Selenium-enriched durum wheat improves the nutritional profile of pasta without altering its organoleptic properties

Selenium in bread wheat (Triticum aestivum L.) grown in Buenos Aires, Argentina

BACKGROUND

Selenium (Se) is an essential micronutrient for humans, but little information is available on its nutritional status in the Argentine population.

OBJECTIVE

The aim of this study is to obtain reliable and representative data on Se content in bread wheat (Triticum aestivum L.) from the Buenos Aires province.

METHODS

The content of the micronutrient Se was determined in 242 samples of bread wheat grains (Triticum aestivum L.) from 75 districts in Buenos Aires, Argentina (representing 75 % of the wheat-producing districts in the province). Se determination was carried out by atomic absorption with hydride generation.

RESULTS

The Se content varied across the districts; in some of them, the Se levels were below the LOD (10 µg kg-1), while the highest content found was around 114 µg kg-1. The average content ( ± standard deviation) of Se in the analyzed grains was 29.90 ( ± 51.30) µg kg-1. This concentration is considered marginal or deficient according to various authors. It reflects both a low contribution of Se to diets and its low bioavailability in soils.

CONCLUSION

Further research on the Se nutritional status of the population is needed. So far, existing studies suggest a sub-optimal nutritional status, and regarding the Se content of wheat grown in Buenos Aires, it seems to be lower than the minimum recommended to maintain an adequate nutritional status through the consumption of dry plant foods. If these results are confirmed, it would be appropriate to implement strategic policies to promote the increase of Se consumption by the population. Fertilisation of wheat crops is recommended because it is a sure way to increase the Se content in the whole food chain.

Effects of Sodium Selenite on Accumulations of Selenium and GABA, Phenolic Profiles, and Antioxidant Activity of Foxtail Millet During Germination

This study investigated the influence of soaking and spraying with a sodium selenite (Na2SeO3) solution on selenium accumulation, γ-aminobutyric acid (GABA) content, phenolic compositions, and the antioxidant activity of foxtail millet sprouts. The screening results showed that foxtail millet seeds soaked with 60 mg/L of Na2SeO3 solution and sprayed with 2 mg/L of Na2SeO3 solution were the appropriate concentrations for the germination process. Compared with the spraying method, a presoaking treatment presented far higher selenium content and significantly higher (p < 0.05) selenium enrichment rates in foxtail millet sprouts. The content of free and bound phenolics, as well as GABA, were significantly (p < 0.05) increased in foxtail millet sprouts through both soaking and spraying treatments. Correspondingly, most of the individual phenolic compounds were significantly (p < 0.05) increased, especially after germination for 3 days. Trans-ferulic acid and trans-p-coumaric acid were the predominate bound phenolic acids, feruloylquinic acid and 4-p-coumaroylquinic acid were the major free-form phenolic compounds, and N-feruloyl serotonin and N-(p-coumaroyl) serotonin were the new arising phenolic derivatives caused by germination. Both the soaking and spraying treatments induced the enrichment of these individual phenolic compositions, thus increasing the total phenolic content and in vitro antioxidant activity of foxtail millet sprouts. It was indicated that selenium-enriched germination treatment should be an effective method to produce functional selenium-enriched foxtail millet sprouts with more abundant GABA and polyphenols, thus enhancing the health benefits and added value of foxtail millet.

