These are screening calculations, not evidence that consumption causes illness, and they depend on treating total mercury as a methylmercury surrogate and assuming that inorganic arsenic accounts for 10% of total arsenic. The researchers sampled muscle and liver from 86 dolphinfish, Coryphaena hippurus, and 65 striped marlin, Kajikia audax, collected during sport-fishing trips off Cabo San Lucas, Mexico, in 2018 and 2019. The sample comprised 40 male and 46 female dolphinfish, with a mean fork length of 81.2 ± 14.7 centimeters and mean weight of 4.7 ± 2.8 kilograms.

It included 32 male and 33 female striped marlin, whose mean lower-jaw fork length was 183.4 ± 19.4 centimeters and mean weight 31.9 ± 10.7 kilograms. Fish were selected because striped marlin commonly occur in the area and the Gulf of California receives contaminants from mining, intensive agriculture, shrimp aquaculture, fisheries and urban activity, according to the study. Tissue preparation and elemental analysis were designed to measure mercury, arsenic and selenium in both species and both tissues.

Muscle and liver samples were frozen at −19°C, freeze-dried at −48°C and 133 × 10−3 mbar for 48 hours, and ground with an agate mortar. Portions weighing 0.25 grams underwent overnight acid addition and three-hour digestion in capped vessels at 120°C. Total mercury was measured by cold-vapor atomic absorption spectrophotometry, total arsenic by hydride-generation atomic absorption spectrophotometry and selenium by graphite-furnace atomic absorption spectrophotometry. Duplicate samples, high-purity reagents, ultrapure water and certified reference materials were used for quality control, with reference-material recoveries of 94–96% for mercury, 92–95% for selenium and 98–102% for arsenic.

All reported concentrations were converted from dry weight to micrograms per gram of wet weight. Median concentrations in dolphinfish muscle were 0.08 micrograms per gram wet weight for mercury, 0.81 for arsenic and 0.20 for selenium. Its liver medians were 0.09 micrograms per gram for mercury, 2.40 for arsenic and 0.27 for selenium.

In striped marlin muscle, the corresponding medians were 0.29 micrograms per gram for mercury, 0.591 for arsenic and 0.27 for selenium; liver medians were 0.12 for mercury, 1.50 for arsenic and 0.23 micrograms per gram for selenium. Arsenic had the highest median concentration in every species-and-tissue combination, but the modeled risk rankings differed because the assessment incorporated element-specific oral reference doses and the assumed inorganic fraction of total arsenic. Element concentrations generally increased with fish size in significant associations identified by Spearman rank correlation and Bonferroni correction.

Mercury in both muscle and liver was positively associated with length and weight in both species, with correlation coefficients of 0.408–0.461 in dolphinfish and 0.463–0.551 in striped marlin. Dolphinfish length and weight were also positively associated with arsenic in muscle and liver, with coefficients of 0.429–0.461. In striped marlin, weight was positively associated with arsenic and selenium in muscle, at 0.497 and 0.435, respectively, but no significant relationships linked those elements to body size in liver.

Selenium in dolphinfish muscle was not significantly associated with size. The researchers did not directly measure fish age, so the observed size relationships do not by themselves establish that larger fish had experienced longer exposure. Comparisons between the 2018 and 2019 sampling periods found no statistically significant differences in elemental concentrations within the compared tissues of either species.

The researchers therefore pooled the two years for the dietary assessment. That finding covers only the sampled years and does not establish that contaminant levels remained stable over longer periods. The catch also had a size profile that may limit generalization: sampled dolphinfish were adults, apparently reflecting the tendency of sport-fishing tournaments to target larger fish, whereas most sampled striped marlin were below reported lower-jaw fork lengths at first maturity.

For the dietary calculations, researchers used estimated per-capita consumption rates in northwestern Mexico of 4.1 grams per day for dolphinfish and 21.9 grams per day for striped marlin. Exposure was estimated for three consumer groups: children weighing 30 kilograms, women of childbearing age weighing 65 kilograms and men weighing 75 kilograms. The assessment used oral reference doses of 0.0003 milligrams per kilogram of body weight per day for arsenic, 0.0001 for mercury expressed as methylmercury and 0.0005 for selenium.

For every species and consumer group, the hazard quotient for mercury was greater than that for selenium, which in turn was greater than the arsenic hazard quotient. Mercury accounted for more than 93% of the combined hazard index for dolphinfish: 93.2% for children, 93.26% for women of childbearing age and 93.43% for men. In striped marlin, its contribution was approximately 97.6% in each group, reaching 97.57% for children and women of childbearing age and 97.56% for men.

The different hazard-index results for the two species therefore emerged from the combined influence of measured concentrations, species-specific consumption rates and consumer body weights, rather than from a simple comparison of total mercury concentrations. All hazard-index values associated with dolphinfish were below 1. For striped marlin, 53 of 64 samples exceeded 1 in the children’s scenario, 29 of 64 did so for women of childbearing age and 21 of 64 for men.

The study describes these proportions as estimates for the specified groups and consumption assumptions, not observed clinical outcomes. The hazard index is a screening approach and does not establish that harm will occur. The analysis also did not characterize exposure from every fish species in a consumer’s diet, and its population-wide consumption rates may not capture differences associated with socioeconomic status.

Although fishing-dependent households may consume fish at higher rates, the study did not directly quantify those variations. The absence of direct chemical speciation also limited the assessment: methylmercury was not measured separately, and inorganic arsenic was represented by an assumed share of total arsenic rather than direct measurement. The researchers also calculated a selenium health-benefit value, or HBVSe, using the molar concentrations of selenium and mercury.

