Does dietary intake of selenium protect against cancer? A systematic review and meta-analysis of population-based prospective studies

Zinc, copper, copper-to-zinc ratio, and other biometals in blood serum and tumor tissue of patients with colorectal cancer

The objective of the present study was to assess serum and cancerous tissue biometal levels in colorectal cancer (CRC) patients, and its relation to disease severity. A total of 90 CRC patients and 97 controls were involved in the present study. The level of biometals in blood serum and colon tissues (only in CRC cases) was evaluated by inductively-coupled plasma mass-spectrometry. CRC patients are characterized by lower serum Ca, Fe, Se, and Zn, as well as higher serum Co, Cu, Mg, V, and Cu/Zn ratio compared to healthy controls. The lowest serum Zn levels and the highest Cu concentration and Cu/Zn ratio were observed in patients with the largest tumor size. Regression analysis demonstrated that tumor size is a significant negative predictor of serum Se levels, being positively associated with serum Cu/Zn values. The degree of metastasis to regional lymph nodes was inversely associated with circulating Ca, Co, Mg, Zn, and Mn levels. Serum Mg and Mn levels were positively associated with the stage of the disease and tumor location, respectively. Cancerous tissue Ca and Mo levels were lower, while Mg content was higher compared to healthy adjacent tissues. In cancerous tissues a constant but non-significant trend to elevation of tissue Zn content with increasing tumor size was observed. In addition, serum Cu, Zn, and Cu/Zn values positively correlated with the respective tumor values. These findings demonstrate that altered biometal metabolism is associated with CRC, while systemic Cu/Zn ratio may be indicative of Cu and Zn imbalance in cancerous tissue.

Cancer prevention at the microscopic level with the potent power of micronutrients

Cancer remains a leading cause of morbidity and mortality worldwide, necessitating ongoing exploration of effective prevention strategies. Micronutrients, vital for maintaining cellular health, offer promising avenues for cancer prevention. This review delineates the critical roles of micronutrients in cancer prevention, elucidating their mechanisms at the cellular level. Focusing on essential vitamins and minerals like Vitamins A, C, D, E, selenium, and zinc, we explore their profound effects on fundamental cellular processes such as DNA repair, oxidative stress regulation, cellular proliferation, and immune surveillance. These nutrients, characterized by their antioxidative, anti-inflammatory, and immune-enhancing properties, have shown potential in reducing the risk of cancer. The article synthesizes outcomes from a broad spectrum of clinical trials, epidemiological studies, and systematic reviews to evaluate the efficacy of micronutrients in thwarting cancer development. This critical analysis explores significant trials, addresses controversies in nutrient efficacy, and highlights the implications for clinical practice and public health policy. The review underscores the importance of integrating nutritional strategies into comprehensive cancer prevention frameworks and suggests directions for future research to optimize the preventive potentials of micronutrients.

The toxicological analysis of problematic and sophisticated elements (Ni, Cr, and Se) in Food for Special Medical Purposes (FSMP) using in pharmacotherapy and clinical nutrition for oncological patients available in Polish pharmacies

This study focuses on FSMPs for oncologic patients, specifically analyzing the toxicological profiles of nickel (Ni), chromium (Cr), and selenium (Se) within these products available in Polish pharmacies. The presence of these elements was quantified using inductively coupled plasma mass spectrometry (ICP-MS). Results indicated variations in the concentrations of Ni, Cr, and Se across different FSMP samples, with some products exceeding the acceptable limits set by regulatory guidelines. The study highlights the potential health risks associated with nickel exposure, including dermatitis and carcinogenesis, and the complex roles of chromium and selenium, which can be both beneficial and harmful depending on their levels. Our findings reveal significant variability in the elemental content across different FSMP products, i.e.: Ni: 0.155-25.488 μg/portion, Cr: 0.076-28.726 μg/portion and Se: 0.083-20.304 μg/portion). Notably, selenium levels in FSMPs showed considerable discrepancies compared to manufacturers' declarations, averaging only about 20% of the stated values. Regulatory assessments based on the Acceptable Daily Intake (ADI) and Permitted Daily Exposure (PDE) descriptors indicated that the estimated weekly intake of Ni, Cr, and Se from these FSMPs did not exceed the provisional tolerable weekly intake (PTWI) values. However, the highest Ni content was 30.58% of the PTWI, raising concerns about potential health risks, including dermatitis and carcinogenesis. The results for Cr underscored the necessity for careful monitoring due to its potential toxic effects. Selenium, despite its essential role, showed levels inadequate to meet the Recommended Dietary Allowance (RDA), potentially impacting its intended health benefits.

Fertilizer application alters cadmium and selenium bioavailability in soil-rice system with high geological background levels

The co-occurrence of cadmium (Cd) pollution and selenium (Se) deficiency commonly exists in global soils, especially in China. As a result, there is great interest in developing practical agronomic strategies to simultaneously achieve Cd remediation and Se mobilization in paddy soils, thereby enhancing food quality/safety. To this end, we conducted a field-plot trial on soils having high geological background levels of Cd (0.67 mg kg-1) and Se (0.50 mg kg-1). We explored 12 contrasting fertilizers (urea, potassium sulfate (K2SO4), calcium-magnesium-phosphate (CMP)), amendments (manure and biochar) and their combinations on Cd/Se bioavailability. Soil pH, total organic carbon (TOC), soil available Cd/Se, Cd/Se fractions and Cd/Se accumulation in different rice components were determined. No significant differences existed in mean grain yield among treatments. Results showed that application of urea and K2SO4 decreased soil pH, whereas the CMP fertilizer and biochar treatments increased soil pH. There were no significant changes in TOC concentrations. Three treatments (CMP, manure, biochar) significantly decreased soil available Cd, whereas no treatment affected soil available Se at the maturity stage. Four treatments (CMP, manure, biochar and manure＋urea＋CMP＋K2SO4) achieved our dual goal of Cd reduction and Se enrichment in rice grain. Structural equation modeling (SEM) demonstrated that soil available Cd and root Cd were negatively affected by pH and organic matter (OM), whereas soil available Se was positively affected by pH. Moreover, redundancy analysis (RDA) showed strong positive correlations between soil available Cd, exchangeable Cd and reducible Cd with grain Cd concentration, as well as between pH and soil available Se with grain Se concentration. Further, there was a strong negative correlation between residual Cd/Se (non-available fraction) and grain Cd/Se concentrations. Overall, this study identified the primary factors affecting Cd/Se bioavailability, thereby providing new guidance for achieving safe production of Se-enriched rice through fertilizer/amendment management of Cd-enriched soils.

Safety and efficacy of Vitamin C, Vitamin E, and selenium supplementation in the oncology setting: A systematic review

OBJECTIVE

With rising rates of complementary and alternative medicine (CAM) use, the exploration of CAM integration into oncology treatments is becoming increasingly prevalent. Antioxidants have been proposed as potentially beneficial to prevent or treat cancer. However, evidence summaries are limited, and the United States Preventive Services Task Force has recently recommended the use of Vitamin C and E supplementation for cancer prevention. Thus, the objective of this systematic review is to evaluate the existing literature on the safety and efficacy of antioxidant supplementation in oncology patients.

METHODS

A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, using prespecified search terms in PubMed and CINAHL. Two reviewers independently reviewed titles, abstracts, and full-text articles, with a third reviewer resolving conflicts, before the included articles underwent data extraction and quality appraisal.

