Selenium⁻Fascinating Microelement, Properties and Sources in Food

Association between Selenium Status and Chronic Kidney Disease in Middle-Aged and Older Chinese Based on CHNS Data

Background: The association between selenium and chronic kidney disease (CKD) remains controversial. Population studies with large samples facilitate the reliability of conclusions. Objective: In this study, we aimed to describe the prevalence of a CKD association with selenium intake in middle-aged and older Chinese. Methods: Data for this study were obtained from the China Health and Nutrition Survey (CHNS). A total of 5381 participants (aged ≥ 45) with biochemical test data were included in the study. Logistic regression models were used to examine the association between diet selenium intake (quartile) and the prevalence of CKD. Results: A total of 942 (17.01%) participants had CKD. The prevalence of CKD was 23.33%, 20.32%, 14.98%, and 9.25% among participants with average selenium intakes of 21.5 ± 4.82, 33.1 ± 2.79, 43.8 ± 3.70, and 67.0 ± 13.97 µg/day, respectively. In the fully adjusted model (Model 3), across the quartiles of selenium intake, the ORs for the prevalence of CKD were 1.00, 1.09 (95% CI 0.69–1.73), 0.82 (95% CI 0.49–1.38), and 0.43 (95% CI 0.22–0.85). The protein intake had a certain diagnostic significance for the selenium intake. Conclusions: An adequate selenium intake may have a positive effect on CKD. The influence of individual weight and location on the effect of selenium on CKD needs to be further explored.

Antidepressant-Like Effect of a Selenoindolizine in Mice: In Vivo and In Silico Evidence for the Involvement of the Serotonergic 5-HT2A/C Receptors

The monoaminergic dysfunction plays a central role in major depressive disorder (MDD), a mental disturbance associated with constant feeling of sadness and lack of interest. The available treatments do not present a desirable efficacy and some of them provoke several adverse effects. In this context, organoselenium compounds and molecules containing the indolizine nucleus have demonstrated interesting pharmacological properties, including antidepressant-like effects. In this study, the antidepressant-like effect of 2-phenyl-1-(phenylselanyl)indolizine (SeI), a selenium-containing indolizine derivative, was investigated on the forced swimming test (FST) and on the tail suspension test (TST) in male Swiss mice. The involvement of the serotonergic system in this effect was also accessed. The selenium compound SeI (10-100 mg/kg, intragastrical (i.g.)) was administered 0.5 h before the behavioral tests, and it diminished the immobility on both FST and TST experiments, which is an indication of antidepressant-like effect. No changing in the locomotor motion was observed in the open-field test (OFT). The anti-immobility effect of SeI was not altered by the preadministration of the selective serotonergic receptor antagonists ondansetron (1 mg/kg, intraperitoneally (i.p.), antagonist of 5-HT₃ receptor) and WAY100635 (0.1 mg/kg, subcutaneous route (s.c.), antagonist of 5-HT_1A receptor). In contrast, the preadministration of ketanserin (1 mg/kg, i.p., antagonist of 5-HT_2A/C receptor) blocked this effect, demonstrating that the antidepressant-like effect of SeI involves 5-HT_2A/C. In addition, molecular docking studies showed a strong interaction between SeI and the receptors of 5-HT_2A and 5-HT_2C. The toxicological results demonstrated that SeI has low potential to cause adverse effects in mice. It was found that the antidepressant-like effect of SeI is related to modulation of the serotonergic system, and this selenium compound could be included in new treatment approaches for MDD.

Transcriptome analysis provides new insight into the distribution and transport of selenium and its associated metals in selenium-rich rice

Selenium is an essential trace element for humans and obtained from diary diets. The consumption of selenium-rich agricultural food is an efficient way to obtain selenium, but the quality and safety of selenium-rich agro-food are always affected by their associated heavy metals, even poses a potential threaten to human health. In this research, a sampling survey of heavy metals contents in selenium-rich rice was conducted, 182 sets of selenium-rich rice samples were collected from five selenium-rich rice-producing areas of China, and the accumulation of selenium and cadmium were found to be associated in rice and soil. Subsequently, a pot experiment was performed in the greenhouse via treating the soil samples with 12 different concentrations of selenium and heavy metals, and the contents of selenium and cadmium in rice grain were confirmed to be significantly associated. Moreover, transcriptome analysis revealed that the up-regulation of transporter-coding may promote the absorption of selenium and cadmium. The expression of antioxidant-coding genes and cadmium chelator transporter coding-genes was up-regulated to reduce the toxicity of cadmium. Meanwhile, the up-regulation of key genes of the ascorbic acid-glutathione metabolic pathway were responsible for the association between selenium and cadmium in Se-rich rice. Our work suggested the correlation between selenium and cadmium accumulation in selenium-rich rice, clarified their accumulation mechanism, provides a direction for the scientific production of selenium-rich agro-foods.

The Role and Mechanism of Essential Selenoproteins for Homeostasis

Selenium (Se) is one of the essential trace elements that plays a biological role in the body, mainly in the form of selenoproteins. Selenoproteins can be involved in the regulation of oxidative stress, endoplasmic reticulum (ER) stress, antioxidant defense, immune and inflammatory responses and other biological processes, including antioxidant, anti-inflammation, anti-apoptosis, the regulation of immune response and other functions. Over-loading or lack of Se causes certain damage to the body. Se deficiency can reduce the expression and activity of selenoproteins, disrupt the normal physiological function of cells and affect the body in antioxidant, immunity, toxin antagonism, signaling pathways and other aspects, thus causing different degrees of damage to the body. Se intake is mainly in the form of dietary supplements. Due to the important role of Se, people pay increasingly more attention to Se-enriched foods, which also lays a foundation for better research on the mechanism of selenoproteins in the future. In this paper, the synthesis and mechanism of selenoproteins, as well as the role and mechanism of selenoproteins in the regulation of diseases, are reviewed. Meanwhile, the future development of Se-enriched products is prospected, which is of great significance to further understand the role of Se.

Natural selenium stress influences the changes of antibiotic resistome in seleniferous forest soils

BACKGROUND

Metal(loid)s can promote the spread and enrichment of antibiotic resistance genes (ARGs) in the environment through a co-selection effect. However, it remains unclear whether exposure of microorganisms to varying concentrations of selenium (Se), an essential but potentially deleterious metal(loid) to living organisms, can influence the migration and distribution of ARGs in forest soils.

RESULTS

Precisely 235 ARGs conferring resistance to seven classes of antibiotics were detected along a Se gradient (0.06-20.65 mg kg^-1) across 24 forest soils. (flor)/(chlor)/(am)phenicol resistance genes were the most abundant in all samples. The total abundance of ARGs first increased and then decreased with an elevated available Se content threshold of 0.034 mg kg^-1 (P = 2E-05). A structural equation model revealed that the dominant mechanism through which Se indirectly influences the vertical migration of ARGs is by regulating the abundance of the bacterial community. In addition, the methylation of Se (mediated by tehB) and the repairing of DNA damages (mediated by ruvB and recG) were the dominant mechanisms involved in Se resistance in the forest soils. The co-occurrence network analysis revealed a significant correlated cluster between Se-resistance genes, MGEs and ARGs, suggesting the co-transfer potential. Lelliottia amnigena YTB01 isolated from the soil was able to tolerate 50 μg mL^-1 ampicillin and 1000 mg kg^-1 sodium selenite, and harbored both Se resistant genes and ARGs in the genome.