All values were positive in muscle and liver from both species, indicating a molar excess of selenium over mercury. Mean HBVSe values were 2.51 in dolphinfish muscle and 2.99 in striped marlin muscle; values were higher in liver. The authors interpreted the pattern as indicating potential selenium–mercury antagonism, in which selenium may mitigate effects associated with mercury.

This toxicological model does not directly show that selenium cancels dietary mercury risk in people, and the positive values coexist with the screening estimates in which mercury remains the principal source of potential risk. By measuring mercury, arsenic and selenium simultaneously in the muscle and liver of both species, the study expands a regional evidence base in which monitoring has been uneven and arsenic data are particularly limited. The results show that the highest measured median concentrations were for arsenic, while the modeled risk estimates were driven chiefly by mercury.

For people who consume fish frequently, the study supports continued monitoring and dietary risk assessment, particularly for children and women of childbearing age, as well as broader consideration of consumers with elevated fish-consumption rates. It does not establish that the sampled fish are broadly unsafe to eat, identify an actual clinical effect or resolve the uncertainties created by assumed chemical speciation, limited dietary data and a sport-fishing sample. Direct measurement of mercury and arsenic species, more representative sampling and more detailed information about individual consumption would be needed for a more precise assessment of exposure.

Subject of Research: Dietary mercury, arsenic and selenium risk assessment in Gulf of California dolphinfish and striped marlin

Article Title: Health risk assessment associated with Hg, As, and Se in the dolphinfish Coryphaena hippurus and the striped marlin Kajikia audax from the southern Gulf of California

Article References: Ruelas-Inzunza, J., Arriaga-Flores, Y. K., Sánchez-Osuna, K. G., Gil-Manrique, B., Escobar-Sánchez, O., Spanopoulos-Zarco, P., & Vega-Sánchez, B. (2026). Health risk assessment associated with Hg, As, and Se in the dolphinfish Coryphaena hippurus and the striped marlin Kajikia audax from the southern Gulf of California. Frontiers in Marine Science, 13, Article 1950335. https://doi.org/10.3389/fmars.2026.1950335

Image Credits: AI Generated

DOI: 10.3389/fmars.2026.1950335

Keywords: dolphinfish, striped marlin, mercury, arsenic, selenium, dietary risk assessment, hazard index, Gulf of California, marine fish, food contaminants, Health, risk

The coefficient was calculated through a three-step process. First, relative abundance numbers for selenium and eight other metals were derived from their abundance in igneous rock, soil, fresh water, terrestrial plants and terrestrial animals. For each medium, the most abundant element was assigned 1 and the others proportional values. The highest value for each element was then excluded, and the remaining four values were summed to limit the influence of an extreme value.

Second, the average abundance number for each element was multiplied by a sink factor reflecting its relative sedimentation tendency. These calculations produced initial toxicity coefficients spanning from 57 to 353,728. Third, the researchers standardized the values relative to zinc, the element with the lowest initial coefficient, and took the square root of each ratio. This step produced a selenium coefficient of 1.9, which was rounded to 2. Comparison with published coefficients for the other eight elements showed small numerical differences but generally consistent relative ordering and multiplicative relationships.

For the national application, researchers systematically collected studies of soil selenium concentrations in China published from 1980 through 2024. Eligible studies sampled the surface layer at depths of 0 to 20 centimetres, used precise instrumental methods such as atomic fluorescence spectrometry or inductively coupled plasma mass spectrometry, and reported means and standard deviations. The compilation contained measurements from 1,232 sampling sites. Although digestion protocols differed among the included studies, the authors considered this heterogeneity inherent to the meta-analysis and stated that it did not compromise their primary objective of calculating the coefficient.

The assessment used 0.21 milligrams per kilogram as the national geochemical background concentration for selenium in Chinese surface soils. The single-element potential ecological risk factor incorporated measured concentration, background concentration and the toxicity coefficient. Risk categories were defined as low below 2, moderate from 2 to below 4, considerable from 4 to below 8, high from 8 to below 16 and very high at 16 or above. A separate geoaccumulation index, also based on the 0.21 milligrams-per-kilogram background, was used with a correction factor of 1.5 to compare contamination classes.

The compiled selenium concentrations ranged from 0.007 to 25.42 milligrams per kilogram, with a mean of approximately 0.35 milligrams per kilogram. Kriging interpolation showed generally higher concentrations in southeastern China and lower concentrations in northwestern China, although the map was used to visualize broad spatial patterns rather than calculate an area-weighted national estimate. Under the GB/T 44971–2024 soil selenium grading standard cited by the researchers, about 36.4% of the sampling sites were classified as selenium-rich or higher, while approximately 2.67% exceeded the 3 milligrams-per-kilogram toxicity threshold.

Elevated risk occurred mainly in Enshi in Hubei Province, Ziyang in Shaanxi Province, Kaiyang in Guizhou Province and Chao’an in Guangdong Province. The researchers associated these localized anomalies with selenium-enriched geological strata or hydrothermal influence. One Chao’an site had a potential ecological risk factor of 140.71, placing it in the very-high-risk category. They cautioned that this value describes potential risk from total soil selenium and does not demonstrate actual biological toxic effects; the study cited limited selenium uptake by tea plants and no reported selenosis incidents at that location.

The potential ecological risk factor and geoaccumulation index showed a quadratic weighted Kappa coefficient of 0.729, indicating substantial agreement between their ordered classifications. An exponential regression was also significant at p less than 0.001, but the authors cautioned that this correlation partly arose because both indices use measured soil selenium concentration and therefore did not independently validate the coefficient. They further noted that, for a single-element risk classification, the selenium coefficient mathematically cancels out and does not change the category assigned to an individual site.