RESULTS

Twenty-four articles met the inclusion criteria. Of the included studies, nine evaluated selenium, eight evaluated Vitamin C, four evaluated Vitamin E, and three of these studies included a combination of two or more of these agents. The most frequently evaluated cancer types included colorectal cancer (n = 4), leukemias (n = 4), breast cancer (n = 3), and genitourinary cancers (n = 3). Most of the studies focused on the antioxidants' therapeutic efficacy (n = 15) or their use in protecting against chemotherapy- or radiation-induced side effects (n = 8), and one study evaluated the role of an antioxidant in protection against cancer. Findings were generally favorable among the studies, and adverse effects of supplementation were limited. Furthermore, the average score for all the included articles on the Mixed Methods Appraisal Tool was 4.2, indicating the high quality of the studies.

CONCLUSIONS

Antioxidant supplements may provide benefits in reducing incidence or severity of treatment-induced side effects with limited risk for adverse effects. Large, randomized controlled trials are needed to confirm these findings among various cancer diagnoses and stages. Healthcare providers should understand the safety and efficacy of these therapies to address questions that arise in caring for those with cancer.

Comparison of trace elements in peripheral blood and bone marrow of newly diagnosed multiple myeloma patients

Trace elements are essential micronutrients for the human body. Their roles are indispensable, as they are involved in a wide range of vital biological processes. In this study, we aimed to evaluate alterations in trace elements in the blood and bone marrow serum of patients with newly diagnosed multiple myeloma (NMM). The levels of zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), magnesium (Mg), selenium (Se), arsenic (As), boron (B), nickel (Ni), silicon (Si) and chromium (Cr) were analyzed in the venous blood samples of the patient group comprising 70 patients with NMM (41 males and 29 females) and compared to those in the control group comprising 30 individuals (18 males and 12 females). In addition, trace element levels were analyzed in bone marrow samples from the patient group. Blood and bone marrow serum levels were quantified using inductively coupled plasma optical emission spectrometry. When the blood samples of the patient and control groups were compared: Zn (p = 0.011), Fe (p = 0.008), Mn (p = 0.046), Se (p < 0.001), As (p < 0.001), Ni (p < 0.001) and Cr (p < 0.001) levels were significantly higher in the patient group than in the control group. Higher Zn, Fe, Mn, Se, As, Ni and Cr levels in the NMM patients suggest that alterations of trace elements could be predisposing factor that initiates the malignant process. The relationship between malignancies and trace elements is crucial for the development of adjuvant therapy strategies and preventive medicine and as biomarkers for cancer diagnosis. Therefore, there is a need for studies examining the relationship between hematological malignancies and trace elements.

Role of Natural Antioxidants in Cancer

The oxidative stress defined as an event caused by an imbalance between production and accumulation of reactive oxygen species (ROS), which lead to a damage in the structure of proteins, lipids, and DNA. Therefore, the production of ROS may alter the normal physiological process by provoking damage to multiple cellular organelles and processes. Oxidative stress has been linked to heart disease, cancer, respiratory diseases, immune deficiency, stroke, Parkinson's disease, and other inflammatory or ischemic conditions. Antioxidants are substances that can prevent or slow damage to cells and tissues caused by ROS, unstable molecules that the body produces as a reaction to environmental and other pressures. The β-carotene, catechins, flavonoids, polyphenols, lycopene, lutein, selenium, vitamins A, C, D, E, and zeaxanthin are all common types of antioxidants and found in plant-based foods, especially fruits and vegetables. Each antioxidant has its own role and can interact with others to process and remove free radicals efficiently. Several studies have been conducted to investigate whether the use of dietary antioxidant supplements is associated with decreased risks of developing cancer in humans, mixed results were reported. For instance, daily use of supplement such as vitamin c, vitamin E, β-Carotene, and minerals such as selenium and zinc have shown its effectiveness by reducing the risk of developing prostate cancer among men and skin cancer among women.

Selenium - a scoping review for Nordic Nutrition Recommendations 2023

Selenium is an essential trace element in humans, critical to the normal physiology in all animal species. The main form of selenium in food is selenomethionine, selenocysteine and a variety of organic compounds, while inorganic salts mainly occur in food supplements. In animals and humans, selenium occurs as selenocysteine in selenoproteins encoded by 25 genes (specific selenium pool). Several selenoproteins are part of the antioxidant enzyme system and serve as oxido-reductases and in thyroid hormone regulation. SelenoproteinP (SELENOP) transports selenium to peripheral tissues, is the main plasma selenoprotein, and has been used as biomarker of selenium status and intake. SELENOP in plasma represents a saturable pool of selenium and is maximised at a selenium concentration in plasma of about 110 µg/L or an intake of selenomethionine at about 1.2 µg/kg body weight in adults. In Finland, with an estimated selenium intake of 88 µg/day in men and 68 µg/day in women, the average selenium concentration in plasma is about 110 µg/L. Imported wheat from selenium rich areas is an important dietary source in Norway. Dietary intakes in the Nordic and Baltic area vary from 39 to 88 µg/day in men and 22 to 68 µg/day in women, the highest levels were from Finland. Most intervention trials on the effect of selenium supplementation on health outcomes have been carried out in 'selenium-replete'-populations and show no beneficial effect, which from a nutritional point of view would rather not be expected. Some intervention studies conducted in populations low in selenium have showed a beneficial effect. Observational studies suggest an inverse relationship between selenium status and risk of cardiovascular diseases (CVDs), cancer and all-cause mortality, and some other outcomes at low levels of intake (<55 µg/day) or in plasma or serum (<100 µg/L). However, a lack of quantitative data and inconsistencies between studies precludes these studies to be used to derive dietary reference values. At high intakes above 330 to 450 µg/day selenium may cause toxic effects affecting liver, peripheral nerves, skin, nails, and hair. An upper tolerable level (UL) of 255 µg selenium/day in adults was established by EFSA.

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

Selenium is an essential trace metalloid element that is associated with fundamental importance to human health. Our umbrella review aimed to evaluate the quality of evidence, validity, and biases in the relationship between selenium intake and health-related outcomes according to published systematic reviews with pooled data and meta-analyses. Selenium intake is associated with a decreased risk of digestive system cancers, all-cause mortality, depression, and Keshan disease, when in children reduce the risk of Kashin-Beck disease. Additionally, selenium supplementation can improve sperm quality, polycystic ovary syndrome, autoimmune thyroid disease, cardiovascular disease, and infective outcomes. Selenium supplementation also has relationship with a decreased concentration of serum lipids including total cholesterol and very low-density lipoprotein cholesterol. However, no evidence has shown that selenium is associated with better outcomes among patients in intensive care units. Furthermore, selenium intake may be related with a higher risk of type 2 diabetes and non-melanoma skin cancers. Moreover, most of included studies are evaluated as low quality according to our evidence assessment. Based on our study findings and the limited advantages of selenium intake, it is not recommended to receive extra supplementary selenium for general populations, and selenium supplementation should not be continued in patients whose selenium-deficient status has been corrected.

Biofortification of baby leafy vegetables using nutrient solution containing selenium

BACKGROUND

Biofortification of vegetables is an important innovation technique in the horticultural sector. Vegetables can be a vector of different minor elements that have beneficial effects on human health. Selenium (Se) is an important element for human nutrition and plays a significant role in defence mechanisms. The aim of this work was to investigate the effect of Se in the nutrient solutions on the crop biofortification ability, yield, and quality parameters of four baby leafy vegetables destined to the minimally processed industry. Experiments were performed on lamb's lettuce, lettuce, wild rocket, and spinach. These crops were cultivated in the floating systems with nutrient solution enriched with 0, 2.6, 3.9, and 5.2 μmol L-1 Se provided as sodium selenate.

RESULTS

At harvest, Se concentrations, yield, nitrate concentration, sugars, and some mineral elements were measured. Data collected and analyses showed that yield, nitrate, sucrose, and reducing sugars were not affected by Se treatments, even if varied among species. Se concentrations linearly increased in leaves of different species by increasing the Se concentration in the nutrient solution. Rocket was the species with the highest accumulation ability and reached a concentration of 11 μg g-1 fresh weight Se in plants grown with 5.2 μmol L-1 Se.

