Too much or too little? A review of the conundrum of selenium

Abstract

Chemical elements such as selenium, fluoride, iron, calcium and magnesium are essential to the human being, although some are toxic when absorbed in high doses. In this paper, the risks associated with insufficient and excessive intake of selenium in the diet are reviewed, focusing on drinking water. Two different approaches are used to derive recommended nutrient intakes (RNI) for adequate nutritional status and guideline values to prevent excessive exposure. The former is based on the daily intake which meets the nutrient requirements of 97.5% of the population. The latter is a value derivation based on an assumed daily per capita consumption at the individual level, a conservative approach used where there is any uncertainty and is related to a negligible risk to health at population level across life stages. There is an increasing need to develop a conceptual framework bringing together aspects of toxicity and essentiality especially for elements apparently exhibiting narrow or overlapping ranges between essentiality and toxicity and to provide guidance on the nature and severity of risks in order to better protect human.While there are a number of frameworks available, these generally only consider food. There is a need to include water, which can be a significant source in some circumstances.

Selenium status and cardiometabolic health: State of the evidence

“…While the primary emphasis of selenium research has been on evaluating the potential benefits of its antioxidant and anticancer effects, 5-9 recent findings from observational studies and randomized clinical trials have suggested an association between moderate to high selenium exposure and adverse cardiometabolic effects, at least in populations with adequate selenium intake such as the US. [86][87] Therefore, the apparently puzzling evidence [88][89] on the full range of effects, either beneficial or detrimental, of selenium exposure on chronic disease endpoints might be explained by the variability of selenium status and selenium dietary intakes across different countries and population subgroups. In this view, the association between selenium and cardio-metabolic outcomes is likely to be U-shaped with potential harm occurring at selenium levels both below and above the physiological range for optimal activity of selenoproteins.…”

A Comparison of Sulfate and Selenium Accumulation in Relation to the Expression of Sulfate Transporter Genes in Astragalus Species

“…Selenium (Se) is an essential element for human and animal health, but excess consumption may also be toxic, and the concentration range from trace element requirement to lethality is narrow (Ohlendorf et al, 1986;Läuchli, 1993;Spallholz, 1994;Arteel and Sies, 2001;El-Bayoumy, 2001;Tapiero et al, 2003;Schomburg et al, 2004;Gore et al, 2010;Fairweather-Tait et al, 2011). In animals, trace amounts of Se are required to form selenoenzymes, including a number of thioredoxin reductases and glutathione peroxidases.…”

The suppression of thymic stromal lymphopoietin expression by selenium

“…Chemical elements such as selenium, fluoride, iron, calcium and magnesium are essential to human beings even though some are toxic when absorbed in high doses (Gore et al 2010). Among them, Se has various beneficial effects such as antioxidant, antitumor, antiulcer, and anti-inflammatory effects (Rayman 2000;Duntas 2009;Bhattacharya et al 2011;Kim et al 2011).…”