Accordingly, the scientific value of the coefficient of 2 lies in providing selenium’s relative toxicity weight for multi-element calculations and establishing a consistent parameter for screening comparisons. The study was a literature-based ecological risk assessment rather than a direct measurement of selenium toxicity, plant uptake or organism-level effects. It did not account for selenium speciation, pH, redox conditions, organic matter or bioavailability, and all percentages refer to the 1,232 sampling sites rather than China’s total land area. The authors describe the result as a preliminary screening benchmark for prioritizing site-specific investigation, not as a definitive basis for land management or environmental standard revision.

Subject of Research: National screening assessment of potential ecological risk from selenium in Chinese surface soils

Article Title: Calculation and application of the selenium toxicity coefficient for potential ecological risk assessment

Article References: Wen, X., & Huang, Y. (2026). Calculation and application of the selenium toxicity coefficient for potential ecological risk assessment. PLOS One, 21(10), e0359642. https://doi.org/10.1371/journal.pone.0359642

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0359642

Keywords: selenium, soil contamination, ecological risk, toxicity coefficient, Håkanson risk index, geoaccumulation index, China, environmental screening, Calculation, application, toxicity, coefficient

The choice of wheat as the experimental subject reflects both its global importance and its well-documented sensitivity to salinity during early development. Wheat is among the most widely cultivated cereals on Earth, and in many irrigated production systems—particularly in arid and semi-arid regions of Central and Western Asia, North Africa, and Australia—the water available to farmers carries substantial dissolved salt loads. Seedling establishment is a particularly vulnerable window, because young plants have limited root systems, thin cuticles, and immature antioxidant machinery. A seedling that survives early salt exposure with reduced vigor often carries that penalty through to tillering and grain fill, which is why interventions aimed specifically at the seedling stage can have disproportionate agronomic value even when the plants eventually recover.

The two cultivars examined in the study, Chamran and Mehregan, are bread wheat varieties bred for the contrasting but overlapping challenges of Iranian and regional production environments. Including two genotypes rather than one matters scientifically because salt responses in wheat are strongly genotype-dependent: varieties differ in their capacity to exclude sodium at the root, to compartmentalize it in vacuoles, and to maintain photosynthetic activity under osmotic strain. When a treatment effect appears in both cultivars, as the fresh-weight benefit of the combined formulation did at every salinity level tested, it suggests a mechanism that operates broadly rather than one contingent on a particular genetic background. At the same time, the magnitude of the benefit differed between the two lines, with Mehregan showing a larger relative gain at the highest salt concentration, a reminder that biostimulant performance cannot be assumed to transfer uniformly across germplasm.

The severity of the salt treatments deserves attention when interpreting the results. Irrigating with 150 millimolar sodium chloride already imposes stress well beyond what most productive wheat fields experience; 300 millimolar approaches the limits of what wheat seedlings can tolerate at all. These concentrations were chosen to create a steep stress gradient in which protective effects could be detected unambiguously, not to mimic field conditions directly. The fact that plant height, fresh weight, and dry weight all declined substantially at the highest concentration in both cultivars confirms that the stress was genuinely severe. Against that backdrop, even modest absolute differences in biomass between sprayed and unsprayed plants represent meaningful biological protection, and the roughly thirty-five percent fresh-weight advantage of the combined treatment over the unsprayed control in Chamran at 300 millimolar sodium chloride is notable.

Chitosan itself has a long history as a plant-protective agent, and its mechanism of action is worth unpacking. Derived by deacetylation of chitin from crustacean shells or fungal cell walls, chitosan is a positively charged polysaccharide that can interact with negatively charged components of plant cell surfaces. It is recognized by plants as a microbe-associated molecular pattern, triggering innate immune signaling pathways that overlap with those activated during abiotic stress. Spraying chitosan on leaves has been reported to induce stomatal closure, stimulate the phenylpropanoid pathway, and prime antioxidant enzymes, effects that collectively harden plants against subsequent stress. The polymer also forms films, which is why it is used commercially as an edible coating for fruit; on a leaf, that film-forming behavior may both retain moisture and slow the diffusion of dissolved solutes.

Selenium occupies an unusual position in plant biology. It is not considered an essential element for higher plants, yet at low concentrations it reliably alleviates oxidative stress in many species. The reason lies in its chemistry: selenite taken up by leaf tissue can be assimilated into selenocysteine and ultimately into selenium-containing forms that bolster the glutathione peroxidase system, an alternative route for decomposing lipid peroxides that complements the ascorbate-glutathione cycle. Selenium supplementation has also been shown to enhance the activity of catalase and superoxide dismutase and to slow chlorophyll degradation under stress. The dose window is narrow, however, because selenium becomes toxic to plants at concentrations only modestly above those that are beneficial, which makes delivery method and formulation critical variables in any field application.

The formulation strategy used in the study—ionotropic gelation with tripolyphosphate—is a standard technique for assembling chitosan into small cross-linked particles. When a tripolyphosphate solution is added to an acidic chitosan solution, the multivalent anion bridges the cationic polymer chains, condensing them into discrete nanoparticles. Incorporating sodium selenite into this process entraps or associates the selenium species within the particle matrix rather than leaving it as a free salt on the leaf surface. The practical rationale is that a particle-associated active ingredient may adhere better to the waxy cuticle, release its payload more gradually, and suffer less from rapid wash-off or photodegradation than a simple aqueous spray. The authors were careful, however, to note that the physicochemical properties of their specific formulation—particle size, surface charge, selenium loading efficiency, and release kinetics—were not characterized in this work, leaving an important gap between the concept and a fully validated delivery system.