CONCLUSION

A floating system with Se-enriched nutrient solution is an optimal controlled growing biofortification system for leafy vegetables. The accumulation ability decreased in different species in the order wild rocket, spinach, lettuce, and lamb's lettuce, highlighting a crop-dependent behaviour and their attitude to biofortification. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Serum Essential Elements and Survival after Cancer Diagnosis

In a prospective study, we measured the associations between three serum elements (Se, Zn and Cu) and the prognosis of 1475 patients with four different types of cancer (breast, prostate, lung and larynx) from University Hospitals in Szczecin, Poland. The elements were measured in serum taken after diagnosis and prior to treatment. Patients were followed from the date of diagnosis until death from any cause or until the last follow-up date (mean years of follow-up: 6.0-9.8 years, according to site). Kaplan-Meier curves were constructed for all cancers combined and for each cancer separately. Age-adjusted hazard ratios (HRs) were estimated using Cox regression. The outcome was all-cause mortality. A Se level in the highest quartile was also associated with a reduced mortality (HR = 0.66; 95%CI 0.49-0.88; p = 0.005) in all-cause mortality for all cancers combined. Zn level in the highest quartile was also associated with reduced mortality (HR = 0.55; 95%CI 0.41-0.75; p = 0.0001). In contrast, a Cu level in the highest quartile was associated with an increase in mortality (HR = 1.91; 95%CI 1.56-2.08; p = 0.0001). Three serum elements-selenium, zinc and copper-are associated with the prognosis of different types of cancer.

Different levels of arsenic exposure through cooked rice and its associated benefit-risk assessment from rural and urban populations of West Bengal, India: a probabilistic approach with sensitivity analysis

Rice arsenic (As) contamination and its consumption poses a significant health threat to humans. The present study focuses on the contribution of arsenic, micronutrients, and associated benefit-risk assessment through cooked rice from rural (exposed and control) and urban (apparently control) populations. The mean decreased percentages of As from uncooked to cooked rice for exposed (Gaighata), apparently control (Kolkata), and control (Pingla) areas are 73.8, 78.5, and 61.3%, respectively. The margin of exposure through cooked rice (MoE_{cooked rice}) < 1 signifies the existence of health risk for all the studied exposed and control age groups. The respective contributions of iAs (inorganic arsenic) in uncooked and cooked rice are nearly 96.6, 94.7, and 100% and 92.2, 90.2, and 94.2% from exposed, apparently control, and control areas. LCR analysis for the exposed, apparently control, and control populations (adult male: 2.1 × 10^-3, 2.8 × 10^-4, 4.7 × 10^-4; adult female: 1.9 × 10^-3, 2.1 × 10^-4, 4.4 × 10^-4; and children: 5.8 × 10^-4, 4.9 × 10^-5, 1.1 × 10^-4) through cooked rice is higher than the recommended value, i.e., 1 × 10^-6, respectively, whereas HQ > 1 has been observed for all age groups from the exposed area and adult male group from the control area. Adults and children from rural area showed that ingestion rate (IR) and concentration are the respective influencing factors towards cooked rice As, whereas IR is solely responsible for all age groups from urban area. A vital suggestion is to reduce the IR of cooked rice for control population to avoid the As-induced health risks. The average intake (μg/day) of micronutrients is in the order of Zn > Se for all the studied populations and Se intake is lower for the exposed population (53.9) compared to the apparently control (140) and control (208) populations. Benefit-risk assessment supported that the Se-rich values in cooked rice are effective in avoiding the toxic effect and potential risk from the associated metal (As).

Synthesis of Selenium Nanoparticles Modified by Quaternary Chitosan Covalently Bonded with Gallic Acid

Quaternary chitosan derivative with covalently bonded antioxidant (QCG) was used as media for synthesis of selenium nanoparticles (SeNPs). SeNPs were characterized using AFM, TEM, and DLS methods. The data confirmed the formation of stable nanoparticles with a positive charge (34.86-46.73 mV) and a size in the range 119.5-238.6 nm. The antibacterial and fungicidal activity of SeNPs occurred within the range of values for chitosan derivatives. In all cases, the highest activity was against C. albicans (MIC 125 µg/mL). The toxicity of the modified selenium nanoparticles to eukaryotic cells was significantly higher. Among nanoparticle samples, SeNPs that were synthesized at 55 °C demonstrated the highest toxicity against Colo357 and HaCaT cell lines. Based on these results, SeNPs loaded with doxorubicin were obtained. DOX loading efficiency was about 18%. QCG-SeNPs loaded with DOX at a concentration of 1.25 μg/mL inhibited more than 50% of hepatocarcinoma (Colo 357) cells and about 70% of keratinocytes (HaCaT).

Higher serum selenium concentration is associated with lower risk of all-cause and cardiovascular mortality among individuals with chronic kidney disease: A population-based cohort study of NHANES

Background

Selenium is an essential nutrient and trace element required for human health and plays an important role in antioxidative and anti-inflammatory processes. However, the long-term impact of selenium levels on the health of patients with chronic kidney disease remains unclear.

Method

Participants in this study were 3,063 CKD adults from the Third National Health and Nutrition Examination Survey (NHANES 1999–2000, 2003–2004, and 2011–2018). The mortality status and the cause of death of the study participants were obtained from the National Death Index records. For all-cause and cardiovascular disease (CVD) mortality, the models employed to estimate hazard ratios (HRs) and 95% CI were Cox proportional hazard models and competing risk models, respectively.

Result

During the follow-up period, 884 deaths occurred, including 336 heart-disease-associated deaths. The median (IQR) concentration of serum selenium was 181.7 (156.1, 201.5) μg/L. After full adjustment, serum selenium levels were associated with a decreased risk of mortality in patients with CKD, including all-cause and CVD mortality (P &lt; 0.001). The multivariate-adjusted HRs (95%CI) were 0.684 (0.549–0.852) for all-cause mortality (Ptrend &lt; 0.001) and 0.513 (0.356–0.739) for CVD mortality (Ptrend &lt; 0.001) when selenium concentrations were compared according to the extreme quartiles. Selenium levels are inversely associated with an increased risk of all-cause mortality and CVD mortality. Similar results were observed in subgroup and sensitivity analyses.

Conclusion

Higher serum selenium concentration was independently associated with a decreased risk of all-cause and CVD mortality in patients with CKD.

An Assessment of Serum Selenium Concentration in Women with Ovarian Cancer

BACKGROUND

Available studies on the effect of serum selenium levels on the risk of malignancies show some conflicting results. In this study, we investigated the correlation between serum selenium levels and ovarian cancer occurrence.

METHODS

314 women (157 diseased patients and 157 healthy ones) matched in terms of age and BMI were included in the study. The measurements of selenium in the collected blood samples were performed using an ICP mass spectrometer. Univariable and multivariable analyzes were performed to determine the relationship between the factors under the study and the occurrence of ovarian cancer.

RESULTS

The mean concentration of selenium was lower among diseased ones than among controls (53.31 μg/L vs. 78.99 μg/L). A decrease in selenium concentration was noticed with the advancement of ovarian cancer. In univariable and multivariable analyzes, a clear relationship between low selenium concentration and the occurrence of ovarian cancer was found (35.3 (95% CI: 11.2-111; p < 0.001) and 45.8 (95% CI: 12.8-164; p < 0.001)).

CONCLUSION

The studied patients with ovarian cancer are characterized by statistically significant lower serum selenium levels than patients from the control group. Among the study group, a decrease in selenium concentration was observed with an increase in the FIGO stage. The determination of the role of selenium as a prophylactic factor in ovarian cancer requires further prospective studies.