CONCLUSIONS

Our study demonstrated that the spread and enrichment of ARGs are enhanced under moderate Se pressure but inhibited under severe Se pressure in the forest soil (threshold at 0.034 mg kg^-1 available Se content). The data generated in this pilot study points to the potential health risk associated with Se contamination and its associated influence on ARGs distribution in soil.

The health benefits of selenium in food animals: a review

Selenium is an essential trace mineral important for the maintenance of homeostasis in animals and humans. It evinces a strong antioxidant, anti-inflammatory and potential antimicrobial capacity. Selenium biological function is primarily achieved by its presence in selenoproteins as a form of selenocysteine. Selenium deficiency may result in an array of health disorders, affecting many organs and systems; to prevent this, dietary supplementation, mainly in the forms of organic (i.e., selenomethionine and selenocysteine) inorganic (i.e., selenate and selenite) sources is used. In pigs as well as other food animals, dietary selenium supplementation has been used for improving growth performance, immune function, and meat quality. A substantial body of knowledge demonstrates that dietary selenium supplementation is positively associated with overall animal health especially due to its immunomodulatory activity and protection from oxidative damage. Selenium also possesses potential antiviral activity and this is achieved by protecting immune cells against oxidative damage and decreasing viral replication. In this review we endeavor to combine established and novel knowledge on the beneficial effects of dietary selenium supplementation, its antioxidant and immunomodulatory actions, and the putative antimicrobial effect thereof. Furthermore, our review demonstrates the gaps in knowledge pertaining to the use of selenium as an antiviral, underscoring the need for further in vivo and in vitro studies, particularly in pigs.

The Effects of Zinc and Selenium Supplementation on Body Composition and Thyroid Function in Individuals with Overweight or Obesity: A Systematic Review

People with obesity have been found to have lower zinc (Zn) and selenium (Se) circulatory levels and abnormal thyroid function than people with normal weight. Studies about the effects of Zn and Se supplementation on body composition and thyroid function of overweight-obese people showed inconsistent results. A systematic review of randomized controlled trials was conducted to determine the effects of Ζn supplementation, Se supplementation, and their combination on body composition and thyroid function of individuals with overweight or obesity. Databases of PubMed, ScienceDirect, and Cochrane, were searched from inception to February 27, 2022, to identify relevant articles. For the assessment of the methodological quality of the studies, the Jadad scale was used. After screening the articles, thirteen studies were finally included and were analyzed using the strength of the evidence approach. Regarding the effectiveness of Zn supplementation on body composition, moderate evidence was found, while the effects of Se were found to be mixed. Zn supplementation was found to affect the thyroid function of people with overweight or obesity by increasing their free triiodothyronine (FT3) levels. However, this result is based only on one study among hypothyroid patients. At this point, the effectiveness of Zn, Se, and their combination, on the body composition and the thyroid function of people with overweight or obesity cannot safely be determined because of the controversial results, small number, and the limitations of the identified studies. The results of this systematic review must be interpreted with caution due to the limitations detected.

The Role of Selenium Nanoparticles in Agriculture and Food Technology

Selenium (Se) is an essential micronutrient for diverse organisms such as mammals, bacteria, some insects and nematodes, archaea, and algae, as it is involved in a large number of physiological and metabolic processes and is part of approximately 25 selenoproteins in mammals. In plants, Se has no essential metabolic role, high concentrations of inorganic Se can lead to the formation of Se-amino acids, and its incorporation into selenoproteins can generate toxicity. Conversely, low doses of Se can trigger a variety of beneficial effects as an antioxidant, antimicrobial, or stress-modulating agent without being an essential element. Therefore, Se can generate toxicity depending on the dose and the chemical form in which it is supplied. Selenium nanoparticles (SeNPs) have emerged as an approach to reduce this negative effect and improve its biological properties. In turn, SeNPs have a wide range of potential advantages, making them an alternative for areas such as agriculture and food technology. This review focuses on the use of SeNPs and their different applications as antimicrobial agents, growth promoters, crop biofortification, and nutraceuticals in agriculture. In addition, the utilization of SeNPs in the generation of packaging with antioxidant and antimicrobial traits and Se enrichment of animal source foods for human consumption as part of food technology is addressed. Additionally, possible action mechanisms and potential adverse effects are discussed. The concentration, size, and synthesis method of SeNPs are determining factors of their biological properties.

Mediterranean-Type Diets as a Protective Factor for Asthma and Atopy

We are currently riding the second wave of the allergy epidemic, which is ongoing in affluent societies, but now also affecting developing countries. This increase in the prevalence of atopy/asthma in the Western world has coincided with a rapid improvement in living conditions and radical changes in lifestyle, suggesting that this upward trend in allergic manifestations may be associated with cultural and environmental factors. Diet is a prominent environmental exposure that has undergone major changes, with a substantial increase in the consumption of processed foods, all across the globe. On this basis, the potential effects of dietary habits on atopy and asthma have been researched rigorously, but even with a considerable body of evidence, clear associations are far from established. Many factors converge to obscure the potential relationship, including methodological, pathophysiological and cultural differences. To date, the most commonly researched, and highly promising, candidate for exerting a protective effect is the so-called Mediterranean diet (MedDi). This dietary pattern has been the subject of investigation since the mid twentieth century, and the evidence regarding its beneficial health effects is overwhelming, although data on a correlation between MedDi and the incidence and severity of asthma and atopy are inconclusive. As the prevalence of asthma appears to be lower in some Mediterranean populations, it can be speculated that the MedDi dietary pattern could indeed have a place in a preventive strategy for asthma/atopy. This is a review of the current evidence of the associations between the constituents of the MedDi and asthma/atopy, with emphasis on the pathophysiological links between MedDi and disease outcomes and the research pitfalls and methodological caveats which may hinder identification of causality. MedDi, as a dietary pattern, rather than short-term supplementation or excessive focus on single nutrient effects, may be a rational option for preventive intervention against atopy and asthma.

Hyperglycemia and Loss of Redox Homeostasis in COVID-19 Patients

The infection with SARS-CoV-2 impairs the glucose−insulin axis and this contributes to oxidative (OS) and nitrosative (NSS) stress. Here, we evaluated changes in glucose metabolism that could promote the loss of redox homeostasis in COVID-19 patients. This was comparative cohort and analytical study that compared COVID-19 patients and healthy subjects. The study population consisted of 61 COVID-19 patients with and without comorbidities and 25 healthy subjects (HS). In all subjects the plasma glucose, insulin, 8-isoprostane, Vitamin D, H2S and 3-nitrotyrosine were determined by ELISA. The nitrites (NO2−), lipid-peroxidation (LPO), total-antioxidant-capacity (TAC), thiols, glutathione (GSH) and selenium (Se) were determined by spectrophotometry. The glucose, insulin and HOMA-IR (p < 0.001), 8-isoprostanes, 3-nitrotyrosine (p < 0.001) and LPO were increased (p = 0.02) while Vitamin D (p = 0.01), H2S, thiols, TAC, GSH and Se (p < 0.001) decreased in COVID-19 patients in comparison to HS. The SARS-CoV-2 infection resulted in alterations in the glucose−insulin axis that led to hyperglycemia, hyperinsulinemia and IR in patients with and without comorbidities. These alterations increase OS and NSS reflected in increases or decreases in some oxidative markers in plasma with major impact or fatal consequences in patients that course with metabolic syndrome. Moreover, subjects without comorbidities could have long-term alterations in the redox homeostasis after infection.