The confocal microscopy experiment using fluorescein isothiocyanate-labeled chitosan provides some of the most visually direct evidence in the paper. Fluorescence was strongest in the epidermal layer and weaker in the underlying mesophyll, indicating that the polymer associates readily with the outer leaf tissues but penetrates only partially into the interior. This pattern is consistent with what is known about foliar uptake in general: the cuticle is a formidable hydrophobic barrier, and most solutes enter through stomata, trichomes, or specialized epidermal cells rather than diffusing across the cutin matrix. The authors are appropriately cautious in their interpretation, emphasizing that detecting the labeled chitosan demonstrates association with the leaf but does not prove that selenium, or the intact formulation, was internalized. Tracking the selenium itself would require a different analytical approach, such as isotope labeling or elemental imaging.

The gene expression data add a molecular dimension to the physiological observations. The genes examined span several functional categories that map directly onto the known components of salt stress. TaAPX and TaCAT encode ascorbate peroxidase and catalase, the two central enzymes of hydrogen peroxide detoxification. TaNHX1 encodes a vacuolar sodium-proton antiporter that sequesters sodium ions inside vacuoles, removing them from the cytoplasm where they would interfere with enzymatic function. TaHKT9-7D belongs to the high-affinity potassium transporter family, whose members participate in sodium retrieval and potassium-sodium balance in both roots and leaves. TaP5CS catalyzes the rate-limiting step in proline biosynthesis, and Ta4CL3-6B encodes a 4-coumarate ligase acting early in the phenylpropanoid pathway, which supplies lignin precursors and a wide range of protective secondary metabolites. TaPXPAO is involved in polyamine catabolism, a process that both generates hydrogen peroxide and participates in stress signaling.

The pattern of expression changes tells a coherent story. In unsprayed plants, salt exposure actually decreased the transcript levels of most of these genes, a somewhat counterintuitive result that may reflect stress-imposed suppression of transcription or a failure of the seedlings to mount a full defensive response at the severe concentrations used. The single gene that rose, TaP5CS, aligns with the accumulation of proline, the classic osmoprotectant whose synthesis plants upregulate under water stress. In contrast, the selenium-containing treatments at the highest salt level elevated TaCAT, TaNHX1, and Ta4CL3-6B in both cultivars, suggesting activation of antioxidant defense, sodium compartmentalization, and phenylpropanoid metabolism respectively. The combined formulation additionally influenced the polyamine catabolism gene, hinting at a broader reprogramming of stress metabolism when the two biostimulants act together.

The authors are explicit that these expression changes are correlative: no enzyme activities, metabolite quantities, or ion contents were measured to confirm that the transcriptional shifts translated into functional differences. This is a standard and honest limitation of RT-qPCR surveys, and it defines the agenda for follow-up work. Measuring catalase activity, tissue sodium and potassium concentrations, proline levels alongside TaP5CS expression, and phenylpropanoid end products would connect the molecular signals to the growth outcomes. Similarly, the weak correlation between growth traits and pigment contents, with correlation coefficients not exceeding 0.30, indicates that the fresh-weight benefit of the treatment cannot be explained simply by preserved chlorophyll; other processes, such as osmotic adjustment, membrane stability, or ion homeostasis, are likely contributing.

The proline data illustrate this point nicely. Proline rose with increasing salinity in the selenium-treated and combined-treatment plants, consistent with induced TaP5CS expression, and proline serves multiple roles beyond osmotic adjustment: it scavenges reactive oxygen species directly, stabilizes proteins and membranes, and buffers cellular redox state. A treatment that enhances proline accumulation under salt stress therefore plausibly contributes to the observed biomass protection through mechanisms invisible to chlorophyll measurements. Disentangling how much of the growth benefit flows through osmotic protection versus antioxidant reinforcement versus ion management will require the kind of integrative physiological follow-up the authors themselves call for.

From an applied perspective, the study sits within a growing literature on biostimulants as complements to conventional breeding and soil management for salinity adaptation. Breeding for salt tolerance in wheat has proven slow because tolerance is controlled by many genes of modest effect and is strongly environment-dependent. Foliar interventions offer a complementary route: they can be applied reactively when salinity is known to be a problem, combined with existing agronomic practice, and adjusted by dose and timing. The caveats the authors raise—uncharacterized formulation physics, seedling-stage results only, controlled-environment conditions, and no field validation—are the standard hurdles between a promising greenhouse result and a usable product, and their candor about them strengthens rather than weakens the study’s contribution. The work was supported by Hungarian national research funding through the Thematic Excellence Program and the NRDI Fund, and the article is published open access under a Creative Commons license, making the full dataset and methods available to any research group wishing to build on these findings.

Subject of Research: Foliar chitosan–selenite biostimulant effects on wheat seedlings under salt stress

Article Title: Foliar chitosan–selenite formulation improves wheat seedling growth under NaCl irrigation

Article References: Gholizadeh, F., Fábián, A., Sohail, H., Majláth, I., & Janda, T. (2026). Foliar chitosan–selenite formulation improves wheat seedling growth under NaCl irrigation. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10095-7

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10095-7

Keywords: wheat, salinity stress, chitosan, selenium, foliar application, biostimulants, gene expression, antioxidant defense, proline, confocal microscopy, plant physiology, NaCl

The choice of plant material was not arbitrary. Radish leaves (Raphanus sativus var. longipinnatus) are rich in glucosinolates and phenolic compounds with documented antioxidant and antibacterial effects, and these phytochemicals act as natural reducing and stabilizing agents during nanoparticle formation. Lemon peel (Citrus limon) contributes flavonoids, phenols, and essential oils that serve the same dual function for selenium, a semiconductor known for its antibacterial, anticancer, and antioxidant properties but notorious for colloidal instability when synthesized by conventional means. By using these extracts, the team produced stable selenium nanoparticles without any synthetic additives.