Prospects for mineral biofortification of wheat: classical breeding and agronomy

Low intake of micro- and macroelements and vitamins in food negatively affects the health of more than two billion people around the world provoking chronic diseases. For the majority of the world's population, these are soft and durum wheats that provide beneficial nutrients, however their modern high-yielding varieties have a significantly depleted grain mineral composition that have reduced mineral intake through food. Biofortification is a new research trend, whose main goal is to improve the nutritional qualities of agricultural crops using a set of classical (hybridization and selection) methods as well and the modern ones employing gene/QTL mapping, bioinformatic analysis, transgenesis, mutagenesis and genome editing. Using the classical breeding methods, biofortified varieties have been bred as a part of various international programs funded by HarvestPlus, CIMMYT, ICARDA. Despite the promise of transgenesis and genome editing, these labor-intensive methods require significant investments, so these technologies, when applied to wheat, are still at the development stage and cannot be applied routinely. In recent years, the interest in wheat biofortification has increased due to the advances in mapping genes and QTLs for agronomically important traits. The new markers obtained from wheat genome sequencing and application of bioinformatic methods (GWAS, meta-QTL analysis) has expanded our knowledge on the traits that determine the grain mineral concentration and has identified the key gene candidates. This review describes the current research on genetic biofortification of wheat in the world and in Russia and provides information on the use of cultivated and wild-relative germplasms to expand the genetic diversity of modern wheat varieties.

Effect of Selenium-Enriched Substrate on the Chemical Composition, Mineral Bioavailability, and Yield of Edible Mushrooms

Mushrooms absorb minerals from substrates in which they are cultivated, so they could be used as vehicles of minerals that are deficient in human or animal diets, such as selenium. Selenium deficiency aggravates cardiovascular diseases, diabetes mellitus, and intestinal cancer. This work presents the latest discoveries related to the production of edible mushrooms in selenium-enriched substrates and discusses their use as an alternative to supply the deficiency of this mineral in human and animal diets. Selenized mushrooms and their derived extracts present bioaccessible and bioavailable forms of selenium, as antioxidant and antitumor activity, as demonstrated in various in vitro and in vivo experiments. Consequently, the consumption of these mushrooms reduces the levels of blood cholesterol and glucose. On the other hand, growing mushrooms in selenium-enriched substrates may alter the yield and their chemical composition, and this lack of standardization is still an obstacle to the scale up of the production process. On the other hand, the use of agro-industrial by-products as substrates can enable the cultivation of enriched edible mushrooms and their commercialization.

Factors Affecting the Nutritional, Health, and Technological Quality of Durum Wheat for Pasta-Making: A Systematic Literature Review

Durum wheat is one of the most important food sources in the world, playing a key role in human nutrition, as well as in the economy of the different countries in which its production areas are concentrated. Its grain also represents a staple and highly versatile ingredient in the development of health foods. Nonetheless, the aspects determining durum wheat's health quality and their interactions are many, complex, and not entirely known. Therefore, the present systematic literature review aims at advancing the understanding of the relationships among nutritional, health, and technological properties of durum wheat grain, semolina, and pasta, by evaluating the factors that, either positively or negatively, can affect the quality of the products. Scopus, Science Direct, and Web of Science databases were systematically searched utilising sets of keywords following the PRISMA guidelines, and the relevant results of the definitive 154 eligible studies were presented and discussed. Thus, the review identified the most promising strategies to improve durum wheat quality and highlighted the importance of adopting multidisciplinary approaches for such purposes.

Screening of Durum Wheat Cultivars for Selenium Response under Contrasting Environments, Based on Grain Yield and Quality Attributes

In the literature, little information is available on the effect of Selenium (Se) on durum wheat yield and grain quality performances. A field investigation was conducted to explore the effect of exogenous Se foliar supply on two types of durum wheat germplasm; i.e., 16 advanced lines and nine modern varieties. The Se effect was assessed on grain yield as well as on technological quality traits (moisture, protein and gluten contents, Zeleny sedimentation index, and deformation energy) in two contrasting environments in Tunisia, namely Kef–Boulifa (semi-arid region) and Beja (sub-humid region). The results displayed significant effects of environments, Se foliar application, and cultivars on grain yield and quality attributes. For grain yield performance, the beneficial effect of Se was more pronounced under the Kef–Boulifa environment, and conversely for the grain quality. A genetic variation was observed within and among the two environments under both Se treatments (with and without Se). Notably, the Se-treated advanced lines displayed the highest grain yield under Kef–Boulifa and Beja conditions. Although these cultivars showed better grain quality in both sites, the modern varieties valorized the Se foliar application better. Cultivars that recorded the highest values for the studies attributes were not necessarily those that valorized the Se supply better. Interestingly, some advanced lines have noted superiority compared to the modern varieties. In this study, cultivars that combine both good yield and good grain quality were determined for semi-arid (L11, L1, Dhahbi, and Maali) and sub-humid (L2, L14, L6, L3, Salim, and INRAT 100) zones. The screening results provide genetic material that could be exploited in breeding programs to improve Se use efficiency.

