute to morbidity and mortality due to infectious as well as chronic diseases, and increasing Se intakes in all parts of the world can be expected to reduce cancer rates.

/pdf/selenium-in-global-food-systems-23a5koo10v.pdf

Selenium in global food systems.

The essential trace mineral, selenium, is of fundamental importance to human health. As a constituent of selenoproteins, selenium has structural and enzymic roles, in the latter context being best-known as an antioxidant and catalyst for the production of active thyroid hormone. Selenium is needed for the proper functioning of the immune system, and appears to be a key nutrient in counteracting the development of virulence and inhibiting HIV progression to AIDS. It is required for sperm motility and may reduce the risk of miscarriage. Deficiency has been linked to adverse mood states. Findings have been equivocal in linking selenium to cardiovascular disease risk although other conditions involving oxidative stress and inflammation have shown benefits of a higher selenium status. An elevated selenium intake may be associated with reduced cancer risk. Large clinical trials are now planned to confirm or refute this hypothesis. In the context of these health effects, low or diminishing selenium status in some parts of the world, notably in some European countries, is giving cause for concern.

T. P. Lyons

Papers

The importance of selenium to human health.