The synthesis process itself was carefully controlled. Radish leaves were dried at 60 degrees Celsius, ground into a fine powder, and extracted in deionized water at 80 degrees Celsius for 15 minutes before centrifugation to remove colloidal debris. Zinc acetate was then dissolved and combined with the radish leaf extract in ethanol, with sodium hydroxide adjusting the pH to 12 before heating at 70 degrees Celsius. The resulting white precipitate was washed, dried, and calcined at 450 degrees Celsius for two hours to crystallize the zinc oxide and eliminate residual organic material. Selenium nanoparticles were prepared separately by combining an 8 millimolar sodium selenite solution with lemon peel powder, incubating first at 70 degrees Celsius to trigger rapid nucleation and then at 37 degrees Celsius for 72 hours to allow controlled crystal growth, with the solution turning from light yellow to brick red as the nanoparticles formed.

X-ray diffraction confirmed that the zinc oxide adopted the hexagonal wurtzite structure, with characteristic peaks matching the standard reference pattern and no secondary phases detected. Using the Scherrer equation, the average crystallite size of pure zinc oxide was determined to be 14.15 nanometers. Selenium nanoparticles showed sharp peaks corresponding to the hexagonal elemental selenium structure, with an average crystallite size of 19.1 nanometers. When the two were combined into nanocomposites at 2, 6, and 10 weight percent selenium, the wurtzite peaks remained unchanged in position, indicating that selenium did not substitute into the zinc oxide lattice but instead formed a separate phase in intimate contact with the host matrix.

Perhaps the most striking structural finding was that the 2 weight percent selenium composite produced the smallest crystallites of any sample, at 12.51 nanometers, compared to 14.15 nanometers for pure zinc oxide and 15.22 nanometers at 10 weight percent selenium. The researchers attribute this to a Zener pinning effect, in which selenium domains dispersed at grain boundaries physically restrict crystal growth during thermal treatment. As selenium concentration increased beyond the optimum, lattice strain decreased systematically from 7.84 × 10⁻³ to 5.41 × 10⁻³, suggesting internal stress relaxation rather than major lattice distortion.

Ultraviolet-visible spectroscopy reinforced the two-phase picture. Pure zinc oxide showed a sharp absorption peak at approximately 370 nanometers, consistent with its wide bandgap of roughly 3.37 electronvolts. Selenium nanoparticles exhibited a primary peak at 275 nanometers, a significant blue shift from bulk selenium that confirms quantum confinement effects in particles smaller than the Bohr exciton radius. Tauc analysis of the composites revealed that the 2 weight percent sample displayed the highest absorption intensity at 370 nanometers, while higher selenium loadings showed progressively lower absorption, likely due to surface coverage and aggregation effects that reduce the effective optical path.

Field emission scanning electron microscopy revealed that pure zinc oxide forms dense aggregates of 4 to 6 primary crystals, with secondary particle diameters averaging 68.4 nanometers. Pure selenium nanoparticles adopted elongated one-dimensional structures with aspect ratios between 5.2 and 8.7, attributed to the pectin and flavonoid matrix of the lemon peel extract directing asymmetric growth. However, when incorporated into the zinc oxide matrix, these one-dimensional selenium structures were mechanically fragmented during magnetic stirring, resulting in more isotropic domains. Energy dispersive X-ray analysis and elemental mapping confirmed that selenium was uniformly distributed throughout the composite without agglomeration, even at the highest loading of 10 weight percent.

The photocatalytic performance was evaluated by degrading methyl orange, a common azo dye pollutant, under ultraviolet-A irradiation at 365 nanometers. Pure zinc oxide achieved 62.4 percent degradation in 120 minutes, but the 2 weight percent selenium composite reached 83.4 ± 0.7 percent under identical conditions, a statistically significant improvement validated across three independent biological replicates. The pseudo-first-order rate constant for the optimal composite was 0.0150 per minute with a half-life of 46.20 minutes, compared to 0.0081 per minute and 85.56 minutes for pristine zinc oxide. The enhancement is attributed to strengthened interfacial contact between the two phases, which promotes efficient charge separation and reduces electron-hole recombination, extending the lifetime of reactive oxygen species responsible for breaking down the dye molecules.

Antimicrobial testing against Staphylococcus aureus, Klebsiella pneumoniae, and Candida albicans revealed a nuanced picture. The 2 weight percent composite produced the largest inhibition zones, measuring 19.0 ± 0.5 millimeters against Staphylococcus aureus and 17.0 ± 0.4 millimeters against Klebsiella pneumoniae. All formulations showed strong activity against Candida albicans with minimum inhibitory concentrations at or below 32 micrograms per milliliter, likely driven by zinc ion release and reactive oxygen species generation that compromise the fungal cell wall. However, antibacterial efficacy against the bacterial strains declined as selenium concentration increased beyond 2 weight percent, a phenomenon the researchers link to a shadowing effect in which excess selenium covers active zinc oxide surface sites, combined with colloidal aggregation and competitive surface binding that reduce the effective surface area available for ion release and membrane disruption.