Functional food: complementary to fight against COVID-19

Background

The novel coronavirus has embarked on a global pandemic and severe mortality with limited access for its treatments and medications. For the lack of time, research, and enough efficacy, most vaccines are underdeveloped or unreachable to society. However, many recent studies suggest various alternative, complementary remedies for COVID-19, which are functional foods. This review provides an overview of how functional foods can play a great role through modulating the host immune system, generating antiviral activities, and synthesizing biologically active agents effective against the coronavirus.

Main body

This review article summarizes the natural defense mechanisms in tackling SARS-CoV-2 alongside conventional therapeutic options and their corresponding harmful side effects. By analyzing bioactive components of functional foods, we have outlined its different contributions to human health and its potential immunomodulatory and antiviral properties that can enhance resistivity to viral infection. Moreover, we have provided a myriad of accessible and cost-effective functional foods that could be further investigated to target specific key symptoms of COVID-19 infections. Finally, we have found various functional foods with potent bioactive compounds that can inhibit or prevent COVID-19 infections and disease progression.

Short conclusion

Numerous functional foods can help the body fight COVID-19 through several mechanisms such as the reduced release of pro-inflammatory cytokines, reduced expression of ACE2 receptors in cells, and inhibiting essential enzymes in SARS-CoV-2.

Activation of the GPX4/TLR4 Signaling Pathway Participates in the Alleviation of Selenium Yeast on Deltamethrin-Provoked Cerebrum Injury in Quails

Deltamethrin (DLM) is a member of pyrethroid pesticide widely applied for agriculture and aquaculture, and its residue in the environment seriously threatens the bio-safety. The cerebrum might be vulnerable to pesticide-triggered oxidative stress. However, there is no specific antidote for treating DLM-triggered cerebral injury. Selenium (Se) is an essential trace element functionally forming selenoprotein glutathione peroxidase (GPX) in antioxidant defense. Se yeast (SY) is a common and effective organic form of Se supplement with high selenomethionine content. Accordingly, this study focused on investigating the therapeutic potential of SY on DLM-induced cerebral injury in quails after chronically exposing to DLM and exploring the underlying mechanisms. Quails were treated with/without SY (0.4 mg kg^-1 SY added in standard diet) in the presence/absence of DLM (45 mg kg^-1 body weight intragastrically) for 12 weeks. The results showed SY supplementation ameliorated DLM-induced cerebral toxicity. Concretely, SY elevated the content of Se and increased GPX4 level in DLM-treated quail cerebrum. Furthermore, SY enhanced antioxidant defense system by upregulating nuclear factor-erythroid-2-related factor 2 (Nrf2) associated members. Inversely, SY diminished the changes of apoptosis- and inflammation-associated proteins and genes including toll-like receptor 4 (TLR4). Collectively, our results suggest that dietary SY protects against DLM-induced cerebral toxicity in quails via positively regulating the GPX4/TLR4 signaling pathway. GPX4 may be a potential therapeutic target for insecticide-induced biotoxicity.

Effects of Selenium Nanoparticles on Preventing Patulin-Induced Liver, Kidney and Gastrointestinal Damage

Patulin (PAT) is a toxic fungal metabolite, and oxidative damage was proved to be its important toxicity mechanism. Selenium nanoparticles (SeNPs) were prepared by reducing sodium selenite with chitosan as a stabilizer and used for preventing PAT-induced liver, kidney and gastrointestinal damage. SeNPs have good dispersibility, in vitro antioxidant activity, and are much less cytotoxic than sodium selenite. Cell culture studies indicated that SeNPs can effectively alleviate PAT-induced excessive production of intracellular ROS, the decline of glutathione peroxidase activity, and the suppression of cell viability. Evaluation of serum biochemical parameters, histopathology, oxidative stress biomarkers and activities of antioxidant enzymes in a mouse model showed that pre-treatment with SeNPs (2 mg Se/kg body weight) could ameliorate PAT-induced oxidative damage to the liver and kidneys of mice, but PAT-induced gastrointestinal oxidative damage and barrier dysfunction were not recovered by SeNPs, possibly because the toxin doses suffered by the gastrointestinal as the first exposed tissues exceeded the regulatory capacity of SeNPs. These results suggested that a combination of other strategies may be required to completely block PAT toxicity.

A Comprehensive Review on Selenium and Its Effects on Human Health and Distribution in Middle Eastern Countries

Selenium (Se) is an important microelement with numerous positive effects on human health and diseases. It is important to specify that the status and consumption of Se are for a specific community as the levels of Se are extremely unpredictable between different populations and regions. Our existing paper was based on the impacts of Se on human health and disease along with data on the Se levels in Middle Eastern countries. Overall, the findings of this comprehensive review show that the consumption and levels of Se are inadequate in Middle Eastern nations. Such findings, together with the growing awareness of the importance of Se to general health, require further work primarily on creating an acceptable range of blood Se concentration or other measures to determine optimal Se consumption and, consequently, to guarantee adequate Se supplementation in populations at high risk of low Se intake.

Provision of Small-Quantity Lipid-Based Nutrient Supplements Increases Plasma Selenium Concentration in Pregnant Women in Malawi: A Secondary Outcome of a Randomized Controlled Trial

Background

Pregnant women in Malawi are at risk of selenium deficiency, which can have adverse effects on pregnancy outcomes. Interventions for improving selenium status are needed.

Objectives

To assess the effect of provision of small-quantity lipid-based nutrient supplements (SQ-LNSs) to Malawian women during pregnancy on their plasma selenium concentrations at 36 wk of gestation.

Methods

Pregnant women (≤20 wk of gestation) were randomly assigned to receive daily either: 1) iron and folic acid (IFA); 2) multiple micronutrients (MMN; 130 µg selenium per capsule); or 3) SQ-LNS (130 µg selenium/20 g). Plasma selenium concentrations were measured by inductively coupled plasma mass spectrometry at baseline and after ≥16 wk of intervention (at 36 wk of gestation) and compared by intervention group.

Results

At 36 wk of gestation, median (quartile 1, quartile 3) plasma selenium concentrations (micromoles per liter) were 0.96 (0.73, 1.23), 0.94 (0.78, 1.18), and 1.01 (0.85, 1.28) in the IFA, MMN, and SQ-LNS groups, respectively. Geometric mean (GM) plasma selenium concentration was 5.4% (95% CI: 1.8%, 9.0%) higher in the SQ-LNS group than in the MMN group and tended to be higher than in the IFA group (+4.2%; 95% CI: 1.0%, 7.8%). The prevalence of adjusted plasma selenium concentrations <1 µmol/L was 55.1%, 57.8%, and 47.3% in the IFA, MMN, and SQ-LNS groups, respectively; it was lower in the SQ-LNS group than in the MMN group, OR = 0.44 (95% CI: 0.24, 0.83), and tended to be lower than in the IFA group, OR = 0.54 (95% CI: 0.29, 1.03). There was a significant interaction between baseline plasma selenium concentration and intervention group (P = 0.003). In the lowest tertile of baseline selenium concentrations, GM plasma selenium concentration was higher, and the prevalence of low values was lower in the SQ-LNS group compared with the MMN and IFA groups at 36 wk of gestation (P ≤ 0.007).

