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This document is a comment on a review paper titled "Could Selenium Supplementation Prevent COVID-19? A Comprehensive Review of Available Studies." The authors of the comment are experienced selenium researchers who take issue with the assessments made in the review. They argue that the review is not comprehensive and fails to include important studies that support the association between selenium and COVID-19 outcomes. The authors also address specific criticisms made by the reviewers regarding their own work and highlight the importance of further research into the role of selenium in COVID-19. [Extracted from the article]

Iodine supply is crucial during pregnancy to ensure that the proper thyroid function of mother and baby support fetal brain development. Little is known about iodine status or its dietary determinants in pregnant women in the Republic of Cyprus. We therefore recruited 128 pregnant women at their first-trimester ultrasound scan to a cross-sectional study. We collected spot-urine samples for the measurement of urinary iodine concentration (UIC, µg/l) and creatinine concentration (Creat, g/l), the latter of which allows us to correct for urine dilution and to compute the iodine-to-creatinine ratio (UI/Creat). Women completed a FFQ and a general questionnaire. We used a General Linear model to explore associations between maternal and dietary characteristics with UI/Creat. The median UIC (105 µg/l) indicated iodine deficiency according to the WHO criterion (threshold for adequacy = 150 µg/l), and the UI/Creat was also low at 107 µg/g. Only 32 % (n 45) of women reported the use of iodine-containing supplements; users had a higher UI/Creat than non-users (131 µg/g v. 118 µg/g), though this difference was NS in the adjusted analysis (P = 0·37). Of the dietary components, only egg intake was significantly associated with a higher UI/Creat in adjusted analyses (P = 0·018); there was no significant association with milk, dairy products or fish intake. Our results suggest that pregnant women in Cyprus have inadequate iodine status and are at risk of mild-to-moderate iodine deficiency. Further research on dietary sources in this population is required. [ABSTRACT FROM AUTHOR]

We begin by arguing that the often used algorithm for the discovery and use of disease risk factors, stepwise logistic regression, is unstable. We then argue that there are other algorithms available that are much more stable and reliable (e.g. the lasso and gradient boosting). We then propose a protocol for the discovery and use of risk factors using lasso or boosting variable selection. We then illustrate the use of the protocol with a set of prostate cancer data and show that it recovers known risk factors. Finally, we use the protocol to identify new and important SNP based risk factors for prostate cancer and further seek evidence for or against the hypothesis of an anticancer function for Selenium in prostate cancer. We find that the anticancer effect may depend on the SNP-SNP interaction and, in particular, which alleles are present. [ABSTRACT FROM AUTHOR]

Breastfeeding mothers often report perceived insufficient milk (PIM) believing their infant is crying too much, which leads to introducing formula and the early abandonment of breastfeeding. We sought to determine if infant crying was associated with reported PIM (yes/no) and number of problems associated with lactation (lactation problem score [LPS] 6‐point Likert scale) before formula introduction. Primiparous breastfeeding mothers were recruited at birth and visited at 1, 2 and 4 weeks. Among those fully breastfeeding at 1 week (N = 230), infant crying variables based on maternal reports were not associated with PIM at 1 week, but LPS was. However, a mother's expectation that her infant would cry more than other infants was associated with increased odds of reporting PIM at 2 and 4 weeks, as were delayed onset of lactation and previous LPS. At 1 week, crying variables (frequency, difficulty in soothing) were associated with LPS along with percent weight change. Delayed onset of lactation, infant care style, number of breastfeeds and previous LPS were longitudinally associated with change in LPS from 1 to 2 weeks and 2 to 4 weeks. Our data suggest that reported infant crying is associated with PIM and LPS in the first 4 weeks of life. Guidance on what to expect in crying behaviour and the impact of infant care style may be beneficial in reducing PIM and LPS in the first month. [ABSTRACT FROM AUTHOR]