The authors describe the optimal 2 weight percent formulation as a

Subject of Research: Green synthesis of ZnO/Se nanocomposites: influence of selenium concentration on structural, optical properties with enhanced antimicrobial and photocatalytic performance

Article Title: Green synthesis of ZnO/Se nanocomposites: influence of selenium concentration on structural, optical properties with enhanced antimicrobial and photocatalytic performance

Article References: Al-Kilabi, R., Al-Hello, H., Mohammed, E. F., Al-Hello, M., Hassoon, O. A., Yaseen, M. A., & Al-Saidi, M. H. (2026). Green synthesis of ZnO/Se nanocomposites: influence of selenium concentration on structural, optical properties with enhanced antimicrobial and photocatalytic performance. Frontiers in Ecology and Evolution, 14, Article 1939540. https://doi.org/10.3389/fevo.2026.1939540

Image Credits: AI Generated

DOI: 10.3389/fevo.2026.1939540

Keywords: Green, synthesis, nanocomposites, influence, selenium, concentration, structural, optical, properties, enhanced, antimicrobial, photocatalytic

The premise is deceptively simple. Goats are evolutionary intermediates between browsers and grazers, and studies show they can satisfy up to 60 percent of their nutritional needs from foliage when given the choice. Yet European husbandry guidelines recommend pasture access without requiring access to trees and shrubs. Fast-growing poplars and willows, cultivated widely in alley-cropping and short-rotation plantations across temperate latitudes, already serve as feed for sheep and cattle in New Zealand, China, North America, and parts of Europe. In Germany alone, roughly 6,600 hectares of short-rotation poplar and willow plantations yield about nine tonnes of woody dry mass per hectare annually, along with up to three tonnes of foliage per hectare in the second year after planting. Whether that foliage actually delivers usable nutrition to goats, however, had never been thoroughly tested.

The researchers ran two linked experiments. In the first, four castrated Saanen goat wethers, each about 1.5 years old, were rotated through four diets in a 4-by-4 Latin square design: meadow hay alone, or hay supplemented with 650 grams per day of dried foliage from one of three hybrids, black poplar (Populus nigra × deltoides), balsam poplar (P. nigra × maximowiczii), or willow (Salix triandra × viminalis). During the third week of each feeding block, the animals were moved into respiration chambers where oxygen consumption, carbon dioxide production, and methane emissions were measured at six-minute intervals, while feces and urine were collected for complete nutrient, energy, and mineral balance calculations.

The chemical analysis alone was enough to turn heads. Compared with hay, the tree leaves contained up to ten times higher concentrations of crude protein, minerals, phenols, and measurable antioxidant capacity. Black poplar leaves were particularly rich in calcium at 21.6 grams per kilogram of dry matter, roughly five times the hay content, along with markedly higher zinc, copper, iron, magnesium, and selenium. Willow leaves carried the highest manganese levels and, remarkably, showed antioxidant capacity six to ten times greater than hay in standard ABTS and FRAP assays. The foliage also packed condensed tannins and phenolic compounds at two to three times the hay concentrations, a double-edged property that would prove consequential later in the study.

Digestibility results favored the poplars. Balsam poplar diets achieved the highest organic matter digestibility at 64 percent, compared with 59 percent for hay and just 56.1 percent for willow. Willow fared worst across the board, posting the lowest crude protein digestibility at 52.9 percent and the lowest fiber digestibility, a deficit the researchers attribute to its extraordinary condensed tannin content of 116.6 grams per kilogram of dry matter, some 22-fold higher than the poplar leaves. Tannins bind proteins and nutrients in the rumen, forming complexes that resist digestion and inflate fecal nitrogen losses. Despite this, microbial protein production in the rumen, estimated from urinary purine derivatives, was unaffected by any of the foliage diets.

Perhaps the most climate-relevant finding was what came out of the animals as gas. Methane emitted per kilogram of dry matter intake was significantly lower on all three foliage diets than on hay, with willow delivering the largest reduction at 17.2 grams per kilogram versus 22.4 for hay. Tannins suppress methanogenic archaea in the rumen, and the bacteriostatic effect appears to translate directly into reduced enteric methane, the potent greenhouse gas that accounts for a substantial share of livestock agriculture’s climate footprint. Notably, foliage feeding raised no red flags for food safety: despite leaves accumulating more zinc, manganese, nickel, and lead than hay, plasma concentrations of these heavy metals in the goats remained indistinguishable from hay-fed controls.

Selenium told a subtler story. Although balsam poplar leaves contained the most selenium, wethers fed the black poplar diet showed the highest plasma selenium at 72.6 micrograms per liter, significantly above both the balsam poplar and hay groups. Because selenium intake differed only marginally between the two poplar diets, the authors conclude that selenium from black poplar is more bioavailable, possibly reflecting differences between inorganic and organic selenium species in the leaves. This bioavailability advantage carried into the second experiment, where lactating does supplemented with black poplar foliage consumed 2.7 times more selenium and maintained significantly higher plasma selenium concentrations by the fifth week of lactation, hinting that tree foliage could partly substitute inorganic selenium supplements derived from fossil sources.

That second experiment put the most promising candidate to a real-world test. Sixteen pregnant, year-old Saanen goats were split after lambing: half received 700 grams per day of black poplar foliage alongside hay and wheat during the first five weeks of lactation, while the control group received hay and wheat only. The hypothesis was logical, even elegant. The periparturient period imposes crushing energy and calcium demands for fetal growth, colostrum, and milk production, driving negative mineral balances, body fat mobilization, and oxidative stress. Poplar leaves are loaded with calcium, selenium, and polyphenolic antioxidants, precisely the profile that might buffer these stresses.