Conclusions

Provision of SQ-LNS containing selenium to pregnant women can be an effective strategy for improving their selenium status.This trial was registered at clinicaltrials.gov (identifier: NCT01239693).

Effect of Brazil Nuts on Selenium Status, Blood Lipids, and Biomarkers of Oxidative Stress and Inflammation: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Tree nuts, including Brazil nuts, have been hypothesized to impact cardiovascular health through the modulation of oxidative stress and inflammation. Nonetheless, a quantitative analysis of these effects has not been performed. Therefore, the aim of this study was to systematically revise and quantify the effect of Brazil nut intervention on selenium status, blood lipids, and biomarkers of oxidative stress and inflammation using a meta-analytical approach. To meet the goals of this study, a systematic search of PubMed, EMBASE, and Web of Science databases of published randomised clinical trials reporting on dietary interventions with Brazil nuts and their effects on selenium status, blood lipids, and markers of oxidative stress and inflammation was performed. Eight articles were included for systematic review and meta-analysis. Based on the conducted analysis, a significant positive effect of Brazil nuts on selenium blood concentration (SMD = 6.93, 95% CI: 3.99; 9.87) was found. Additionally, a positive effect of Brazil nut intervention on glutathione peroxidase activity (SMD = 0.53, 95% CI: 0.07; 0.99) was observed. However, no significant results were found when considering blood lipid levels, including results for total cholesterol (SMD = −0.22, 95% CI: −0.57; 0.14), HDL cholesterol (SMD = −0.04, 95% CI: −0.28; 0.19) and LDL cholesterol (SMD = −0.15; 95% CI: −0.43; 0.13). In conclusion, the findings from this study suggest that Brazil nut consumption improves selenium status and exerts antioxidant effects, which could be considered a potential pathway for the prevention of metabolic disorders related to altered blood lipid profiles. However, further studies are needed to elucidate the effect of Brazil nuts toward blood lipid profile, also preferably controlling for other biomarkers.

Evaluating the effect of selenium on spatial memory impairment induced by sleep deprivation

Sleep deprivation (SD) impairs memory due to disturbing oxidative stress parameters. Selenium is a main component of several antioxidant enzymes and provides a neuroprotective effect. The present study aimed to investigate the potential neuroprotective effect of chronic selenium administration on cognitive impairments induced by chronic SD. Adult male Wister rats were randomly assigned into five groups (n = 12/group). The SD was induced in rats using modified multiple platform model. Selenium (6 µg/kg of animal's body weight) was administered to rats via oral gavage for 6 weeks. The spatial learning and memory were assessed using the radial arm water maze (RAWM). Moreover, we measured the levels of reduced glutathione (GSH), oxidized glutathione (GSSG) and GSH/GSSG, catalase, glutathione peroxidase (GPx), superoxide dismutase (SOD), thiobarbituric acid reactive substances (TBARS) and brain derived neurotrophic factor (BDNF) in the hippocampus. The results indicate that short- and long-term memory were impaired by chronic sleep deprivation (P < 0.05), while selenium administration prevented this effect. Moreover, selenium normalized antioxidants activities which were reduced by SD such as: catalase (P < 0.05), and SOD (P < 0.05), and significantly enhanced the ratio of GSH/GSSG in sleep-deprived rats (P < 0.05), without significant alteration of BDNF (P > 0.05), GSH (P > 0.05), or TBARS levels (P > 0.05). In conclusion, chronic SD induced memory impairment, and chronic treatment with selenium prevented this impairment by normalizing antioxidant enzymes activities in the hippocampus.

The Effects of Selenium on Bone Health: From Element to Therapeutics

Osteoporosis, characterized by low bone mass and a disruption of bone microarchitecture, is traditionally treated using drugs or lifestyle modifications. Recently, several preclinical and clinical studies have investigated the effects of selenium on bone health, although the results are controversial. Selenium, an important trace element, is required for selenoprotein synthesis and acts crucially for proper growth and skeletal development. However, the intake of an optimum amount of selenium is critical, as both selenium deficiency and toxicity are hazardous for health. In this review, we have systematically analyzed the existing literature in this field to determine whether dietary or serum selenium concentrations are associated with bone health. In addition, the mode of administration of selenium as a supplement for treating bone disease is important. We have also highlighted the importance of using green-synthesized selenium nanoparticles as therapeutics for bone disease. Novel nanobiotechnology will be a bridgehead for clinical applications of trace elements and natural products.

Association of selenium, zinc and copper concentrations during pregnancy with birth weight: A systematic review and meta-analysis

BACKGROUND

Normal fetal growth is associated with maternal nutrition. Trace elements play important roles in fetus growth. This review aims to provide a summary of the literature evaluating the relation between selenium, zinc and copper levels during pregnancy with birth weight.

METHOD

A systematic literature search was conducted in Medline database (PubMed), Scopus, Web of science and Google scholar up to September 2020. Fifty observational studies were included in the final analyses. The desired pooled effect size was considered as standardized mean differences with 95 % CI or correlation. Cochran's Q statistic was used to test the heterogeneity between the included studies (I²).

RESULT

A significant differences were found between pooled standardized mean differences (SMD) of umbilical cord blood copper levels in small-for-gestational age birth weight (SGA) and appropriate-for-gestational age birth weight (AGA) (SMD: 0.34 μg/L, 95 % CI: 0.13 to 0.56). There was a significant pooled correlation between umbilical cord blood selenium concentrations and birth weight (r: 0.08, 95 % CI: 0.01 to 0.16). A significant pooled correlation was found between umbilical cord blood zinc concentrations and birth weight (r: 0.09, 95 % CI: 0.04 to 0.15), with significant heterogeneity (I² % = 0.63). There was significant positive association between maternal blood zinc concentrations and birth weight.

CONCLUSION

Findings showed the association of trace elements including selenium, zinc and copper during pregnancy with birth weight. There was significant correlation between umbilical cord and maternal blood selenium and zinc levels with birth weight. The umbilical cord blood copper levels in SGA birth weight was higher than copper levels in AGA birth weight.

The Role of Methyl Donors of the Methionine Cycle in Gastrointestinal Infection and Inflammation

Vitamin deficiency is well known to contribute to disease development in both humans and other animals. Nonetheless, truly understanding the role of vitamins in human biology requires more than identifying their deficiencies. Discerning the mechanisms by which vitamins participate in health is necessary to assess risk factors, diagnostics, and treatment options for deficiency in a clinical setting. For researchers, the absence of a vitamin may be used as a tool to understand the importance of the metabolic pathways in which it participates. This review aims to explore the current understanding of the complex relationship between the methyl donating vitamins folate and cobalamin (B12), the universal methyl donor S-adenosyl-L-methionine (SAM), and inflammatory processes in human disease. First, it outlines the process of single-carbon metabolism in the generation of first methionine and subsequently SAM. Following this, established relationships between folate, B12, and SAM in varying bodily tissues are discussed, with special attention given to their effects on gut inflammation.