Research strategies in nutrition in health and disease: The failure of mechanistic research

This paper critically evaluates different research methods in order to assess their value for establishing which dietary changes are most effective for protecting health and preventing disease. The evidence demonstrates that the combined use of observational studies (mainly cohort studies) and randomized controlled trials (RCTs) is the most successful strategy. Studies of the details of body mechanisms in health and disease (mechanistic research) is another commonly used research strategy. However, much evidence demonstrates that it is a far less successful strategy. In order to support the above conclusions research studies from the following areas are discussed: obesity and dietary fat; heart disease and saturated fat; the Mediterranean diet and cardiovascular disease; type 2 diabetes and dietary fiber; and cancer and micronutrients. While mechanistic research has a poor track record in nutrition, it has achieved some success in other areas of biomedical science. This is shown by examining the role of mechanistic research in the discovery of new drugs.

Chelation Combination-A Strategy to Mitigate the Neurotoxicity of Manganese, Iron, and Copper?

The chelating thiol dimercaptosuccinate (DMSA) and the traditional agent D-penicillamine (PSH) are effective in enhancing the urinary excretion of copper (Cu) and lead (Pb) in poisoned individuals. However, DMSA, PSH, EDTA (ethylenediamine tetraacetate), and deferoxamine (DFOA) are water-soluble agents with limited access to the central nervous system (CNS). Strategies for mobilization of metals such as manganese (Mn), iron (Fe), and Cu from brain deposits may require the combined use of two agents: one water-soluble agent to remove circulating metal into urine, in addition to an adjuvant shuttler to facilitate the brain-to-blood mobilization. The present review discusses the chemical basis of metal chelation and the ligand exchange of metal ions. To obtain increased excretion of Mn, Cu, and Fe, early experiences showed promising results for CaEDTA, PSH, and DFOA, respectively. Recent experiments have indicated that p-amino salicylate (PAS) plus CaEDTA may be a useful combination to remove Mn from binding sites in CNS, while the deferasirox-DFOA and the tetrathiomolybdate-DMSA combinations may be preferable to promote mobilization of Fe and Cu, respectively, from the CNS. Further research is requested to explore benefits of chelator combinations.

Long-Term Excessive Selenium Supplementation Affects Gene Expression in Esophageal Tissue of Rats

Esophageal cancer is one of the leading causes of cancer death and the seventh most prevalent cancer worldwide. Considering the positive association of high selenium with the prevalence of esophageal cancer, we have investigated the effect of high doses of selenium on gene expression in the normal esophageal tissue of rats. Twenty male rats were randomly divided into four groups: control group, group 2 mg Se/L, 10 mg Se/L, and 20 mg Se/L rats fed with a basal basic diet and 2, 10, and 20 mg Se/L as sodium selenite in drinking water, respectively, for 20 weeks. Serum malondialdehyde and glutathione peroxidase activity were measured. Moreover, the expression and concentration of the cyclin D1, cyclin E, KRAS, p53, NF-kB, TGF-β, and MGMT in the esophageal tissue were analyzed and compared between the four groups. In normal esophageal tissue, selenium supplementations (2, 10, and 20 mg Se/L) increased the mRNA levels of cyclin D1, P53, KRAS, NF-κB p65, and MGMT and decreased the mRNA level of TGFß1. The concentrations of cyclin D1 and MGMT were also significantly increased by selenium supplementations. Selenium supplementations had no significant effect on serum MDA but significantly increased GPX activity. The present study suggests that selenium supplementation (2, 10, and 20 mg Se/L) affects gene expression related to inflammation, Cell proliferation, and apoptosis in the normal esophageal tissue. However, there were no observed abnormalities other than reduced growth with supplementation of 20 mg/L as Na2SeO3 in rats.

The selenophosphate synthetase family: A review

Selenophosphate synthetases use selenium and ATP to synthesize selenophosphate. This is required for biological utilization of selenium, most notably for the synthesis of the non-canonical amino acid selenocysteine (Sec). Therefore, selenophosphate synthetases underlie all functions of selenoproteins, which include redox homeostasis, protein quality control, hormone regulation, metabolism, and many others. This protein family comprises two groups, SelD/SPS2 and SPS1. The SelD/SPS2 group represent true selenophosphate synthetases, enzymes central to selenium metabolism which are present in all Sec-utilizing organisms across the tree of life. Notably, many SelD/SPS2 proteins contain Sec as catalytic residue in their N-terminal flexible selenium-binding loop, while others replace it with cysteine (Cys). The SPS1 group comprises proteins originated through gene duplications of SelD/SPS2 in metazoa in which the Sec/Cys-dependent catalysis was disrupted. SPS1 proteins do not synthesize selenophosphate and are not required for Sec synthesis. They have essential regulatory functions related to redox homeostasis and pyridoxal phosphate, which affect signaling pathways for growth and differentiation. In this review, we summarize the knowledge about the selenophosphate synthetase family acquired through decades of research, encompassing their structure, mechanism, function, and evolution.

Single and Combined Associations of Plasma and Urine Essential Trace Elements (Zn, Cu, Se, and Mn) with Cardiovascular Risk Factors in a Mediterranean Population

Trace elements are micronutrients that are required in very small quantities through diet but are crucial for the prevention of acute and chronic diseases. Despite the fact that initial studies demonstrated inverse associations between some of the most important essential trace elements (Zn, Cu, Se, and Mn) and cardiovascular disease, several recent studies have reported a direct association with cardiovascular risk factors due to the fact that these elements can act as both antioxidants and pro-oxidants, depending on several factors. This study aims to investigate the association between plasma and urine concentrations of trace elements and cardiovascular risk factors in a general population from the Mediterranean region, including 484 men and women aged 18−80 years and considering trace elements individually and as joint exposure. Zn, Cu, Se, and Mn were determined in plasma and urine using an inductively coupled plasma mass spectrometer (ICP-MS). Single and combined analysis of trace elements with plasma lipid, blood pressure, diabetes, and anthropometric variables was undertaken. Principal component analysis, quantile-based g-computation, and calculation of trace element risk scores (TERS) were used for the combined analyses. Models were adjusted for covariates. In single trace element models, we found statistically significant associations between plasma Se and increased total cholesterol and systolic blood pressure; plasma Cu and increased triglycerides and body mass index; and urine Zn and increased glucose. Moreover, in the joint exposure analysis using quantile g-computation and TERS, the combined plasma levels of Zn, Cu, Se (directly), and Mn (inversely) were strongly associated with hypercholesterolemia (OR: 2.03; 95%CI: 1.37−2.99; p < 0.001 per quartile increase in the g-computation approach). The analysis of urine mixtures revealed a significant relationship with both fasting glucose and diabetes (OR: 1.91; 95%CI: 1.01−3.04; p = 0.046). In conclusion, in this Mediterranean population, the combined effect of higher plasma trace element levels (primarily Se, Cu, and Zn) was directly associated with elevated plasma lipids, whereas the mixture effect in urine was primarily associated with plasma glucose. Both parameters are relevant cardiovascular risk factors, and increased trace element exposures should be considered with caution.

Serum Selenium, Vitamin A, and Vitamin E Levels of Healthy Individuals in High- and Low-Risk Areas of Esophageal Cancer

Background: Esophageal cancer is one of the main causes of cancer mortality in the world. Golestan province, in the northern part of Iran, has the highest esophageal cancer rate in the world. The north and south districts of Golestan province can be classified as low and high-risk areas for esophageal cancer. One of the potential risk factors for esophageal cancer in this population is a nutrient-deficient diet. Dietary antioxidant compounds such as selenium, vitamin E, vitamin A, and β-carotene are reactive oxygen species (ROC) scavengers that play a key role in cellular responses to oxidative stress and preventing DNA damage. This study aims to compare the serum levels of selenium, vitamin E, and vitamin A in healthy individuals in high and low-risk areas of esophageal cancer. Methods: This study is a population of 242 healthy individuals. Serum selenium levels were assessed by atomic absorption spectroscopy. Vitamin E and A were assessed by reversed-phase high-performance liquid chromatography. Results: Vitamin E levels of healthy individuals in high-risk areas were significantly lower than in low-risk areas, while there was no significant difference between the selenium and vitamin A levels of healthy individuals in high-risk areas and low-risk areas. Also, there was no significant difference between selenium, vitamin E, and vitamin A levels in urban and rural areas and men and women in Golestan province. Conclusion: High levels of selenium with lower levels of vitamin E, along with other risk factors, may be associated with esophageal squamous cell carcinoma in high-risk areas of Golestan province.