Background Mild-to-moderate iodine deficiency, particularly in pregnancy, is prevalent; this is of concern because observational studies have shown negative associations with child neurodevelopment. Although neither the benefits nor the safety of iodine supplementation in pregnancy in areas of mild-to-moderate deficiency are well researched, such supplementation is increasingly being recommended by health authorities in a number of countries. Objectives By reviewing the most recent published data on the effects of iodine supplementation in mildly-to-moderately deficient pregnant women on maternal and infant thyroid function and child cognition, we aimed to determine whether the evidence was sufficient to support recommendations in these areas. Methods A systematic review of randomized controlled trials (RCTs), non-RCT interventions, and observational studies was conducted. To identify relevant articles, we searched the PubMed and Embase databases. We defined mild-to-moderate iodine deficiency as a baseline median urinary iodine concentration (UIC) of 50–149 µg/L. Eligible studies were included in meta-analyses. Results In total, 37 publications were included—10 RCTs, 4 non-RCT interventions, and 23 observational studies. Most studies showed no effect of iodine supplementation on maternal or infant thyroid-stimulating hormone and free thyroxine. Most RCTs found that supplementation reduced maternal thyroglobulin and in 3 RCTs, it prevented or diminished the increase in maternal thyroid volume during pregnancy. Three RCTs addressed child neurodevelopment; only 1 was adequately powered. Meta-analyses of 2 RCTs showed no effect on child cognitive [mean difference (MD): −0.18; 95% CI: −1.22, 0.87], language (MD: 1.28; 95% CI: −0.28, 2.83), or motor scores (MD: 0.28; 95% CI: −1.10, 1.66). Conclusions There is insufficient good-quality evidence to support current recommendations for iodine supplementation in pregnancy in areas of mild-to-moderate deficiency. Well-designed RCTs, with child cognitive outcomes, are needed in pregnant women who are moderately deficient (median UIC < 100 µg/L). Maternal intrathyroidal iodine stores should be considered in future trials by including appropriate measures of preconceptional iodine intake. This review was registered at www.crd.york.ac.uk/prospero as CRD42018100277. [ABSTRACT FROM AUTHOR]

Background: Severe iodine deficiency during pregnancy can cause intellectual disability, presumably through inadequate placental transfer of maternal thyroid hormone to the fetus. The association between mild-to-moderate iodine deficiency and child neurodevelopmental problems is not well understood.Objectives: We investigated the association of maternal iodine status during pregnancy with child attention-deficit hyperactivity disorder (ADHD) and autistic traits.Methods: This was a collaborative study of 3 population-based birth cohorts: Generation R (n = 1634), INfancia y Medio Ambiente (n = 1293), and the Avon Longitudinal Study of Parents and Children (n = 2619). Exclusion criteria were multiple fetuses, fertility treatment, thyroid-interfering medication use, and pre-existing thyroid disease. The mean age of assessment in the cohorts was between 4.4 and 7.7 y for ADHD symptoms and 4.5 and 7.6 y for autistic traits. We studied the association of the urinary iodine-to-creatinine ratio (UI/Creat) <150 μg/g-in all mother-child pairs, and in those with a urinary-iodine measurement at ≤18 weeks and ≤14 weeks of gestation-with the risk of ADHD or a high autistic-trait score (≥93rd percentile cutoff), using logistic regression. The cohort-specific effect estimates were combined by random-effects meta-analyses. We also investigated whether UI/Creat modified the associations of maternal free thyroxine (FT4) or thyroid-stimulating hormone concentrations with ADHD or autistic traits.Results: UI/Creat <150 μg/g was not associated with ADHD (OR: 1.2; 95% CI: 0.7, 2.2; P = 0.56) or with a high autistic-trait score (OR: 0.8; 95% CI: 0.6, 1.1; P = 0.22). UI/Creat <150 μg/g in early pregnancy (i.e., ≤18 weeks or ≤14 weeks of gestation) was not associated with a higher risk of behavioral problems. The association between a higher FT4 and a greater risk of ADHD (OR: 1.3; 95% CI: 1.0, 1.6; P = 0.017) was not modified by iodine status.Conclusions: There is no consistent evidence to support an association of mild-to-moderate iodine deficiency during pregnancy with child ADHD or autistic traits. [ABSTRACT FROM AUTHOR]