Selenotranscriptome Network in Non-alcoholic Fatty Liver Disease

Observational studies indicate that selenium may contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Transcriptomic exploration of the aetiology and progression of NAFLD may offer insight into the role selenium plays in this disease. This study compared gene expression levels of known selenoprotein pathways between individuals with a healthy liver to those with NAFLD. Publicly available gene expression databases were searched for studies that measured global gene expression in liver samples from patients with steatosis and non-alcoholic steatohepatitis (NASH) and healthy controls (with [HOC] or without [HC] obesity). A subset of five selenoprotein-related pathways (164 genes) were assessed in the four datasets included in this analysis. The gene TXNRD3 was less expressed in both disease groups when compared with HOC. SCLY and SELENOO were less expressed in NASH when compared with HC. SELENOM, DIO1, GPX2, and GPX3 were highly expressed in NASH when compared to HOC. Disease groups had lower expression of iron-associated transporters and higher expression of ferritin-encoding sub-units, consistent with dysregulation of iron metabolism often observed in NAFLD. Our bioinformatics analysis suggests that the NAFLD liver may have lower selenium levels than a disease-free liver, which may be associated with a disrupted iron metabolism. Our findings indicate that gene expression variation may be associated with the progressive risk of NAFLD.

Selenomethionine modulates insulin secretion in the MIN6-K8 mouse insulinoma cell line

Selenium is an essential trace element of interest for its potential role in glucose homeostasis. The present study investigated the impact of selenium supplementation as selenomethionine (SeMet) on insulin secretion in MIN6-K8 cells, a pancreatic β-cell model. We found that SeMet enhanced percent glucose-induced insulin secretion, while also increasing tolbutamide- and KCl-induced percent insulin secretion. RNA-sequencing showed that SeMet supplementation altered expression of several selenoproteins, including glutathione peroxidase 3 (Gpx3) and selenoprotein P (SelP). Targeted knockdown of Gpx3 increased both percent and total insulin release, while SelP knockdown increased insulin content and insulin release. Collectively, these studies support a putative role for selenium and selenoproteins in the regulation of insulin secretion, glucose homeostasis, and diabetes risk.

The Effect of Organoselenium Compounds on Histone Deacetylase Inhibition and Their Potential for Cancer Therapy

Genetic and epigenetic changes alter gene expression, contributing to cancer. Epigenetic changes in cancer arise from alterations in DNA and histone modifications that lead to tumour suppressor gene silencing and the activation of oncogenes. The acetylation status of histones and non-histone proteins are determined by the histone deacetylases and histone acetyltransferases that control gene transcription. Organoselenium compounds have become promising contenders in cancer therapeutics. Apart from their anti-oxidative effects, several natural and synthetic organoselenium compounds and metabolites act as histone deacetylase inhibitors, which influence the acetylation status of histones and non-histone proteins, altering gene transcription. This review aims to summarise the effect of natural and synthetic organoselenium compounds on histone and non-histone protein acetylation/deacetylation in cancer therapy.

Sex-dimorphic distribution and anti-oxidative effects of selenomethionine and Se-methylselenocysteine supplementation

Selenium (Se) is a vital trace element in human beings and is essential for protection against oxidative stress. This study aimed to investigate the accumulation and antioxidant effects of two organic seleniums, L-selenomethionine (SM) and L-Se-methylselenocysteine (SMC), through in vivo and in vitro experiments. L02 cells were pretreated with 10 nM SM or SMC for 24 h, followed by exposure to 100 nM of H₂O₂. Cell viability, apoptosis, and antioxidant capacity were detected to evaluate SM and SMC's protective effect. Organic selenium (SM and SMC) and inorganic selenium (sodium selenite, SS) were compared in terms of their in vivo accumulation and antioxidant capacity when supplemented daily and subsequently deprived in SD rats. Our results show that SM or SMC pre-treatment could significantly prevent elevated apoptosis and declined antioxidant ability. We found that organic Se supplementation resulted in higher Se accumulation than inorganic Se in the liver and kidney. The antioxidant capacity of liver and kidney tissues from rats fed with either organic selenium was significantly improved and was higher than that of SS. In summary, this study suggests that organic selenium supplements are more effective in facilitating Se accumulation in liver and kidney, enhancing antioxidant capacities, thereby protecting cells from oxidative stress. PRACTICAL APPLICATION: This study compared the antioxidant capacity of sodium selenite, L-selenomethionine, and L-Se-methylselenocysteine in vitro and in vivo. The results showed that organic selenium has a stronger antioxidant capacity and that significant differences exist in its absorption and conversion in male and female rats. Our results provide theoretical guidance for dietary supplementation of selenium.

Associations of Habitual Mineral Intake with New-Onset Prediabetes/Diabetes after Acute Pancreatitis

Associations between habitual dietary intake of minerals and glucose metabolism have been extensively studied in relation to metabolic disorders. However, similar research has yet to be conducted in individuals after acute pancreatitis (AP). The main aim was to investigate the associations between habitual intake of 13 minerals and glycaemic status: new-onset prediabetes/diabetes after AP (NODAP), pre-existing prediabetes/type 2 diabetes (T2DM), and normoglycaemia after AP (NAP). Associations between the dietary intake of minerals and markers of glucose metabolism (glycated haemoglobin and fasting plasma glucose) were also studied. The EPIC-Norfolk food frequency questionnaire was used in a cross-sectional fashion to determine the habitual intake of 13 dietary minerals. ANCOVA as well as multiple linear regression analyses were conducted and five statistical models were built to adjust for covariates. The study included 106 individuals after AP. In the NODAP group, intake of 4 minerals was significantly less when compared with the NAP group: iron (B = -0.076, p = 0.013), nitrogen (B = -0.066, p = 0.003), phosphorous (B = -0.046, p = 0.006), and zinc (B = -0.078, p = 0.001). Glycated haemoglobin was significantly associated with iodine intake (B = 17.763, p = 0.032) and manganese intake (B = -17.147, p = 0.003) in the NODAP group. Fasting plasma glucose was significantly associated with manganese intake (B = -2.436, p = 0.027) in the NODAP group. Habitual intake of minerals differs between individuals with NODAP, T2DM, and NAP. Prospective longitudinal studies and randomised controlled trials are now warranted to further investigate the associations between mineral intake and NODAP.

Trace Element Selenium Effectively Alleviates Intestinal Diseases

Selenium (Se) is an essential trace element in the body. It is mainly used in the body in the form of selenoproteins and has a variety of biological functions. Intestinal diseases caused by chronic inflammation are among the most important threats to human health, and there is no complete cure at present. Due to its excellent antioxidant function, Se has been proven to be effective in alleviating intestinal diseases such as inflammatory bowel diseases (IBDs). Therefore, this paper introduces the role of Se and selenoproteins in the intestinal tract and the mechanism of their involvement in the mediation of intestinal diseases. In addition, it introduces the advantages and disadvantages of nano-Se as a new Se preparation and traditional Se supplement in the prevention and treatment of intestinal diseases, so as to provide a reference for the further exploration of the interaction between selenium and intestinal health.