Association between levels of blood trace minerals and periodontitis among United States adults

Aim

Evidence linking trace minerals and periodontitis is limited. To investigate the relationship between trace minerals (selenium, manganese, lead, cadmium, and mercury) and periodontitis, data from the National Health and Nutrition Examination Survey (NHANES) were analyzed after accounting for potential confounding factors. No known studies have explored the relationship between these five trace minerals and periodontitis.

Materials and methods

A total of 4,964 participants who had undergone a full-mouth periodontal examination and laboratory tests for five trace minerals were studied in a cross-sectional study. Clinical attachment loss (CAL) and periodontitis grading were used to measure periodontitis severity. Linear and logistic regression models were used to evaluate the association between trace minerals and periodontitis. Further subgroup analyses were performed.

Results

Blood lead and cadmium levels were positively associated with mean CAL, and blood selenium was negatively associated with mean CAL; however, blood mercury, blood manganese, and mean CAL were not significantly associated. The association between trace minerals and mean CAL was more significant in males, the elderly, and patients with diabetes. There was a threshold effect between blood cadmium levels and mean CAL. Among the Black population, the relationship between blood cadmium levels and mean CAL followed an inverted U-shaped curve. There was a saturation effect in the study of blood lead in people aged 45–59 years old.

Conclusion

Our study highlighted that blood selenium, lead, and cadmium levels were significantly associated with periodontitis in a nationally representative sample of United States adults.

Selenium and cancer risk: Wide-angled Mendelian randomization analysis

Evidence on the association between selenium and cancer risk is inconclusive. We conducted a Mendelian randomization study to examine the associations of selenium levels with 22 site-specific cancers and any cancer. Single nucleotide polymorphisms (SNPs) strongly associated with toenail and blood (TAB) and blood selenium levels in mild linkage disequilibrium (r2  < .3) were used as instrumental variables. Genetic associations of selenium-associated SNPs with cancer were obtained from the UK Biobank including a total of 59 647 cancer cases and 307 914 controls. Associations with P < .1 in UK Biobank were tested for replication in the FinnGen consortium comprising more than 180 000 individuals. The inverse-variance weighted method accounting for linkage disequilibrium was used to estimate the associations. Genetically predicted TAB selenium levels were not associated with the risk of the 22 site-specific cancers or any cancer (all 22 site-specific cancers). Similarly, we observed no strong association for genetically predicted blood selenium levels. However, genetically predicted blood selenium levels showed suggestive associations with risk of kidney cancer (odds ratio [OR] per one-unit increase in log-transformed levels: 0.83; 95% confidence interval [CI]: 0.67-1.03) and multiple myeloma (OR: 1.40; 95% CI: 1.02-1.93). The same direction of association for kidney cancer but not for multiple myeloma was observed in FinnGen. In the metaanalysis of UK Biobank and FinnGen, the OR of kidney cancer was 0.83 (95% CI: 0.69-1.00). Our study suggests that high selenium status may not prevent cancer development. The associations for kidney cancer and multiple myeloma need to be verified in well-powered studies.

Bioaccessibility and bioavailability of selenium species in Se-enriched leeks (Allium Porrum) cultivated by hydroponically

The Allium genus vegetables are of special interest since being potentially sources for selenium. In this study, the metabolization of selenite and selenate fortification at low and high levels in hydroponically cultivated Allium porrum (Leek) was investigated. The total Se analysis of nutritional solutions which was used in cultivation medium revealed that leeks had potential to accumulate Se above over 1000 mg/kg without any growth disturbance which was proved by comparing dry masses of control group with the ones fortified by Se species. Speciation analyses performed in edible parts which are leaves and stems showed that approximately 90% of total selenium was biotransformed into organo-selenium species in which MeSeCys and SeMet were found to be the most dominant in Se(IV) fortified leeks. However, selenate was found to be the most abundant species in edible parts of selenate fortified leeks especially at high levels. Although bioavailability rate of total selenium in selenate fortified leeks was found to be higher, lower amount of inorganic selenium and higher amount of MeSeCys were found to be bioavailable in Se(IV) fortified.

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.

An Assessment of Serum Selenium Concentration in Women with Endometrial Cancer

Background: Numerous studies have shown a relationship between low serum selenium levels and an increased risk of developing cancer. Methods: A total of 306 women participated in the study: 153 patients diagnosed with endometrial cancer and 153 healthy women who were matched, in terms of birth year (+/−3 years), to the patients from the study group. The quantitative measurement of selenium content in the collected blood samples was performed using a mass spectrometer with excitation in inductively coupled plasma. In order to determine the relationship between the risk factors and the incidence of endometrial cancer, analyses based on single- and multi-factor conditional logistic regression models were performed. Results: The mean concentration of selenium was lower in patients with endometrial cancer than in healthy controls (60.63 µg/L (0.77 µmol/L) vs. 78.74 µg/L (0.99 µmol/L), respectively). When compared in quartiles, a significant association of lower selenium concentration with the incidence of endometrial cancer was recorded. The highest OR was observed in the first and second quartiles (OR-22.0, p-value < 0.001; medium selenium level 46.95 µg/L (0.59 µmol/L), and OR-5.94; p-value < 0.001; medium selenium level 63.60 µg/L (0.80 µmol/L), respectively). Conclusion: A strong correlation between the level of selenium in the blood serum and the risk of endometrial cancer indicates that patients with low levels should be a candidate group requiring appropriate preventive examinations. Further research on a larger group of patients is required.

Selenium Status in Patients with Chronic Liver Disease: A Systematic Review and Meta-Analysis

Background: The potential role of selenium in preventing chronic liver diseases remains controversial. This meta-analysis aimed to summarize the available evidence from observational studies and intervention trials that had evaluated the associations between body selenium status and chronic liver diseases. Methods: We comprehensively searched MEDLINE, Embase, Web of Science, and Cochrane Library from inception to April 2021. The study protocol was registered at PROSPERO (CRD42020210144). Relative risks (RR) for the highest versus the lowest level of selenium and standard mean differences (SMD) with 95% confidence intervals (CI) were pooled using random-effects models. Heterogeneity and publication bias were evaluated using the I² statistic and Egger’s regression test, respectively. Results: There were 50 studies with 9875 cases and 12975 population controls in the final analysis. Patients with hepatitis (SMD = −1.78, 95% CI: −2.22 to −1.34), liver cirrhosis (SMD = −2.06, 95% CI: −2.48 to −1.63), and liver cancer (SMD = −2.71, 95% CI: −3.31 to −2.11) had significantly lower selenium levels than controls, whereas there was no significant difference in patients with fatty liver diseases (SMD = 1.06, 95% CI: −1.78 to 3.89). Moreover, the meta-analysis showed that a higher selenium level was significantly associated with a 41% decrease in the incidence of significant advanced chronic liver diseases (RR = 0.59, 95% CI: 0.49 to 0.72). Conclusion: Our meta-analysis suggested that both body selenium status and selenium intake were negatively associated with hepatitis, cirrhosis, and liver cancer. However, the associations for fatty liver diseases were conflicting and need to be established in prospective trials.