Hashimoto's thyroiditis (HT) and Graves' disease (GD) are examples of autoimmune thyroid disease (AITD), the commonest autoimmune condition. Antibodies to thyroid peroxidase (TPO), the enzyme that catalyses thyroid-hormone production and antibodies to the receptor for the thyroid-stimulating hormone, are characteristic of HT and GD, respectively. It is presently accepted that genetic susceptibility, environmental factors, including nutritional factors and immune disorders contribute to the development of AITD. Aiming to investigate the effect of iodine, iron and selenium in the risk, pathogenesis and treatment of thyroid disease, PubMed and the Cochrane Library were searched for relevant publications to provide a narrative review. Iodine: chronic exposure to excess iodine intake induces autoimmune thyroiditis, partly because highly-iodinated thyroglobulin (Tg) is more immunogenic. The recent introduction of universal salt iodisation can have a similar, although transient, effect. Iron: iron deficiency impairs thyroid metabolism. TPO is a haem enzyme that becomes active only after binding haem. AITD patients are frequently iron-deficient since autoimmune gastritis, which reduces iron absorption and coeliac disease which causes iron loss, are frequent co-morbidities. In two-thirds of women with persistent symptoms of hypothyroidism despite appropriate levothyroxine therapy, restoration of serum ferritin above 100 µg/l ameliorated symptoms. Selenium: selenoproteins are essential to thyroid action. In particular, the glutathione peroxidases remove excessive hydrogen peroxide produced there for the iodination of Tg to form thyroid hormones. There is evidence from observational studies and randomised controlled trials that selenium, probably as selenoproteins, can reduce TPO-antibody concentration, hypothyroidism and postpartum thyroiditis. Appropriate status of iodine, iron and selenium is crucial to thyroid health. [ABSTRACT FROM AUTHOR]

The article discusses research which hypothesized that selenium status was associated with coronavirus disease-2019 (COVID-19) disease outcome in China. Topics covered include the results of comparing cure rate and death rate using the Stata prtest, the association found between the reported cure rates for COVID-19 and selenium status, and the limitations of the study.

As current treatment options in OA are very limited, OA patients would benefit greatly from some ability to self-manage their condition. Since diet may potentially affect OA, we reviewed the literature on the relationship between nutrition and OA risk or progression, aiming to provide guidance for clinicians. For overweight/obese patients, weight reduction, ideally incorporating exercise, is paramount. The association between metabolic syndrome, type-2 diabetes and OA risk or progression may partly explain the apparent benefit of dietary-lipid modification resulting from increased consumption of long-chain omega-3 fatty-acids from oily fish/fish oil supplements. A strong association between OA and raised serum cholesterol together with clinical effects in statin users suggests a potential benefit of reduction of cholesterol by dietary means. Patients should ensure that they meet the recommended intakes for micronutrients such as vitamin K, which has a role in bone/cartilage mineralization. Evidence for a role of vitamin D supplementation in OA is unconvincing. [ABSTRACT FROM AUTHOR]

Iodine is an essential micronutrient incorporated into thyroid hormones. Although iodine deficiency can lead to a broad spectrum of disorders throughout life, it is most critical in the early stages of development, as the foetal brain is extremely dependent on iodine supply. During the last two decades, our understanding of thyroid physiology during gestation has substantially improved. Furthermore, thyroid hormone receptors have been identified and characterised in placental and embryonic tissues, allowing us to elucidate the maternal-foetal transfer of thyroid hormones. Experimental studies have demonstrated that the cyto-architecture of the cerebral cortex can be irreversibly disturbed in iodine deficiency causing abnormal neuron migratory patterns which are associated with cognitive impairment in children. In this context, the role of iodine as key factor in the programming of foetal and infant neurodevelopment, needs to be revisited with a special focus on areas of mild to moderate iodine deficiency. The objective of this review is to summarize the available evidence from both animals and human studies, for the effect of iodine deficiency (particularly, of maternal hypothyroxinemia) on brain development and neurological or behavioural disorders, such as lower intelligence quotient (IQ) or attention deficit hyperactivity disorder (ADHD). [ABSTRACT FROM AUTHOR]