Effect of selenium biofortification on bioactive compounds and antioxidant activity in germinated black soybean

Biofortification using inorganic selenium has become an effective strategy to enhance selenium content in crops. In the present study, the effects of selenium biofortification on the chemical composition and antioxidant capacity of black soybean (BS) during germination were studied. The contents of selenium, total sugar, vitamin C, γ-aminobutyric acid, total polyphenols, and total flavonoids in selenium biofortified germinated black soybeans (GBS-Se) significantly increased compared to germinated black soybeans (GBS). However, the contents of soluble protein, fat, and reducing sugar were decreased, while fatty acid composition was not significantly different between GBS and BS. HPLC analysis showed that 12 phenolic acids of all samples, which mainly existed in free forms. Their contents increased at low concentration of selenium and decreased along with the rise of selenium concentrations. The antioxidant activity of GBS-Se as analyzed by Pearson correlation analysis positively correlated with the accumulation of phenolic substances. Principal component analysis (PCA) showed that GBS and GBS-Se were significantly different from BS. Moreover, the physicochemical indexes of GBS showed regularly changes with increasing selenium content, and those of GBS-Se50 and GBS-Se75 were significantly different from GBS. The results provide a systematic evaluation on the effect of selenium fortification on the germination of seeds and useful information for the development of Se-enriched functional foods. PRACTICAL APPLICATION: The organic selenium black soybean (BS) produced by the germination method can be directly processed and eaten to improve human health. In addition, complexes of organic selenium, vitamin C, and γ-aminobutyric acid of germinated BS can be developed into functional substances and applied to food or health products as functional ingredient and/or natural antioxidant supplements.

Selenium in Wheat from Farming to Food

Selenium (Se) plays an important role in human health. Approximately 80% of the world's population does not consume enough Se recommended by the World Health Organization. Wheat is an important staple food and Se source for most people in the world. This review summarizes literature about Se from 1936 to 2020 to investigate Se in wheat farming soil, wheat, and its derived foods. Se fortification and the recommended Se level in wheat were also discussed. Results showed that Se contents in wheat farming soil, grain, and its derived foods around the world were 3.8-552 μg kg^-1 (mean of 220.99 μg kg^-1), 0-8270 μg kg^-1 (mean of 347.30 μg kg^-1), and 15-2372 μg kg^-1 (mean of 211.86 μg kg^-1), respectively. Adopting suitable agronomic measures could effectively realize Se fortification in wheat. The contents in grain, flour, and its derived foods could be improved from 93.94 to 1181.92 μg kg^-1, from 73.06 to 1007.75 μg kg^-1, and from 86.90 to 587.61 μg kg^-1 on average after leaf Se fertilizer application in the field. There was a significant positive correlation between the Se content in farming soil and grain, and it was extremely the same between the foliar Se fertilizer concentration rate and the grain Se increased rate. The recommended Se fortification level in cultivation of wheat in China, India, and Spain was 18.53-23.96, 2.65-3.37, and 3.93-9.88 g hm^-2, respectively. Milling processing and food type could greatly affect the Se content of wheat-derived food and should be considered seriously to meet people's Se requirement by wheat.