The results dismantled that hope. Poplar-supplemented does showed no improvement in glutathione peroxidase activity or any other antioxidant marker, despite the leaves’ impressive laboratory antioxidant capacity, suggesting the phenolic compounds were poorly absorbed in vivo. Worse, in the second week after lambing the poplar group exhibited significantly lower serum calcium concentrations and a lower ratio of osteocalcin to CTX, the molecular signatures of bone formation and resorption, indicating intensified bone mobilization. The likely culprit is tannin chemistry: condensed tannins are known to hinder intestinal calcium absorption, and calcium actually enhances the binding between tannins and proteins, compounding the interference. The poplar does were losing more calcium from skeleton despite consuming nearly two and a half times more dietary calcium than controls.

The study’s authors draw a cleanly practical conclusion. Black poplar foliage is a genuinely valuable feed for non-lactating goats, offering improved protein digestibility, selenium status, and reduced methane yield, but it should not be fed to goats in early lactation, when calcium homeostasis is already stretched to its limit. The team acknowledges limitations, including small animal numbers that limited statistical power for mineral balances and methane measurements, and the well-documented sensitivity of leaf composition to harvest time, leaf age, soil, and climate. Still, in an era when agriculture urgently seeks feed resources that cut emissions without competing for cropland, the image of a goat stripping leaves from a poplar row has gained real scientific weight, provided farmers know exactly when in the reproductive calendar to open the gate.

Subject of Research: Nutritional value of poplar and willow foliage in goat diets and its effects on digestibility, selenium status, methane emission, and calcium metabolism around lambing

Article Title: Nutrient and energy digestibility, mineral status and antioxidant defense in goat wethers and periparturient does supplemented with poplar and willow leaves

Article References: Helffenstein, K., Schwerdtfeger, J., Görs, S., Durkalec, M., Kowalczyk, J., Eggert, A., Wilkens, M. R., & Kuhla, B. (2026). Nutrient and energy digestibility, mineral status and antioxidant defense in goat wethers and periparturient does supplemented with poplar and willow leaves. Frontiers in Animal Science, 7, Article 1861647. https://doi.org/10.3389/fanim.2026.1861647

Image Credits: AI Generated

DOI: 10.3389/fanim.2026.1861647

Keywords: goats, poplar foliage, willow, agroforestry, selenium, methane emissions, tannins, calcium metabolism, antioxidants, animal nutrition, early lactation, digestibility

The review, led by Nooneh Khachatourian, Rubina Takhmazian, and Vishwanath Venketaraman, builds on a well-established epidemiological foundation. Undernutrition is already recognized as one of the most significant modifiable risk factors for tuberculosis, with more than one-fifth of global TB cases estimated to be attributable to it. Systematic reviews have shown that undernutrition substantially increases the risk of developing active TB and that malnutrition is associated with worse treatment outcomes, including treatment failure, loss to follow-up, and death. But the relationship runs both ways: TB itself drives nutritional deterioration through chronic inflammation, increased metabolic demands, reduced appetite, and impaired nutrient utilization. What the authors add to this picture is a third player—the thyroid gland—whose hormone output depends critically on the very micronutrients that malnutrition depletes and whose hormones, in turn, help regulate the immune cells that fight M. tuberculosis.

Thyroid hormones, triiodothyronine (T3) and thyroxine (T4), are best known for regulating metabolism, energy expenditure, lipid profiles, glucose utilization, thermogenesis, and body weight. But an accumulating body of experimental evidence shows that they also act directly on the immune system. Macrophages, dendritic cells, neutrophils, and T lymphocytes all express thyroid hormone receptors and respond to thyroid hormone signaling. Experimental studies indicate that these hormones regulate neutrophil respiratory burst activity, reactive oxygen species production, macrophage phagocytic capacity, cytokine signaling, and inflammatory responses. Thyroid hormone receptor α signaling has also been implicated in T-cell activation and in the function of regulatory T cells, which temper pro-inflammatory responses and enhance anti-inflammatory regulation. Because many of these same pathways are central to controlling intracellular pathogens such as M. tuberculosis, the authors propose that hypothyroidism—an extremely common endocrine disorder worldwide—may represent an underrecognized factor compromising antimicrobial defense.

The bridge between nutrition and thyroid function is built from specific micronutrients. Iodine is the structural backbone of both T3 and T4; the body cannot synthesize it, so dietary intake is indispensable. Although iodization programs have reduced severe deficiency, roughly 30 percent of the world’s population remains at risk of inadequate iodine intake, which impairs hormone synthesis and leads to compensatory thyroid enlargement and hypothyroidism. Selenium is equally critical: the thyroid contains the highest concentration of selenium per gram of tissue of any organ in the human body, reflecting the role of selenium-dependent iodothyronine deiodinases (DIO1, DIO2, and DIO3) that convert the prohormone T4 into biologically active T3. Selenium-dependent glutathione peroxidases and thioredoxin reductases also protect thyroid tissue from the oxidative damage generated during hormone biosynthesis, a process that inherently requires hydrogen peroxide as a substrate for thyroid peroxidase-mediated iodination. Selenium deficiency therefore impairs hormone activation, increases oxidative stress, and is associated with autoimmune thyroid disease.