Iodine deficiency is present in certain groups of the UK population, notably in pregnant women; this is of concern as iodine is required for fetal brain development. UK milk is rich in iodine and is the principal dietary iodine source. UK sales of milk-alternative drinks are increasing but data are lacking on their iodine content. As consumers may replace iodine-rich milk with milk-alternative drinks, we aimed to measure the iodine concentration of those available in the UK. Using inductively coupled plasma-MS, we determined the iodine concentration of seven types of milk-alternative drink (soya, almond, coconut, oat, rice, hazelnut and hemp) by analysing forty-seven products purchased in November/December 2015. For comparison, winter samples of conventional (n 5) and organic (n 5) cows' milk were included. The median iodine concentration of all of the unfortified milk-alternative drinks (n 44) was low, at 7-3 µg/kg, just 1-7% of our value for winter conventional cows' milk (median 438 µg/kg). One brand (not the market leader), fortified its soya, oat and rice drinks with iodine and those drinks had a higher iodine concentration than unfortified drinks, at 280, 287 and 266 µg/kg, respectively. The iodine concentration of organic milk (median 324 µg/kg) was lower than that of conventional milk. Although many milk-alternative drinks are fortified with Ca, at the time of this study, just three of forty-seven drinks were fortified with iodine. Individuals who consume milk-alternative drinks that are not fortified with iodine in place of cows' milk may be at risk of iodine deficiency unless they consume alternative dietary iodine sources. [ABSTRACT FROM AUTHOR]

Seafood intake in pregnancy has been positively associated with childhood cognitive outcomes which could potentially relate to the high vitamin D content of oily fish. However, whether higher maternal vitamin D status (serum 25-hydroxyvitamin D (25(OH)D)) in pregnancy is associated with a reduced risk of offspring suboptimal neurodevelopmental outcomes is unclear. A total of 7065 mother–child pairs were studied from the Avon Longitudinal Study of Parents and Children cohort who had data for both serum total 25(OH)D concentration in pregnancy and at least one measure of offspring neurodevelopment (pre-school development at 6–42 months; ‘Strengths and Difficulties Questionnaire’ scores at 7 years; intelligence quotient (IQ) at 8 years; reading ability at 9 years). After adjustment for confounders, children of vitamin D-deficient mothers (<50·0 nmol/l) were more likely to have scores in the lowest quartile for gross-motor development at 30 months (OR 1·20; 95 % CI 1·03, 1·40), fine-motor development at 30 months (OR 1·23; 95 % CI 1·05, 1·44) and social development at 42 months (OR 1·20; 95 % CI 1·01, 1·41) than vitamin D-sufficient mothers (≥50·0 nmol/l). No associations were found with neurodevelopmental outcomes, including IQ, measured at older ages. However, our results suggest that deficient maternal vitamin D status in pregnancy may have adverse effects on some measures of motor and social development in children under 4 years. Prevention of vitamin D deficiency may be important for preventing suboptimal development in the first 4 years of life. [ABSTRACT FROM AUTHOR]