Maternal malnutrition and anaemia in India: dysregulations leading to the 'thin-fat' phenotype in newborns

Maternal and child malnutrition and anaemia remain the leading factors for health loss in India. Low birth weight (LBW) offspring of women suffering from chronic malnutrition and anaemia often exhibit insulin resistance and infantile stunting and wasting, together with increased risk of developing cardiometabolic disorders in adulthood. The resulting self-perpetuating and highly multifactorial disease burden cannot be remedied through uniform dietary recommendations alone. To inform approaches likely to alleviate this disease burden, we implemented a systems-analytical approach that had already proven its efficacy in multiple published studies. We utilised previously published qualitative and quantitative analytical results of rural and urban field studies addressing maternal and infantile metabolic and nutritional parameters to precisely define the range of pathological phenotypes encountered and their individual biological characteristics. These characteristics were then integrated, via extensive literature searches, into metabolic and physiological mechanisms to identify the maternal and foetal metabolic dysregulations most likely to underpin the 'thin-fat' phenotype in LBW infants and its associated pathological consequences. Our analyses reveal hitherto poorly understood maternal nutrition-dependent mechanisms most likely to promote and sustain the self-perpetuating high disease burden, especially in the Indian population. This work suggests that it most probably is the metabolic consequence of 'ill-nutrition' - the recent and rapid dietary shifts to high salt, high saturated fats and high sugar but low micronutrient diets - over an adaptation to 'thrifty metabolism' which must be addressed in interventions aiming to significantly alleviate the leading risk factors for health deterioration in India.

Nutraceuticals: unlocking newer paradigms in the mitigation of inflammatory lung diseases

Persistent respiratory tract inflammation contributes to the pathogenesis of various chronic respiratory diseases, such as asthma, chronic obstructive pulmonary disease, and pulmonary fibrosis. These inflammatory respiratory diseases have been a major public health concern as they are the leading causes of worldwide mortality and morbidity, resulting in heavy burden on socioeconomic growth throughout these years. Although various therapeutic agents are currently available, the clinical applications of these agents are found to be futile due to their adverse effects, and most patients remained poorly controlled with a low quality of life. These drawbacks have necessitated the development of novel, alternative therapeutic agents that can effectively improve therapeutic outcomes. Recently, nutraceuticals such as probiotics, vitamins, and phytochemicals have gained increasing attention due to their nutritional properties and therapeutic potential in modulating the pathological mechanisms underlying inflammatory respiratory diseases, which could ultimately result in improved disease control and overall health outcomes. As such, nutraceuticals have been held in high regard as the possible alternatives to address the limitations of conventional therapeutics, where intensive research are being performed to identify novel nutraceuticals that can positively impact various inflammatory respiratory diseases. This review provides an insight into the utilization of nutraceuticals with respect to their molecular mechanisms targeting multiple signaling pathways involved in the pathogenesis of inflammatory respiratory diseases.

Dose-dependent hepatic toxicity and oxidative stress on exposure to nano and bulk selenium in mice

Selenium is an essential mineral naturally found in soil, water, and some of the food and is required as essential elements in human and animal body. Se supplementation is required especially for those having Se deficiency. Food supplement of selenium has several forms such as selenocysteine, selenite, selenomethionine, and selenate. Recently, Se supplement as selenium nanoparticles (SeNPs) has gained worldwide attention due to its bioactivities and properties. In the present study, we determined the potential hepatotoxicity of nano and bulk selenium using low and high doses in mice. Twenty-five Swiss albino mice (n=5) were randomly divided into 5 groups and treated orally for 28 days: Group 1: sterile saline (0.9%) as a control; Group 2: sodium selenite (1mg/kg); Group 3: sodium selenite (4mg/kg); Group 4: selenium nanoparticles (1mg/kg); and Group 5: selenium nanoparticles (4mg/kg). Administration of nano-selenium (70-90 nm) led to an increase in the activities of serum transaminases (ALT and AST), while no significant effects were noted on biochemical variables indicative of changes in heme synthesis pathway and oxidative stress like blood δ-aminolevulinic acid dehydratase (δ-ALAD), hepatic reactive oxygen species (ROS), catalase activity, superoxide dismutase (SOD), malondialdehyde assay (MDA), reduced glutathione (GSH) and oxidized glutathione (GSSG), glutathione peroxidase (GPx) compared to controls, and a high dose of sodium selenite. Our results suggest that nano-selenium at low dose (1mg/kg) exhibited antioxidant effects in the liver compared to the high dose (4mg/kg) of SeNPs and sodium selenite (1 and 4 mg/kg). The data from the present study might be useful for pharmacologists and toxicologists in providing future directions while designing selenium-based therapeutic strategies.

Association of Urinary and Dietary Selenium and of Serum Selenium Species with Serum Alanine Aminotransferase in a Healthy Italian Population

The trace element selenium is of considerable interest due to its toxic and nutritional properties, which markedly differ according to the dose and the chemical form. It has been shown that excess selenium intake increases the risk of type 2 diabetes and, possibly, other metabolic diseases like hyperlipidemia and non-alcoholic fatty liver disease (NAFLD). For the latter, however, epidemiologic evidence is still limited. We carried out a cross-sectional study recruiting 137 healthy blood donors living in Northern Italy and assessed their exposure to selenium through different methods and measuring serum selenium species. We performed linear and spline regression analyses to assess the relation of selenium and its forms with serum alanine aminotransferase (ALT) levels, a marker of NAFLD. Urinary selenium levels were positively and somewhat linearly correlated with ALT (beta regression coefficient (β) 0.11). Conversely, the association of dietary selenium intake with ALT was positive up to 100 µg/day and null above that amount (β 0.03). Total serum selenium was inversely associated with ALT up to 120 µg/L, and slightly positive above that amount. Concerning the different serum selenium species, ALT positively correlated with two organic forms, selenocysteine (β 0.27) and glutathione peroxidase-bound selenium (β 0.09), showed a U-shaped relation with the inorganic tetravalent form, selenite, and an inverse association with human serum albumin-bound selenium (β -0.56). Our results suggest that overall exposure to selenium, and more specifically to some of its chemical forms, is positively associated with ALT, even at levels so far generally considered to be safe. Our findings add to the evidence suggesting that low-dose selenium overexposure is associated with NAFLD.

Maternal prenatal selenium levels and child risk of neurodevelopmental disorders: A prospective birth cohort study

Selenium (Se) is an essential trace element involved in various biological processes, including neurodevelopment. Available literature indicates that both Se deficiency and excess may be detrimental to health. It is also known that Se can cross the placenta from maternal to fetal circulation. To date, the role of maternal Se status in child long-term neurodevelopment is largely unexplored. This study investigated the temporal and dose-response associations between maternal Se status and child risk of neurodevelopmental disorders including autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD). It consisted of 1550 mother-infant dyads from the Boston Birth Cohort. Maternal red blood cell (RBC) Se levels were measured in samples collected within 72 h of delivery (biomarker of third trimester Se status). Pediatric neurodevelopmental diagnoses were obtained from electronic medical records. Data analyses showed that maternal RBC Se levels were positively associated with child risk of developing ASD, with an adjusted odds ratio of 1.49 for ASD (95% CI: 1.09, 2.02) per IQR increase in Se. There was also a positive association between maternal Se and ADHD (OR: 1.29; 95% CI: 1.04, 1.56, per IQR increase in Se). These associations remained robust even after adjusting for pertinent covariables; and there was no significant interaction between Se and these covariables. Our findings suggest that prenatal exposure to high maternal Se levels may adversely affect child neurodevelopment. Our findings warrant further investigation; if confirmed, optimizing maternal prenatal Se levels may be necessary to maximize its health benefits while preventing undue risk.