Influence of Drought and Salt Stress on Durum Wheat Grain Quality and Composition: A Review

Durum wheat is a staple crop for the Mediterranean diet because of its adaptability to environmental pressure and for its large use in cereal-based food products, such as pasta and bread, as a source of calories and proteins. Durum wheat whole grains are also highly valued for their peculiar amount of dietary fiber and minerals, as well as bioactive compounds of particular interest for their putative health-beneficial properties, including polyphenols, carotenoids, tocopherols, tocotrienols, and phytosterols. In Mediterranean environments, durum wheat is mostly grown under rainfed conditions, where the crop often experiences environmental stresses, especially water deficit and soil salinity that may induce a hyperosmotic stress. In particular, changes in C and N accumulation due to these abiotic conditions, during grain filling, can influence starch and storage protein amount and composition in durum wheat caryopsis, thus influencing yield and quality traits. Recent advancements regarding the influence of water deficit and salinity stress on durum wheat are critically discussed. In particular, a focus on stress-induced changes in (a) grain protein content and composition in relation to technological and health quality; (b) starch and dietary fiber accumulation and composition; (c) phytochemical composition; (d) health-related grain micronutrient accumulation, such as Fe and Zn.

Agronomic Strategies to Improve N Efficiency Indices in Organic Durum Wheat Grown in Mediterranean Area

Organic farming systems are often constrained by limited soil nitrogen (N) availability. Here we evaluated the effect of foliar organic N and sulphur (S), and selenium (Se) application on durum wheat, considering N uptake, utilization efficiency (NUtE), grain yield, and protein concentration as target variables. Field trials were conducted in 2018 and 2019 on two old (Cappelli and old Saragolla) and two modern (Marco Aurelio and Nadif) Italian durum wheat varieties. Four organic fertilization strategies were evaluated, i.e., the control (CTR, dry blood meal at sowing), the application of foliar N (CTR + N) and S (CTR + S), and their joint use (CTR + NS). Furthermore, a foliar application of sodium selenate was evaluated. Three factors-variety, fertilization strategies and selenium application-were arranged in a split-split-plot design and tested in two growing seasons. The modern variety Marco Aurelio led to the highest NUtE and grain yield in both seasons. S and N applications had a positive synergic effect, especially under drought conditions, on pre-anthesis N uptake, N translocation, NUtE, and grain yield. Se treatment improved post-anthesis N uptake and NUtE, leading to 17% yield increase in the old variety Cappelli, and to 13% and 14% yield increase in Marco Aurelio and Nadif, mainly attributed to NUtE increase. This study demonstrated that the synergistic effect of foliar applications could improve organic durum wheat yields in Mediterranean environments, especially on modern varieties.

Selenium Biofortification Modulates Plant Growth, Microelement and Heavy Metal Concentrations, Selenium Uptake, and Accumulation in Black-Grained Wheat

In Se-deficient populations, Selenium- (Se-) enriched wheat is a source of Se supplementation, and Se content can be improved by agronomic biofortification. Thus, black-grained wheat (BGW) and white-grained wheat (WGW) (as the control) were grown in Se naturally contained soils at different concentrations (11.02, 2.21, 2.02, and 0.20 mg·kg-1). Then, a field experiment was conducted to assess agronomic performance, the concentration of microelements and heavy metals, and the uptake and distribution of Se in the BGW under the application of Se ore powder. The results showed that the grain yield and grain Se concentration of wheat respectively show a significant increase and decrease from high Se to low Se areas. Higher grain yield and crude protein content were observed in Se-rich areas. The soil application of Se ore powder increased wheat grain yield and its components (biomass, harvest index, grain number, and 1,000 kernels weight). The concentrations of Zn, Fe, Mn, total Se, and organic Se in the grains of wheat were also increased, but Cu concentration was decreased. The concentrations of Pb, As, Hg, and Cr in wheat grains were below the China food regulation limits following the soil application of Se ore powder. Compared with the control, Se ore powder treatment increased the uptake of Se in various parts of wheat plants. More Se accumulation was observed in roots following Se ore powder application, with a smaller amount in grains. In addition, compared with the control, BGW had significantly higher concentrations of Zn, Fe, and Mn and accumulated more Se in grains and shoots and less Se in roots. The results indicate that wheat grown in Se-rich areas increases its grain yield and crude protein content. The soil application of Se ore powder promotes wheat growth and grain yield. Compared with WGW, BGW accumulated more Se in grains and had a higher concentration of organic Se in grains. In conclusion, the application of Se ore powder from Ziyang as Se-enriched fertilizer could be a promising strategy for Se biofortification in the case of wheat, and BGW is the most Se-rich potential genotype.