The deficiency of Se, an essential micronutrient, has been implicated in adverse pregnancy outcomes. Our study was designed to determine total serum Se, selenoproteins (extracellular glutathione peroxidase (GPx-3), selenoprotein P (SeP)), selenoalbumin (SeAlb) and selenometabolites in healthy women and their newborns at delivery. This cross-sectional study included eighty-three healthy mother–baby couples. Total Se and Se species concentrations were measured in maternal and umbilical cord sera by an in-series coupling of two-dimensional size-exclusion and affinity HPLC. Additional measurements of serum SeP concentration and of serum GPx-3 enzyme activity were carried out using ELISA. Total Se concentration was significantly higher in maternal serum than in cord serum (68·9 (sd 15·2) and 56·1 (sd 14·6) µg/l, respectively; P<0·01). There were significant correlations between selenoprotein and SeAlb concentrations in mothers and newborns, although they also showed significant differences in GPx-3 (11·2 (sd 3·7) v. 10·5 (sd 3·5) µg/l; P<0·01), SeP (42·5 (sd 9·5) v. 28·1 (sd 7·7) µg/l; P<0·01) and SeAlb (11·6 (sd 3·6) v. 14·1 (sd 4·3) µg/l; P<0·01) concentrations in maternal and cord sera, respectively. Serum GPx-3 activity and concentration were positively correlated in mothers (r 0·33; P=0·038) but not in newborns. GPx-3 activity in cord serum was significantly correlated with gestational age (r 0·44; P=0·009). SeAlb concentration was significantly higher in babies, whereas SeP and GPx-3 concentrations were significantly higher in mothers. The differences cannot be explained by simple diffusion; specific transfer mechanisms are probably involved. GPx-3 concentrations in mothers, at delivery, are related to maternal Se status, whereas the GPx-3 activity in cord serum depends on gestational age. [ABSTRACT FROM AUTHOR]

A review of the article on the trace-element concentrations between organic and conventional milk that was previously published in the journal is presented.

Concern has been expressed recently that Se may increase the risk of type 2 diabetes, but this has not been tested in a randomised-controlled trial (RCT) in pregnant women. We took advantage of having stored plasma samples from the Se in Pregnancy Intervention (SPRINT) RCT of Se supplementation in pregnancy to test the effect of Se supplementation on a marker of insulin resistance in UK pregnant women. Because our blood samples were not fasted, we measured plasma adiponectin concentration, a recognised marker of insulin resistance that gives valid measurements in non-fasted samples, as diurnal variability is minor and there is no noticeable effect of food intake. In SPRINT, 230 primiparous UK women were randomised to treatment with Se (60 μg/d) or placebo from 12 weeks of gestation until delivery. We hypothesised that supplementation with Se at a nutritional level would not exacerbate the fall in adiponectin concentration that occurs in normal pregnancy, indicating the lack of an adverse effect on insulin resistance. Indeed, there was no significant difference between the two groups in the change in adiponectin from 12 to 35 weeks (P=0·938), nor when the analysis was restricted to the bottom or top quartiles of baseline whole-blood Se (P=0·515 and 0·858, respectively). Cross-sectionally, adiponectin concentration was not associated with any parameter of Se status, either at 12 or 35 weeks. It is reassuring that a nutritional dose of Se had no adverse effect on the concentration of adiponectin, a biomarker of insulin resistance, in pregnant women of modest Se status. [ABSTRACT FROM AUTHOR]

Background: Low selenium status in pregnancy has been associated with a number of adverse conditions. In nonpregnant populations, the selenium status or response to supplementation has been associated with polymorphisms in dimethylglycine dehydrogenase (DMGDH), selenoprotein P (SEPP1) and the glutathione peroxidases [cytosolic glutathione peroxidase (GPx1) and phospholipid glutathione peroxidase (GPx4)]. Objective: We hypothesized that, in pregnant women, these candidate polymorphisms would be associated with selenium status in early pregnancy, its longitudinal change, and the interindividual response to selenium supplementation at 60 μg/d. Design: With the use of stored samples and data from the United Kingdom Selenium in Pregnancy Intervention (SPRINT) study in 227 pregnant women, we carried out genetic-association studies, testing for associations between selenium status, its longitudinal change, and response to supplementation and common genetic variation in DMGDH (rs921943), SEPP1 (rs3877899 and rs7579), GPx1 (rs1050450) and GPx4 (rs713041). Selenium status was represented by the concentration of whole-blood selenium at 12 and 35 wk of gestation, the concentration of toenail selenium at 16 wk of gestation, and plasma glutathione peroxidase (GPx3) activity at 12 and 35 wk of gestation. Results: Our results showed that DMGDH rs921943 was significantly associated with the whole-blood selenium concentration at 12 wk of gestation (P = 0.032), which explained ≤2.0% of the variance. This association was replicated with the use of toenail selenium (P = 0.043). In unsupplemented women, SEPP1 rs3877899 was significantly associated with the percentage change in whole-blood selenium from 12 to 35 wk of gestation (P = 0.005), which explained 8% of the variance. In supplemented women, SEPP1 rs3877899 was significantly associated with the percentage change in GPx3 activity from 12 to 35 wk of gestation (P = 0.01), which explained 5.3% of the variance. Selenium status was not associated with GPx1, GPx4, or SEPP1 rs7579. Conclusions: In agreement with previous studies, we show that the genetic variant rs921943 in DMGDH is significantly associated with selenium status in United Kingdom pregnant women. Notably, our study shows that women who carry the SEPP1 rs3877899 A allele are better able to maintain selenium status during pregnancy, and their GPx3 activity increases more with supplementation, which suggests better protection from low selenium status. The SPRINT study was registered at www.isrctn.com as ISRCTN37927591. [ABSTRACT FROM AUTHOR]