Comparative study of the ameliorative effects of omega-3 versus selenium on etoposide-induced changes in Sertoli cells and ectoplasmic specialization of adult rat testes: immunohistochemical and electron microscopic study

Etoposide (Eto) is an anti-cancer drug that is associated with serious adverse effects on male reproductive function. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) and selenium (Se) are known as anti-inflammatory, anti-apoptotic and anti-oxidant agents. This work was designed to investigate changes in the biochemical parameters as well as alterations in Sertoli cell vimentin expression, ultrastructure and ectoplasmic specializations (ESs) following Eto treatment and to assess the ameliorative effect of ω-3 versus Se on these alterations. Eighty four adult male albino rats were used and classified into four groups: group I (control group), group II (Eto group) received Eto in a single intra-peritoneal (IP) dose (60 mg/kg B.W.), group III (Eto & ω-3 group) received the single IP dose of Eto as well as ω-3 (300 mg/kg B.W./day by intra-gastric intubation) starting 5 days before Eto injection till the time of sacrifice & group IV (Eto & Se group) received the single IP dose of Eto as well as Se (0.5 mg/kg B.W./day IP) starting 5 days before Eto injection till the time of sacrifice. The rats were subdivided into 2 subgroups (a) and (b) that were sacrificed 3 and 7 days after Eto injection respectively. Eto administration in group II induced increase in malondialdehyde (MDA), decrease in superoxide dismutase (SOD), collapse of Sertoli cell vimentin filaments and ultrastructural degenerative changes in both Sertoli cells and ESs. Se (group IV) reversed Eto toxic effects potently, while ω-3 (group III) had some limited protective effects.

The Role of Selenium in Pathologies: An Updated Review

Selenium is an essential microelement required for a number of biological functions. Selenium—and more specifically the amino acid selenocysteine—is present in at least 25 human selenoproteins involved in a wide variety of essential biological functions, ranging from the regulation of reactive oxygen species (ROS) concentration to the biosynthesis of hormones. These processes also play a central role in preventing and modulating the clinical outcome of several diseases, including cancer, diabetes, Alzheimer’s disease, mental disorders, cardiovascular disorders, fertility impairments, inflammation, and infections (including SARS-CoV-2). Over the past years, a number of studies focusing on the relationship between selenium and such pathologies have been reported. Generally, an adequate selenium nutritional state—and in some cases selenium supplementation—have been related to improved prognostic outcome and reduced risk of developing several diseases. On the other hand, supra-nutritional levels might have adverse effects. The results of recent studies focusing on these topics are summarized and discussed in this review, with particular emphasis on advances achieved in the last decade.

Review of Mendelian Randomization Studies on Endometrial Cancer

Endometrial cancer (EC) is a common gynecological cancer. In some parts of the world, the incidence and mortality of EC are on the rise. Understanding the risk factors of EC is necessary to prevent the occurrence of this disease. Observational studies have revealed the association between certain modifiable environmental risk factors and EC risk. However, due to unmeasured confounding, measurement errors, and reverse causality, observational studies sometimes have limited ability to judge robust causal inferences. In recent years, Mendelian randomization (MR) analysis has received extensive attention, providing valuable insights for cancer-related research, and is expected to identify potential therapeutic interventions. In MR analysis, genetic variation (alleles are randomly assigned during meiosis and are usually independent of environmental or lifestyle factors) is used instead of modifiable exposure to study the relationship between risk factors and disease. Therefore, MR analysis can make causal inference about exposure and disease risk. This review briefly describes the key principles and assumptions of MR analysis; summarizes published MR studies on EC; focuses on the correlation between different risk factors and EC risks; and discusses the application of MR methods in EC research. The results of MR studies on EC showed that type 2 diabetes, uterine fibroids, higher body mass index, higher plasminogen activator inhibitor-1 (PAI-1), higher fasting insulin, early insulin secretion, longer telomere length, higher testosterone and higher plasma cortisol levels are associated with increased risk of EC. In contrast, later age of menarche, higher circulatory tumor necrosis factor, higher low-density lipoprotein cholesterol, and higher sex hormone-binding globulin levels are associated with reduced risk of EC. In general, despite some limitations, MR analysis still provides an effective way to explore the causal relationship between different risk factors and EC.

Impact of Selenium on Biomarkers and Clinical Aspects Related to Ageing. A Review

Selenium (Se) is an essential dietary trace element that plays an important role in the prevention of inflammation, cardiovascular diseases, infections, and cancer. Selenoproteins contain selenocysteine in the active center and include, i.a., the enzymes thioredoxin reductases (TXNRD1–3), glutathione peroxidases (GPX1–4 and GPX6) and methionine sulfoxide reductase, involved in immune functions, metabolic homeostasis, and antioxidant defense. Ageing is an inevitable process, which, i.a., involves an imbalance between antioxidative defense and reactive oxygen species (ROS), changes in protein and mitochondrial renewal, telomere attrition, cellular senescence, epigenetic alterations, and stem cell exhaustion. These conditions are associated with mild to moderate inflammation, which always accompanies the process of ageing and age-related diseases. In older individuals, Se, by being a component in protective enzymes, operates by decreasing ROS-mediated inflammation, removing misfolded proteins, decreasing DNA damage, and promoting telomere length. Se-dependent GPX1–4 and TXNRD1–3 directly suppress oxidative stress. Selenoprotein H in the cell nucleus protects DNA, and selenoproteins residing in the endoplasmic reticulum (ER) assist in the removal of misfolded proteins and protection against ER stress. In this review, we highlight the role of adequate Se status for human ageing and prevention of age-related diseases, and further its proposed role in preservation of telomere length in middle-aged and elderly individuals.

The association of minerals intake in three meals with cancer and all-cause mortality: the U.S. National Health and Nutrition Examination Survey, 2003-2014

BACKGROUND

Intake time of diet has recently been demonstrated to be associated with the internal clock and circadian pattern. However, whether and how the intake time of minerals would influence the natural course of cancer was largely unknown.

METHODS

This study aimed to assess the association of mineral intake at different periods with cancer and all-cause mortality. A total of 27,455 participants aged 18-85 years old in the National Health and Nutrition Examination Survey were recruited. The main exposures were the mineral intakes in the morning, afternoon and evening, which were categorized into quintiles, respectively. The main outcomes were mortality of cancer and all causes.

RESULTS

During the 178,182 person-years of follow-up, 2680 deaths, including 601 deaths due to cancer, were documented. After adjusting for potential confounders, compared to the participants who were in the lowest quintile(quintile-1) of mineral intakes at dinner, the participants in the highest quintile intake(quintile-5) of dietary potassium, calcium and magnesium had lower mortality risks of cancer (HRpotassium = 0.72, 95% CI:0.55-0.94, P for trend = 0.023; HRcalcium = 0.74, 95% CI:0.57-0.98, P for trend = 0.05; HRmagnesium = 0.75, 95% CI:0.56-0.99, P for trend = 0.037) and all-cause (HRpotassium = 0.83, 95% CI:0.73-0.94, P for trend = 0.012; HRcalcium = 0.87, 95% CI:0.76-0.99, P for trend = 0.025; HRmagnesium = 0.85, 95% CI:0.74-0.97, P for trend = 0.011; HRcopper = 0.80, 95%CI: 0.68-0.94, P for trend = 0.012). Further, equivalently replacing 10% of dietary potassium, calcium and magnesium consumed in the morning with those in the evening were associated with lower mortality risk of cancer (HRpotassium = 0.94, 95%CI:0.91-0.97; HRcalcium = 0.95, 95%CI:0.92-0.98; HRmagnesium = 0.95, 95%CI: 0.92-0.98).

CONCLUSIONS

This study demonstrated that the optimal intake time of potassium, calcium and magnesium for reducing the risk of cancer and all-cause mortality was in the evening.