Selenium in cereals: Insight into species of the element from total amount

Selenium (Se) is a trace mineral micronutrient essential for human health. The diet is the main source of Se intake. Se-deficiency is associated with many diseases, and up to 1 billion people suffer from Se-deficiency worldwide. Cereals are considered a good choice for Se intake due to their daily consumption as staple foods. Much attention has been paid to the contents of Se in cereals and other foods. Se-enriched cereals are produced by biofortification. Notably, the gap between the nutritional and toxic levels of Se is fairly narrow. The chemical structures of Se compounds, rather than their total contents, contribute to the bioavailability, bioactivity, and toxicity of Se. Organic Se species show better bioavailability, higher nutritional value, and less toxicity than inorganic species. In this paper, we reviewed the total content of Se in cereals, Se speciation methods, and the biological effects of Se species on human health. Selenomethionine (SeMet) is generally the most prevalent and important Se species in cereal grains. In conclusion, Se species should be considered in addition to the total Se content when evaluating the nutritional and toxic values of foods such as cereals.

Insights into uptake, accumulation, and subcellular distribution of selenium among eight wheat (Triticum aestivum L.) cultivars supplied with selenite and selenate

Selenium (Se)-enriched wheat can be improved by altering Se sources and selecting wheat cultivars. Such improvement can affect subcellular distribution and speciation of Se in wheat. Thus, a pot experiment was conducted to investigate Se uptake and distribution when Se was applied as selenite or selenate at low and high rates (1 and 10 mg kg^-1, respectively). Moreover, Se's impact on the grain and biomass yield of eight wheat cultivars was also investigated. The subcellular distribution and speciation of Se were also explored to elucidate Se metabolism and micro-distribution pattern in wheat. Results showed that biomass and grain yield were decreased with the application of both selenite and selenate in almost all the cultivars, regardless of the Se rate. Application high Se rate resulted in a significant (p < 0.05) decrease in grain yield and biomass compared with low rate of Se. Compared with the low rate of selenite application, the grain and the biomass yield of ZM-9023 significantly (p < 0.05) increased by about 15% for low rate of selenate application. In addition, both selenite and selenate treatment increased the uptake of Se in each part of wheat, compared with the control. Selenium was mostly accumulated in the grain and root of wheat under selenite treatment, while more Se accumulation was found in leaves and straw for selenate application. Further investigation on the subcellular distribution of Se showed that the proportion of Se in soluble fraction was significantly (p < 0.05) higher in wheat leaves than that in organelle fraction and cell walls (46%-66%). Meanwhile, Se⁶⁺ was the main species found in soluble fraction, whereas SeMet and MeSeCys were the species predominantly stored in organelle fraction. In conclusion, wheat cultivar ZM-9023 is the most Se-rich potential cultivar, and the isolation of Se in the soluble fraction plays an important role in Se tolerance and accumulation.