Although cross-sectional studies have shown a positive association between Se and cholesterol concentrations, a recent randomised controlled trial in 501 elderly UK individuals of relatively low-Se status found that Se supplementation for 6 months lowered total plasma cholesterol. The Danish PRECISE (PREvention of Cancer by Intervention with Selenium) pilot study (ClinicalTrials.gov ID: NCT01819649) was a 5-year randomised, double-blinded, placebo-controlled trial with four groups (allocation ratio 1:1:1:1). Men and women aged 60–74 years (n 491) were randomised to 100 (n 124), 200 (n 122) or 300 (n 119) μg Se-enriched yeast or matching placebo-yeast tablets (n 126) daily for 5 years. A total of 468 participants continued the study for 6 months and 361 participants, equally distributed across treatment groups, continued for 5 years. Plasma samples were analysed for total and HDL-cholesterol and for total Se concentrations at baseline, 6 months and 5 years. The effect of different doses of Se supplementation on plasma lipid and Se concentrations was estimated by using linear mixed models. Plasma Se concentration increased significantly and dose-dependently in the intervention groups after 6 months and 5 years. Total cholesterol decreased significantly both in the intervention groups and in the placebo group after 6 months and 5 years, with small and nonsignificant differences in changes in plasma concentration of total cholesterol, HDL-cholesterol, non-HDL-cholesterol and total:HDL-cholesterol ratio between intervention and placebo groups. The effect of long-term supplementation with Se on plasma cholesterol concentrations or its sub-fractions did not differ significantly from placebo in this elderly population. [ABSTRACT FROM PUBLISHER]

Dietary intake/status of the trace mineral Se may affect the risk of developing hypertensive conditions of pregnancy, i.e. pre-eclampsia and pregnancy-induced hypertension (PE/PIH). In the present study, we evaluated Se status in UK pregnant women to establish whether pre-pregnant Se status or Se supplementation affected the risk of developing PE/PIH. The samples originated from the SPRINT (Selenium in PRegnancy INTervention) study that randomised 230 UK primiparous women to treatment with Se (60 μg/d) or placebo from 12 weeks of gestation. Whole-blood Se concentration was measured at 12 and 35 weeks, toenail Se concentration at 16 weeks, plasma selenoprotein P (SEPP1) concentration at 35 weeks and plasma glutathione peroxidase (GPx3) activity at 12, 20 and 35 weeks. Demographic data were collected at baseline. Participants completed a FFQ. UK pregnant women had whole-blood Se concentration lower than the mid-range of other populations, toenail Se concentration considerably lower than US women, GPx3 activity considerably lower than US and Australian pregnant women, and low baseline SEPP1 concentration (median 3·00, range 0·90–5·80 mg/l). Maternal age, education and social class were positively associated with Se status. After adjustment, whole-blood Se concentration was higher in women consuming Brazil nuts (P= 0·040) and in those consuming more than two seafood portions per week (P= 0·054). A stepwise logistic regression model revealed that among the Se-related risk factors, only toenail Se (OR 0·38, 95 % CI 0·17, 0·87, P= 0·021) significantly affected the OR for PE/PIH. On excluding non-compliers with Se treatment, Se supplementation also significantly reduced the OR for PE/PIH (OR 0·30, 95 % CI 0·09, 1·00, P= 0·049). In conclusion, UK women have low Se status that increases their risk of developing PE/PIH. Therefore, UK women of childbearing age need to improve their Se status. [ABSTRACT FROM PUBLISHER]