The Aging Kidney-As Influenced by Heavy Metal Exposure and Selenium Supplementation

The aging process in the kidneys has been well studied. It is known that the glomerular filtration rate (GFR) declines with age in subjects older than 50–60 years. However, there is still insufficient knowledge regarding the response of the aged kidney to environmental toxicants such as mercury, cadmium, and lead. Here, we present a review on the functional decline and proposed mechanisms in the aging kidney as influenced by metal pollutants. Due to the prevalence of these toxicants in the environment, human exposure is nearly unavoidable. Further, it is well known that acute and chronic exposures to toxic metals may be detrimental to kidneys of normal adults, thus it may be hypothesized that exposure of individuals with reduced GFR will result in additional reductions in renal function. Individuals with compromised renal function, either from aging or from a combination of aging and disease, may be particularly susceptible to environmental toxicants. The available data appear to show an association between exposure to mercury, cadmium and/or lead and an increase in incidence and severity of renal disease in elderly individuals. Furthermore, some physiological thiols, as well as adequate selenium status, appear to exert a protective action. Further studies providing improved insight into the mechanisms by which nephrotoxic metals are handled by aging kidneys, as well as possibilities of therapeutic protection, are of utmost importance.

Selenite Induces Cell Cycle Arrest and Apoptosis via Reactive Oxygen Species-Dependent Inhibition of the AKT/mTOR Pathway in Thyroid Cancer

Thyroid cancer is the most common endocrine malignancy, and its incidence has increased in the past decades. Selenium has been shown to have therapeutic effects against several tumors. However, its role in thyroid cancer and its underlying molecular mechanism remains to be explored. In the present study, we demonstrated that sodium selenite significantly decreased cell viability and induced G0/G1 cell cycle arrest and apoptosis in thyroid cancer cells in a dose-dependent manner. Transcriptomics revealed that sodium selenite induced intracellular reactive oxygen species (ROS) by promoting oxidative phosphorylation. Increased intracellular ROS levels inhibited the AKT/mTOR signaling pathway and upregulated EIF4EBP3. Intracellular ROS inhibition by N-acetylcysteine (NAC) ameliorated the cellular effects of sodium selenite. The in vitro findings were reproduced in xenograft thyroid tumor models. Our data demonstrated that sodium selenite exhibits strong anticancer effects against thyroid cancer cells, which involved ROS-mediated inhibition of the AKT/mTOR pathway. This suggests that sodium selenite may serve as a therapeutic option for advanced thyroid cancer.

Risk of breast cancer in relation to dietary intake of selenium and serum selenium as a marker of dietary intake: a prospective cohort study within The Malmö Diet and Cancer Study

Purpose

Selenium has been suggested to be protective against breast cancer, but the evidence remains inconclusive. Hence, it is important to further examine the potential protective effect. This prospective cohort study investigates pre-diagnostic selenium intake in relation to breast cancer risk. In addition, we analyze serum selenium as a marker of dietary intake.

Methods

This study includes 17,035 women in the Malmö Diet and Cancer cohort. Dietary assessment and serum samples were collected at baseline (1991–1996). During 344,584 person-years of follow-up, 1,427 incident cases were retrieved. Cox regression analysis examined breast cancer risks adjusted for potential confounding factors. In addition, odds ratios (ORs) were estimated for 1186 cases and an equal number of controls in relation to quartiles (Q) of selenium intake and groups consisting of a combination of intake and serum selenium levels.

Results

No overall association between selenium intake, or a combination of intake and serum levels, and breast cancer risk was found. The adjusted relative risk for breast cancer in selenium intake Q4 versus Q1 was 0.96 (0.83–1.12) (P_trend = 0.65). Similarly, adjusted the OR for breast cancer in selenium intake for Q4 versus Q1 was 0.97 (0.76–1.23). The kappa value, 0.096 (p = 0.001), showed poor agreement between serum selenium and selenium intake.

Conclusion

Our findings suggest that there is no overall association between selenium intake, or a combination of intake and serum levels, and breast cancer risk. Finally, our results showed a poor correlation between estimated selenium intake and serum selenium.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10552-021-01433-1.

Medicinal Prospects of Antioxidants From Algal Sources in Cancer Therapy

Though cancer therapeutics can successfully eradicate cancerous cells, the effectiveness of these medications is mostly restricted to several deleterious side effects. Therefore, to alleviate these side effects, antioxidant supplementation is often warranted, reducing reactive species levels and mitigating persistent oxidative damage. Thus, it can impede the growth of cancer cells while protecting the normal cells simultaneously. Moreover, antioxidant supplementation alone or in combination with chemotherapeutics hinders further tumor development, prevents chemoresistance by improving the response to chemotherapy drugs, and enhances cancer patients' quality of life by alleviating side effects. Preclinical and clinical studies have been revealed the efficacy of using phytochemical and dietary antioxidants from different sources in treating chemo and radiation therapy-induced toxicities and enhancing treatment effectiveness. In this context, algae, both micro and macro, can be considered as alternative natural sources of antioxidants. Algae possess antioxidants from diverse groups, which can be exploited in the pharmaceutical industry. Despite having nutritional benefits, investigation and utilization of algal antioxidants are still in their infancy. This review article summarizes the prospective anticancer effect of twenty-three antioxidants from microalgae and their potential mechanism of action in cancer cells, as well as usage in cancer therapy. In addition, antioxidants from seaweeds, especially from edible species, are outlined, as well.

Electroplating Kinetic of Nanostructured Selenium Films from Citrate Bath

In this work; Cyclic-Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were used to study the electrodeposition kinetic of selenium films in potentiostatic mode from aqueous solution containing selenium dioxide and sodium citrate at pH = 4.2. Semiconducting proprieties of obtained deposits were investigated by Mott-Schottky measurements whereas the optical ones were performed by UV–Visible spectrophotometry. The morphological characterization was carried out using the scanning electron microscopy (SEM). The obtained results showed that the electrodeposition process of selenium films in citrate bath occurred under diffusional regime as rate-limiting step. Deposition rate of selenium layers on platinum substrate is much superior than in the case of ITO substrate and up to a value of 0.65 μg/cm² s. The HSeO₃⁻/Se system becomes more rapid with the increase of the bath temperature. Obtained deposits are photoactive films that belong to p-type semiconductors with number of charge carriers in order of 10²¹/cm³ and energy band gap about 1.7 eV. The grains of electroplated films have spherical forms, nanometric sizes and strong adhesion on the substrate surface.

Dietary Antioxidant Vitamins and Minerals and Breast Cancer Risk: Prospective Results from the SUN Cohort

There is growing interest in natural antioxidants and their potential effects on breast cancer (BC). Epidemiological evidence, however, is inconsistent. We prospectively evaluated the association between dietary intake of vitamins A, C, and E, selenium, and zinc and BC among 9983 female participants from the SUN Project, a Mediterranean cohort of university graduates. Participants completed a food frequency questionnaire at baseline, and biennial follow-up information about incident BC diagnosis was collected. Cases were ascertained through revision of medical charts and consultation of the National Death Index. Cox proportional hazards models were used to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CI). During an average follow-up of 11.3 years, 107 incident BC cases were confirmed. The multivariable HRs (95% CI) for BC comparing extreme tertiles of energy-adjusted dietary intakes were 1.07 (0.64–1.77; P_trend = 0.673) for vitamin A, 1.00 (0.58–1.71; P_trend = 0.846) for vitamin C, 0.92 (0.55–1.54; P_trend = 0.728) for vitamin E, 1.37 (0.85–2.20; P_trend = 0.135) for selenium, and 1.01 (0.61–1.69; P_trend = 0.939) for zinc. Stratified analyses showed an inverse association between vitamin E intake and postmenopausal BC (HR_{T3 vs. T1} = 0.35; 95% CI, 0.14–0.86; P_trend = 0.027). Our results did not suggest significant protective associations between dietary vitamins A, C, and E, selenium, or zinc and BC risk.