Selenium and Nano-Selenium Biofortification for Human Health: Opportunities and Challenges

Selenium is an essential micronutrient required for the health of humans and lower plants, but its importance for higher plants is still being investigated. The biological functions of Se related to human health revolve around its presence in 25 known selenoproteins (e.g., selenocysteine or the 21st amino acid). Humans may receive their required Se through plant uptake of soil Se, foods enriched in Se, or Se dietary supplements. Selenium nanoparticles (Se-NPs) have been applied to biofortified foods and feeds. Due to low toxicity and high efficiency, Se-NPs are used in applications such as cancer therapy and nano-medicines. Selenium and nano-selenium may be able to support and enhance the productivity of cultivated plants and animals under stressful conditions because they are antimicrobial and anti-carcinogenic agents, with antioxidant capacity and immune-modulatory efficacy. Thus, nano-selenium could be inserted in the feeds of fish and livestock to improvise stress resilience and productivity. This review offers new insights in Se and Se-NPs biofortification for edible plants and farm animals under stressful environments. Further, extensive research on Se-NPs is required to identify possible adverse effects on humans and their cytotoxicity.

Understanding boosting selenium accumulation in Wheat (Triticum aestivum L.) following foliar selenium application at different stages, forms, and doses

There are a lack of systematic studies comparing the effects of foliar-applied selenium (Se) with different Se sources at different growth stages in wheat. Herein, we biofortified wheat via the foliar application of selenite and selenate at different rates and different stages under field conditions. Results showed that foliar-applied selenate and selenite had no significant effect either on wheat biomass or grain yield (p < 0.05). Selenium distribution in different parts of wheat plant ranked decrease as leaf > root > grain > glume > stem with selenite treatment, and it appeared in the decline order as leaf > grain > glume > stem > root with selenate treatment. These results suggested that biofortification with selenate caused, relatively to selenite, a higher accumulation of Se in grains. Foliar application of Se of either selenate or selenite at pre-filling stage was superior in improving the Se concentration of wheat grains than application at pre-flowering stage. Meanwhile, organic Se comprised about 72-93% of total Se in wheat grains, which was reduced by 5.8% at high Se rate (100 g ha^-1), irrespective of the forms of Se or stages applied. The organic Se proportion in wheat grains was 9% higher with the selenate treatment than with the selenite treatment. Selenomethionine (SeMet) was the main organic species (67-86%) in wheat grains, followed by selenocysteine (SeCys₂). In summary, our results indicate that Se biofortification of wheat is most effective with 20 g ha^-1 selenate foliar-applied at pre-filling stage.

Methods of Selenium Application Differentially Modulate Plant Growth, Selenium Accumulation and Speciation, Protein, Anthocyanins and Concentrations of Mineral Elements in Purple-Grained Wheat

Selenium (Se) is an essential micronutrient for human health. Deficiency and suboptimality of Se in human populations are a potential health risk. The reduction of such health risk by biofortification of crops, particularly in wheat has drawn much attention, especially for color-grained wheat as it is rich in anthocyanins and can be used as a major source of antioxidants in diet. Herein, a two-year field study on the purple-grained wheat cultivar (202w17) and common wheat cultivar (Shannong 129) was conducted with soil application (SeS) and foliar spray (SeF) of selenium. Results showed that the SeS increased shoot dry weight and grain yield. Both SeS and SeF enhanced the concentration of organic Se, but the higher concentration of organic Se in the grain of two cultivars was observed in SeF in comparison with SeS. The concentration of organic Se in the grain of 202w17 treated with SeF was approximately 1.5-fold of that in Shannong 129 with SeF. The analysis of Se accumulation in different parts of the plant revealed that 202w17 accumulated more Se in shoots and grain than Shannong 129, and 202w17 had also higher levels of total protein, total free amino acids and anthocyanin in grain than Shannong 129. In addition, SeF significantly increased the concentrations of zinc (Zn), calcium (Ca), magnesium (Mg) in both cultivars, but decreased the concentration of chromium (Cr), cadmium (Cd) and lead (Pd), which phenomenon was more significant in 202w17. Our results indicate that SeS increases plant growth, leading to higher grain yield in two cultivars tested. The purple-grained wheat (202w17) could accumulate more Se in grain and have a higher concentration of orgainic Se in grain than the common wheat (Shannong 129).