As intra-thyroidal iodine stores should be maximised before conception to facilitate the increased thyroid hormone production during pregnancy, women who are planning to become pregnant should ideally consume 150 μg iodine/d (US RDA). As few UK data exist for this population group, a cross-sectional study was carried out at the University of Surrey to assess the iodine intake and status of women of childbearing age. Total iodine excretion was measured from 24 h urine samples in fifty-seven women; iodine intake was estimated by assuming that 90 % of ingested iodine was excreted. The average iodine intake was also estimated from 48 h food diaries that the participants completed. The median urinary iodine concentration value (63·1 μg/l) indicated the group to be mildly iodine deficient by WHO criteria. By contrast, the median 24 h urinary iodine excretion value (149·8 μg/24 h) indicated a relatively low risk of iodine deficiency. The median estimated iodine intake, extrapolated from urinary excretion, was 167 μg/d, whereas it was lower, at 123 μg/d, when estimated from the 48 h food diaries. Iodine intake estimated from the food diaries and 24 h urinary iodine excretion were strongly correlated (r 0·75, P< 0·001). The intake of milk, eggs and dairy products was positively associated with iodine status. The iodine status of this UK cohort is probably a best-case scenario as the women were mostly nutrition students and were recruited in the winter when milk-iodine content is at its highest; further study in more representative cohorts of UK women is required. The present study highlights the need for revised cut-off values for iodine deficiency that are method- and age group-specific. [ABSTRACT FROM PUBLISHER]

Higher selenium status has been shown to improve the clinical outcome of infections caused by a range of evolutionally diverse viruses, including SARS-CoV-2. However, the impact of SARS-CoV-2 on host-cell selenoproteins remains elusive. The present study investigated the influence of SARS-CoV-2 on expression of selenoprotein mRNAs in Vero cells. SARS-CoV-2 triggered an inflammatory response as evidenced by increased IL-6 expression. Of the 25 selenoproteins, SARS-CoV-2 significantly suppressed mRNA expression of ferroptosis-associated GPX4, DNA synthesis-related TXNRD3 and endoplasmic reticulum-resident SELENOF, SELENOK, SELENOM and SELENOS. Computational analysis has predicted an antisense interaction between SARS-CoV-2 and TXNRD3 mRNA, which is translated with high efficiency in the lung. Here, we confirmed the predicted SARS-CoV-2/ TXNRD3 antisense interaction in vitro using DNA oligonucleotides, providing a plausible mechanism for the observed mRNA knockdown. Inhibition of TXNRD decreases DNA synthesis which is thereby likely to increase the ribonucleotide pool for RNA synthesis and, accordingly, RNA virus production. The present findings provide evidence for a direct inhibitory effect of SARS-CoV-2 replication on the expression of a specific set of selenoprotein mRNAs, which merits further investigation in the light of established evidence for correlations between dietary selenium status and the outcome of SARS-CoV-2 infection. • Effect of SARS-CoV-2 on selenoprotein mRNA was investigated in Vero cells. • SARS-CoV-2 reduces mRNA concentration of GPX4 hence increases risk of ferroptosis. • SARS-CoV-2 lowers mRNA concentrations of four ER-resident selenoproteins (F/K/M/S). • SARS-CoV-2/ TXNRD3 antisense interaction causes knockdown of TXNRD3 mRNA. [ABSTRACT FROM AUTHOR]