Recent advances in technologies for removal and recovery of selenium from (waste)water: A systematic review

Selenium (Se) is distributed into different environmental compartments by natural and anthropogenic activities, and generally discharged in the form of selenate [SeO₄^2-] and selenite [SeO₃^2-], which are both toxic. Physical-chemical and biological treatment processes have been reported to exhibit good treatment efficiencies for Se from aqueous streams, only a few demonstrated to achieve effluent concentrations <5 μg/L. Moreover, there are only a few numbers of studies that describe the progress in technological developments over the last decade. Therefore, to unify the state of knowledge, identify ongoing research trends, and determine the challenges associated with available technologies, this systematic review critically analyses the published research on Se treatment. Specific topics covered in this review include (1) Se chemistry, toxicity, sources and legislation, (2) types of Se treatment technologies, (3) development in Se treatment approaches, (4) Se recovery and circular economy and (5) future prospects. The current research has been found to majorly focused on Se removal via adsorption techniques. However, the key challenges facing Se treatment technologies are related to the presence of competing ions in the solution and the persistence of selenate compared to selenite during their reduction.

Influence of Selenium Biofortification on the Growth and Bioactive Metabolites of Ganoderma lucidum

Selenium biofortification of edible and medicinal mushrooms is an effective way to produce selenium-enriched food supplements. Ganoderma lucidum is the typical one with excellent biological activity. This study investigated G. lucidum growth and bioactive metabolites alterations during liquid culture with different concentrations of selenite. Low selenium levels did not affect growth and mycelia morphology, whereas high selenium levels negatively influenced growth, dramatically decreased biomass, caused nucleic acid and protein leakage, damaged cell walls and membranes, and resulted in indicators such as degraded cells, a red color, and an unpleasant odor. Through headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) analysis, ten volatile Se compounds were identified in G. lucidum with 200 ppm selenite, which led to an odor change, whereas only three with 50 ppm selenite. SeMet was the major selenoamino acid in the 50 ppm selenite group by high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS), but more MeSeCys was produced with 200 ppm selenite. Polysaccharide yields were promoted and inhibited with 50 and 200 ppm selenite, respectively. These results provide comprehensive insights into the effects of selenite on G. lucidum in liquid culture and are beneficial for functional selenium-enriched mushroom production and improving nutritive values.

Biogenic Selenium Nanoparticles: Potential Solution to Oxidative Stress Mediated Inflammation in Rheumatoid Arthritis and Associated Complications

Rheumatoid arthritis (RA) is a common chronic inflammation-mediated disorder having systematic complications. RA triggers a self-directed inflammatory and immunological cascade that culminates in joint destruction. Though a range of treatment options are available, none of them are without adverse effects and this has led researchers to search for alternative solutions. Nanomedicine has emerged as a powerful therapeutic alternative, and selenium (Se) is an essential micronutrient trace element that has a crucial role in human health and disease. Selenium nanoparticles (SeNPs) derived from biological sources, such as plants, bacteria, fungi, and proteins, have exhibited remarkable candidate properties and toxicological profiles, and hence have shown potential to be used as antirheumatic agents. The potential of SeNPs can be attributed to the effect of functional groups bound to them, concentration, and most importantly to their nano range size. The antirheumatic effect of SeNPs is considerable due to its potential in amelioration of oxidative stress-mediated inflammation via downregulation of radical and nonradical species, markers of inflammation, and upregulation of inherent antioxidant defenses. The size and concentration impact of SeNPs has been shown in the subsequent antioxidant and anti-inflammatory properties. Moreover, the article emphasizes the role of these biogenic SeNPs as a notable option in the nanomedicine arena that needs to be further studied as a prospective remedial alternative to cure RA and medication-related adverse events.

Selenium Fortification Alters the Growth, Antioxidant Characteristics and Secondary Metabolite Profiles of Cauliflower (Brassica oleracea var. botrytis) Cultivars in Hydroponic Culture

Nowadays the importance of selenium for human health is widely known, but most of the plants are poor in terms of selenium storage and accumulation because of the low selenium mineralization potential of the soil. For this purpose, foliar application of different sodium selenate concentrations (0, 5, 10, 15, 20 mg/L) was used to treat the cauliflower cultivars "Clapton" and "Graffiti". Higher yields and other related vegetative attributes were improved at 10 and 15 mg/L sodium selenate application. At a concentration of 10 mg/L sodium selenate, photosynthetic pigments, total phenolic compounds and antioxidant capacity were enhanced in both cultivars, but the "Graffiti" cultivar responded stronger than the "Clapton" cultivar. The glucosinolates were accumulated in response to selenium fortification and the highest amounts were found in the "Graffiti" cultivar at 10 mg/L. Selenium accumulated concentration-dependently and rose with higher fertilization levels. In general, foliar application of selenium at 10 mg/L led to an accumulation of secondary metabolites and also positively affected the growth and yield of florets.

Therapeutic potential of thymoquinone in combination therapy against cancer and cancer stem cells

The long-term success of standard anticancer monotherapeutic strategies has been hampered by intolerable side effects, resistance to treatment and cancer relapse. These monotherapeutic strategies shrink the tumor bulk but do not effectively eliminate the population of self-renewing cancer stem cells (CSCs) that are normally present within the tumor. These surviving CSCs develop mechanisms of resistance to treatment and refuel the tumor, thus causing cancer relapse. To ensure durable tumor control, research has moved away from adopting the monotreatment paradigm towards developing and using combination therapy. Combining different therapeutic modalities has demonstrated significant therapeutic outcomes by strengthening the anti-tumor potential of monotreatment against cancer and cancer stem cells, mitigating their toxic adverse effects, and ultimately overcoming resistance. Recently, there has been growing interest in combining natural products from different sources or with clinically used chemotherapeutics to further improve treatment efficacy and tolerability. Thymoquinone (TQ), the main bioactive constituent of Nigella sativa, has gained great attention in combination therapy research after demonstrating its low toxicity to normal cells and remarkable anticancer efficacy in extensive preclinical studies in addition to its ability to target chemoresistant CSCs. Here, we provide an overview of the therapeutic responses resulting from combining TQ with conventional therapeutic agents such as alkylating agents, antimetabolites and antimicrotubules as well as with topoisomerase inhibitors and non-coding RNA. We also review data on anticancer effects of TQ when combined with ionizing radiation and several natural products such as vitamin D3, melatonin and other compounds derived from Chinese medicinal plants. The focus of this review is on two outcomes of TQ combination therapy, namely eradicating CSCs and treating various types of cancers. In conclusion, the ability of TQ to potentiate the anticancer activity of many chemotherapeutic agents and sensitize cancer cells to radiotherapy makes it a promising molecule that could be used in combination therapy to overcome resistance to standard chemotherapeutic agents and reduce their associated toxicities.