Age-adjusted mortality from pancreatic cancer increased NINE-FOLD in japan from 1950 to 1995 - Was a low-protein quasi-vegan diet a key factor in their former low risk?

During the last half of the twentieth century, age-adjusted mortality from pancreatic cancer in Japan rose about nine-fold in both sexes. Well-characterized risk factors such as smoking, obesity/metabolic syndrome, and heavy alcohol use appear to explain only a modest part of this rise. It is proposed that a diet relatively low in protein, and particularly low in animal protein, was a key determinant of the low risk for pancreatic cancer in mid-century Japan. It is further proposed that pancreatic acinar cells, owing to their extraordinarily high rate of protein synthesis, are at high risk for ER stress; that such stress plays a fundamental role in the induction of most pancreatic cancers; and that low-protein diets help to offset such stress by modulating activities of the kinases GCN2 and mTORC1 while increasing autocrine and systemic production of fibroblast growth factor 21. This model appears to clarify the role of various risk factors and protective factors in pancreatic cancer induction. A vegan or quasi-vegan low-protein diet may have broader potential for decreasing risk for a range of common "Western" cancers.

The rationale for selenium supplementation in inflammatory bowel disease: A mechanism-based point of view

Management of inflammatory bowel disease (IBD) has always been a challenge for physicians. Current treatment protocols may cause numerous adverse effects. Selenium is known for its putative antiinflammatory properties. Selenium is needed for the biosynthesis of enzymatically active selenoproteins, which contribute to antioxidative defense, and effective function of immune systems. Several studies have shown that patients with IBD have a lower selenium level compared to healthy subjects. Hence, experimental studies mimicking ulcerative colitis and Crohn's disease investigated the effect of selenium supplementation on IBD. Previous studies indicated the following: 1) Selenoproteins can curb the inflammatory response and attenuate oxidative stress. This antiinflammatory property caused remission in animal models of colitis. 2) Selenium supports protective gut microbiota, which indirectly improves management of IBD. 3) Selenium may block some of the predominant tumorigenesis pathways proposed in colitis-associated colorectal cancer. 4) Selenium supplementation showed promising results in preliminary clinical studies, particularly in patients with selenium deficiency. While selenium supplementation seems to be beneficial for IBD, clinical studies have remained too preliminary in this regard. Randomized clinical trials are needed to measure the short-term and long-term effects of selenium on both active and quiescent IBD, particularly in patients with IBD who have documented selenium deficiency.

Nano-selenium Supplementation Increases Selenoprotein (Sel) Gene Expression Profiles and Milk Selenium Concentration in Lactating Dairy Cows

Supplementation with selenium is common for dairy cows, but the importance of selenium source is not clear. This study aimed to compare nano-selenium (Nano-Se) and sodium selenite supplements for dairy cows on lactation performance, milk Se levels and selenoprotein (Sel) gene expression. Twelve multiparous Holstein cows were randomly divided into two groups: a control group fed a basal diet plus 0.30 mg Se/kg of DM as sodium selenite or Nano-Se for 30 days. Dry matter intake, milk yield and composition were not affected by dietary Se source (P > 0.05); however, the milk total Se levels and milk glutathione peroxidase (GSH-Px) activities were higher with Nano-Se supplementation than sodium selenite (P < 0.05). At the end of the experiment, Nano-Se supplementation significantly increased plasma Se levels and GSH-Px activity, compared with the sodium selenite supplement. The mRNA expression levels of glutathione peroxidase 1, 2 and 4; thioredoxin reductase 2 and 3; and selenoproteins W, T, K and F were markedly upregulated (P < 0.05) in the mammary gland of the Nano-Se group. Thus, the source of selenium plays an important role in the antioxidant status and in particular the Sel gene expression in the mammary glands of dairy cows, both being stimulated by nano sources.

Essential trace elements in Norwegian obese patients before and 12 months after Roux-en-Y gastric bypass surgery: Copper, manganese, selenium and zinc

OBJECTIVES

The objective of the present study was to assess trace element status in morbidly obese subjects before and one year after Roux-en-Y gastric bypass (RYGB) in order to identify possible deficiencies.

METHODS

The study population included 46 patients in the age range 27-59 years, the majority (85 %) were women. The enrolled patients attended an eight week course on lifestyle changes before bariatric surgery. After RYGB they were recommended daily micronutrient supplements with a commonly used multivitamin-mineral tablet in addition to intramuscular vitamin B₁₂ injections (1 mg) every third month for 12 months. Whole blood concentrations of Cu, Mn, Se and Zn were determined using high resolution inductively coupled plasma mass spectrometry.

RESULTS

During the 12 months follow up after bariatric surgery, the patients had lost mean 32.3 kg and median whole blood concentrations of Cu (-16 %) were reduced, Mn (+14 %) and Zn (+6%) were increased, while the Se values were essentially unchanged. Compared with reference ranges, median postoperative concentrations of all essential trace elements were either below (Zn) or in the lower reference range (Cu, Mn, Se).

CONCLUSION

Essential trace elements were below or in the lower reference range twelve months after RYGB. Our results indicate a need for updated guidelines in Nordic countries for trace metal monitoring and supplements in patients after bariatric surgery, especially when gastric bypass surgery is used. Further studies are required to explore and prevent trace element deficiency related to obesity and bariatric surgery.

Current Biomedical Use of Copper Chelation Therapy

Copper is an essential microelement that plays an important role in a wide variety of biological processes. Copper concentration has to be finely regulated, as any imbalance in its homeostasis can induce abnormalities. In particular, excess copper plays an important role in the etiopathogenesis of the genetic disease Wilson's syndrome, in neurological and neurodegenerative pathologies such as Alzheimer's and Parkinson's diseases, in idiopathic pulmonary fibrosis, in diabetes, and in several forms of cancer. Copper chelating agents are among the most promising tools to keep copper concentration at physiological levels. In this review, we focus on the most relevant compounds experimentally and clinically evaluated for their ability to counteract copper homeostasis deregulation. In particular, we provide a general overview of the main disorders characterized by a pathological increase in copper levels, summarizing the principal copper chelating therapies adopted in clinical trials.

Assessing the Role of Selenium in Endometrial Cancer Risk: A Mendelian Randomization Study

Endometrial cancer is the most commonly diagnosed gynecological cancer in developed countries. Based on evidence from observational studies which suggest selenium inhibits the development of several cancers (including lung and prostate cancer), selenium supplementation has been touted as a potential cancer preventative agent. However, randomized controlled trials have not reported benefit for selenium supplementation in reducing cancer risk. For endometrial cancer, limited observational studies have been conducted assessing whether selenium intake, or blood selenium levels, associated with reduced risk, and no randomized controlled trials have been conducted. We performed a two-sample Mendelian randomization analysis to examine the relationship between selenium levels (using a composite measure of blood and toenail selenium) and endometrial cancer risk, using summary statistics for four genetic variants associated with selenium levels at genome-wide significance levels (P < 5 × 10⁻⁸), from a study of 12,906 endometrial cancer cases and 108,979 controls, all of European ancestry. Inverse variance weighted (IVW) analysis indicated no evidence of a causal role for selenium levels in endometrial cancer development (OR per unit increase in selenium levels Z-score = 0.99, 95% CI = 0.87–1.14). Similar results were observed for sensitivity analyses robust to the presence of unknown pleiotropy (OR per unit increase in selenium levels Z-score = 0.98, 95% CI 0.89–1.08 for weighted median; OR per unit increase in selenium levels Z-score = 0.90, 95% CI = 0.53–1.50 for MR-Egger). In conclusion, these results do not support the use of selenium supplementation to prevent endometrial cancer.