Biological Activity of Selenium and Its Impact on Human Health

Abstract

Selenium (Se) is a naturally occurring metalloid element essential to human and animal health in trace amounts but it is harmful in excess. Se plays a substantial role in the functioning of the human organism. It is incorporated into selenoproteins, thus supporting antioxidant defense systems. Selenoproteins participate in the metabolism of thyroid hormones, control reproductive functions and exert neuroprotective effects. Among the elements, Se has one of the narrowest ranges between dietary deficiency and toxic levels. Its level of toxicity may depend on chemical form, as inorganic and organic species have distinct biological properties. Over the last decades, optimization of population Se intake for the prevention of diseases related to Se deficiency or excess has been recognized as a pressing issue in modern healthcare worldwide. Low selenium status has been associated with an increased risk of mortality, poor immune function, cognitive decline, and thyroid dysfunction. On the other hand, Se concentrations slightly above its nutritional levels have been shown to have adverse effects on a broad spectrum of neurological functions and to increase the risk of type-2 diabetes. Comprehension of the selenium biochemical pathways under normal physiological conditions is therefore an important issue to elucidate its effect on human diseases. This review gives an overview of the role of Se in human health highlighting the effects of its deficiency and excess in the body. The biological activity of Se, mainly performed through selenoproteins, and its epigenetic effect is discussed. Moreover, a brief overview of selenium phytoremediation and rhizofiltration approaches is reported.

Selenium intake and multiple health-related outcomes: an umbrella review of meta-analyses

“…Two authors (PZW and BC) acquired the following data in an independent manner from qualified meta-analyses: (1) publication year, (2) the first author's name, (3) category of exposure (patterns of selenium intake), (4) healthy results, (5) number of included studies, (6) number of participants in each study, (7) study design (crosssectional, case-control, cohort, RCTs, and NRCTs), ( 8) type of comparisons (highest versus lowest, any versus never and increment or reduction of any dose of selenium intake), (9) Cochran' s Q test p value, (10) Egger' s test p value, (11) the estimated summary effect (SMD, standard mean difference; WMD, weighted mean difference; OR, odds ratio; RR, relative risk) and corresponding 95% confidence intervals (CIs), ( 12) I 2 statistic value, (13) effect model (random or fixed), and (14) follow-up time. The p value for nonlinearity was also extracted if a dose-response analysis was performed in a metaanalysis.…”

Nutrition and thyroid disease

“…The fact that about 30% of the global population is at risk of iodine deficiency disorders together with recent reports that low Se status has been associated with an increased risk of mortality, immune deficiency, cognitive decline, and thyroid dysfunction underlines the urgent need for implementation of a dietary strategy to counteract these critical deficits and protect human life from an array of diseases [8,50]. There is also a need to better define the role of certain other nutrients, such as magnesium, Vit.…”

The causal effects between selenium levels and the brain cortical structure: A two‐sample Mendelian randomization study

“…Se is also being explored as a potential therapeutic agent for Alzheimer's disease, multiple sclerosis, and stroke (Darvesh et al, 2010;Rajasekaran et al, 2008). Alternatively, it has been observed that elevated levels of Se, including inorganic Se compounds exceeding nutritional thresholds, can adversely affect various neurological functions and elevate the likelihood of developing type-2 diabetes (Genchi et al, 2023).…”