The Relevance of Plant-Derived Se Compounds to Human Health in the SARS-CoV-2 (COVID-19) Pandemic Era

Dietary selenium (Se)-compounds accumulated in plants are essential for human metabolism and normal physiological processes. Inorganic and organic Se species can be readily absorbed by the human body, but are metabolized differently and thus exhibit distinct mechanisms of action. They can act as antioxidants or serve as a source of Se for the synthesis of selenoproteins. Selenocysteine, in particular, is incorporated at the catalytic center of these proteins through a specific insertion mechanism and, due to its electronic features, enhances their catalytic activity against biological oxidants. Selenite and other Se-organic compounds may also act as direct antioxidants in cells due to their strong nucleophilic properties. In addition, Se-amino acids are more easily subjected to oxidation than the corresponding thiols/thioethers and can bind redox-active metal ions. Adequate Se intake aids in preventing several metabolic disorders and affords protection against viral infections. At present, an epidemic caused by a novel coronavirus (SARS-CoV-2) threatens human health across several countries and impacts the global economy. Therefore, Se-supplementation could be a complementary treatment to vaccines and pharmacological drugs to reduce the viral load, mutation frequency, and enhance the immune system of populations with low Se intake in the diet.

Comparison of nanoparticle-selenium, selenium-enriched yeast and sodium selenite on the alleviation of cadmium-induced inflammation via NF-kB/IκB pathway in heart

Cadmium (Cd) has been confirmed as an environmental contaminant, which potential threats health impacts to humans and animals. Selenium (Se) as a beneficial element that alleviates the negative effects of Cd toxicity. Se mainly exists in two forms in food nutrients including organic Se usually as (Se-enriched yeast (SeY)) and inorganic Se (sodium selenite (SSe)). Nanoparticle of Se (Nano-Se), a new form Se, which is synthesized by the bioreduction of Se species, which attracted significant attention recently. However, compared the superiority alleviation effects of Nano-Se, SeY or SSe on Cd-induced toxicity and related mechanisms are still poorly understood. The purpose of this study was to compare the superiority antagonism effects of Nano-Se, SeY and SSe on Cd-induced inflammation response via NF-kB/IκB pathway in the heart. The present study demonstrated that exposed to Cd obviously increased the accumulation of Cd, disruption of ion homeostasis and depressed the ratios of K⁺/Na⁺ and Mg²⁺/Ca²⁺ via ion chromatography mass spectrometry (ICP-MS) detecting the heart specimens. In the results of histological and ultrastructure observation, typical inflammatory infiltrate characteristics and mitochondria and nuclear structure alterations in the hearts of Cd group were confirmed. Cd treatment enhanced the inducible nitric oxide synthase (iNOS) activities and NOS isoforms expression via NF-kB/IκB pathway to promote inflammation response. However, the combined treatment of Cd-exposed animals with Nano-Se was more effective than SeY and SSe in reversing Cd-induced histopathological changes and iNOS activities increased, reducing Cd accumulation and antagonizing Cd-triggered inflammation response via NF-kB/IκB pathway in chicken hearts. Overall, Se applications, especially Nano-Se, can be most efficiently used for relieving cardiotoxicity by exposed to Cd compared to other Se compound.

Intersection between Obesity, Dietary Selenium, and Statin Therapy in Brazil

Obesity is among the most alarming health concerns, impacting public health and causing a socioeconomic challenge, especially in developing countries like Brazil, where approximately one quart of the population presents obesity. As an established risk factor for numerous comorbidities with a multifactorial etiology, obesity is a consequence of energy-dense overfeeding, however with significant undernourishment, leading to excessive adipose tissue accumulation and dysfunction, dyslipidemia, and micronutrient deficiencies. About 60% of patients with obesity take statins, a cholesterol-lowering medication, to curb dyslipidemia, with ~10% of these patients presenting various myopathies as side effects. Statins act upon the rate-limiting enzyme of cholesterol biosynthesis in the liver, which is a pathway providing intermediates to the synthesis of selenoproteins, i.e., enzymes containing the micronutrient selenium. Statins have been postulated to negatively impact selenoprotein synthesis, particularly in conditions of selenium deficiency, and potentially implicated in the myopathies occurring as side effects of statins. The Brazilian population is prone to selenium deficiency, hence could be considered more susceptible to statin side effects. This review examines the specific consequences to the Brazilian population of the harmful intersection between obesity development and concomitant micronutrient deficiencies, particularly selenium, combined with statin treatment in the context of nutrition in Brazil.

Selenium

Selenium (Se) is an element commonly found in the environment at different levels. Its compounds are found in soil, water, and air. This element is also present in raw materials of plant and animal origin, so it can be introduced into human organisms through food. Selenium is a cofactor of enzymes responsible for the antioxidant protection of the body and plays an important role in regulating inflammatory processes in the body. A deficiency in selenium is associated with a number of viral diseases, including COVID-19. This element, taken in excess, may have a toxic effect in the form of joint diseases and diseases of the blood system. Persistent selenium deficiency in the body may also impact infertility, and in such cases supplementation is needed.

Selenium in Human Health and Gut Microflora: Bioavailability of Selenocompounds and Relationship With Diseases

This review covers current knowledge of selenium in the dietary intake, its bioavailability, metabolism, functions, biomarkers, supplementation and toxicity, as well as its relationship with diseases and gut microbiota specifically on the symbiotic relationship between gut microflora and selenium status. Selenium is essential for the maintenance of the immune system, conversion of thyroid hormones, protection against the harmful action of heavy metals and xenobiotics as well as for the reduction of the risk of chronic diseases. Selenium is able to balance the microbial flora avoiding health damage associated with dysbiosis. Experimental studies have shown that inorganic and organic selenocompounds are metabolized to selenomethionine and incorporated by bacteria from the gut microflora, therefore highlighting their role in improving the bioavailability of selenocompounds. Dietary selenium can affect the gut microbial colonization, which in turn influences the host's selenium status and expression of selenoproteoma. Selenium deficiency may result in a phenotype of gut microbiota that is more susceptible to cancer, thyroid dysfunctions, inflammatory bowel disease, and cardiovascular disorders. Although the host and gut microbiota benefit each other from their symbiotic relationship, they may become competitors if the supply of micronutrients is limited. Intestinal bacteria can remove selenium from the host resulting in two to three times lower levels of host's selenoproteins under selenium-limiting conditions. There are still gaps in whether these consequences are unfavorable to humans and animals or whether the daily intake of selenium is also adapted to meet the needs of the bacteria.

A Mechanistic Link Between Selenium and Coronavirus Disease 2019 (COVID-19)

PURPOSE OF REVIEW

Coronavirus disease 2019 (COVID-19) is a rapidly emerging disease caused by a highly contagious virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and this disease has affected millions of people across the world and led to hundreds of thousands of deaths worldwide. Nutrition is a key factor related to this disease, and nutritional status may determine the risk and outcomes of SARS-CoV-2 infection. Selenium is one of the major trace elements required for redox functions and has significant roles in viral infections. The purpose of this review was to examine the current evidence on the role of selenium in COVID-19. We reviewed studies on selenium and COVID-19, and other relevant studies to understand how selenium status can modify the risk of SARS-CoV-2 infection, and how selenium status might affect a person post-infection.

RECENT FINDINGS

We found that oxidative stress is a characteristic feature of COVID-19 disease, which is linked with the immunopathological disorder observed in individuals with severe COVID-19. Selenium plays a key role in strengthening immunity, reducing oxidative stress, preventing viral infections and supporting critical illness. Moreover, selenium deficiency is related to oxidative stress and hyperinflammation seen in critical illness, and selenium deficiency is found to be associated with the severity of COVID-19 disease. Selenium supplementation at an appropriate dose may act as supportive therapy in COVID-19. Future studies in large cohorts of COVID-19 are warranted to verify the benefits of selenium supplementation for reducing risk and severity of COVID-19.