Development of Pasta Products with Nonconventional Ingredients and Their Effect on Selected Quality Characteristics: A Brief Overview

Pasta is a widely consumed food in all over the world. Coarse semolina obtained from durum wheat and water are the main ingredients of conventional pasta products. The amount of gluten and quality level of durum wheat, are two important factors for the superiority of finished pasta. Market price of durum wheat is higher than the common wheat and it contributes no more than 5% of the world wheat production. Thus, to come across the challenge of emerging pasta consumption, new field of research that is dealing with the incorporation of nonconventional ingredients to the conventional formula of pasta has initiated. The compositions of raw materials which are used for pasta preparation directly affect the physical, chemical, and textural properties of the product. Therefore, incorporation of nonconventional ingredients can lead to a contradictory effect of pasta quality. This review will focus on the various types of nonconventional ingredients that are being incorporated in pasta products and their effect on the quality attributes of different pasta products.

Accumulation, mobilization, and transformation of selenium in rice grain provided with foliar sodium selenite

BACKGROUND

Selenium is an indispensable trace element for humans and its deficiency can lead to serious health complications. Nearly 70% of the area of China faces selenium deficiency. To deal with this problem, selenium-enriched rice has been increasingly incorporated into everyday diets. However, there is a lack of in-depth studies of the absorption, translocation, and transformation of selenium in the different parts of the rice plant when sprayed with sodium selenite.

RESULTS

Foliar sodium selenite applied at critical growth stages can significantly improve the total and organic selenium content of plants. Application of 10 mg L^-1 sodium selenite led to the most organic selenium (0.03 mg kg^-1 ) in polished rice. Correlation studies of sodium selenite applied to leaves and other plant parts showed that total selenium accumulated most in glume, followed by rice bran, then polished rice, and finally embryo. The behavior of organic selenium was different. Organic selenium accumulated most in polished rice, then embryo, then rice bran, and finally glume. Moreover, 75-85% of the Se found in polished rice and embryo was organic in nature.

CONCLUSIONS

We propose that 10 mg L^-1 sodium selenite can be recommended as appropriate for foliar fertilization in the organic selenium biofortification of Se-free rice. © 2018 Society of Chemical Industry.

Selenoproteins in human body: focus on thyroid pathophysiology

Selenium (Se) has a multilevel, complex and dynamic effect on the human body as a major component of selenocysteine, incorporated into selenoproteins, which include the selenocysteine-containing enzymes iodothyronine deiodinases. At the thyroid level, these proteins play an essential role in antioxidant protection and hormone metabolism. This is a narrative review based on PubMed/Medline database research regarding thyroid physiology and conditions with Se and Se-protein interferences. In humans, Se-dependent enzyme functions are best expressed through optimal Se intake, although there is gap in our knowledge concerning the precise mechanisms underlying the interrelation. There is a good level of evidence linking low serum Se to autoimmune thyroid diseases and, to a lesser extent, differentiated thyroid cancer. However, when it comes to routine supplementation, the results are heterogeneous, except in the case of mild Graves' orbitopathy. Autoimmune hypothyroidism is associated with a state of higher oxidative stress, but not all studies found an improvement of thyroid function after Se was introduced as antioxidant support. Meanwhile, no routine supplementation is recommended. Low Se intake is correlated with an increased risk of developing antithyroid antibodies, its supplementation decreasing their titres; there is also a potential reduction in levothyroxine replacement dose required for hypothyroidism and/or the possibility that it prevents progression of subclinical hypothyroidism, although not all studies agree. In thyroid-associated orbitopathy, euthyroidism is more rapidly achieved if the micronutrient is added to traditional drugs, while controls appear to benefit from the microelement only if they are deficient; thus, a basal assay of Se appears advisable to better select patients who need substitution. Clearly, further Se status biomarkers are required. Future introduction of individual supplementation algorithms based on baseline micronutrient levels, underlying or at-risk clinical conditions, and perhaps selenoprotein gene polymorphisms is envisaged.