Iron, the most prevalent micronutrient deficiency worldwide, adds another layer. Thyroid peroxidase, the enzyme responsible for iodide oxidation and organification, is heme-dependent and requires adequate iron availability for optimal catalytic activity. A recent systematic review and meta-analysis found significantly lower free T3 and free T4 concentrations among iron-deficient individuals compared with healthy controls. Iron deficiency frequently coexists with chronic inflammation, malnutrition, and infectious disease, which the authors suggest makes its impact on thyroid physiology particularly relevant in populations at elevated TB risk. Zinc contributes through zinc-finger transcription factors and thyroid hormone receptor signaling, with deficiency linked to impaired hormone metabolism and immune dysfunction. Vitamin D, meanwhile, exerts immunomodulatory effects through regulation of T-cell differentiation, cytokine production, and immune tolerance, and observational studies consistently report lower circulating vitamin D concentrations in patients with hypothyroidism, Hashimoto’s thyroiditis, and autoimmune thyroid disease compared with healthy controls.

The immunological case for why thyroid dysfunction might matter in TB rests on the biology of host defense. After inhalation, resident alveolar macrophages constitute the first line of defense, and successful containment of M. tuberculosis requires efficient macrophage activation, granuloma formation, robust T-cell responses, tightly regulated cytokine networks, and control of oxidative stress. Experimental studies show that thyroid hormones regulate macrophage survival and phagocytic activity, influence the production of reactive oxygen species, and modulate the expression of genes involved in antimicrobial responses. On the adaptive side, control of M. tuberculosis depends largely on CD4-positive T lymphocytes generating type 1 helper (Th1) responses characterized by interferon-γ and tumor necrosis factor-α—cytokines that activate infected macrophages and maintain granulomas. Thyroid hormones influence T-cell development, differentiation, and activation through receptor-mediated signaling, so dysregulation of these pathways could plausibly weaken the Th1 response that keeps mycobacteria in check.

Evidence from autoimmune thyroid disease reinforces how closely thyroid function and immune regulation are intertwined. Conditions such as Hashimoto’s thyroiditis and Graves’ disease feature lymphocytic infiltration, loss of immune tolerance, abnormal helper T-cell responses, and chronic cytokine-mediated inflammation, with increased expression of the chemokines CXCL9, CXCL10, and CXCL11 recruiting Th1 lymphocytes into thyroid tissue. Impaired suppressive activity of regulatory T cells has also been reported in autoimmune thyroid disease, and because balanced Treg responses are important for limiting immunopathology during TB infection, such disturbances may further influence susceptibility and disease progression. Beyond direct immune effects, chronic hypothyroidism is associated with low-grade systemic inflammation and altered immune cell metabolism, and thyroid hormones regulate the mitochondrial function, glucose utilization, and lipid metabolism that underpin the energetic demands of immune activation—processes increasingly recognized as determinants of TB outcomes.

The epidemiological spark for this framework comes from an 18-year nationwide population-based longitudinal cohort study, which found that individuals with hypothyroidism had an increased risk of subsequently developing TB, while patients with TB also had an elevated risk of subsequent hypothyroidism. The authors are careful to note that this observational association cannot establish causality and may be confounded by nutritional status, comorbidities, socioeconomic conditions, chronic inflammation, and medication exposure. The relationship is also bidirectional in a treatment context: antitubercular agents including ethionamide, prothionamide, and para-aminosalicylic acid inhibit thyroid peroxidase activity and disrupt iodine organification, producing hypothyroidism in approximately 17 percent of patients receiving treatment for multidrug-resistant TB. Chronic infection itself alters hypothalamic-pituitary-thyroid axis regulation through pro-inflammatory cytokines such as IL-1, IL-6, and TNF-α, meaning TB can both cause and be influenced by endocrine disturbance.

On the intervention side, the review takes a notably sober view of supplementation. Vitamin D is the most extensively studied micronutrient in the TB context because it enhances macrophage antimicrobial activity through induction of cathelicidin, stimulation of autophagy, and promotion of intracellular killing of M. tuberculosis. Yet recent randomized-trial meta-analyses have found no significant reduction in TB infection or progression to active disease with vitamin D supplementation, and limited or inconsistent effects on microbiological treatment outcomes such as sputum smear and culture conversion. The authors argue that evidence supporting correction of a documented deficiency should be distinguished from evidence supporting routine supplementation specifically for TB prevention, and they point to substantial heterogeneity across studies in baseline nutritional status, dose, formulation, duration, and clinical outcomes as a key reason findings have been inconsistent. Similar caution applies to selenium, zinc, and iron: correcting documented deficiencies may support both thyroid and immune function, but evidence that supplementation independently improves TB-specific outcomes remains limited, and excessive intake of certain micronutrients can itself harm endocrine or immune function.

One of the more intriguing therapeutic leads involves glutathione, the body’s principal intracellular antioxidant. Patients with TB frequently exhibit depleted glutathione levels, compromising antioxidant defenses, macrophage function, cytokine regulation, and T-cell-mediated immunity. Experimental and clinical studies suggest that glutathione supplementation may reduce oxidative stress, enhance Th1-associated immune responses, increase production of IFN-γ and TNF-α, and decrease intracellular mycobacterial burden—preliminary but biologically coherent findings, given that glutathione metabolism is closely linked to selenium-dependent antioxidant systems. The authors conclude that the nutritional–endocrine–immune framework they propose is biologically plausible and hypothesis-generating rather than an established causal pathway, and that current evidence does not support routine thyroid screening solely to reduce TB risk. What they call for instead are prospective cohort studies determining whether thyroid dysfunction independently predicts TB after accounting for confounders, adequately powered trials of micronutrient correction in deficient populations, and standardized assessment of nutritional status, thyroid function, and clinical outcomes. If the proposed cycle of malnutrition, thyroid dysfunction, and impaired antimycobacterial immunity holds up under clinical scrutiny, nutritional optimization and early endocrine management could eventually become integrated adjunctive strategies in the fight against one of humanity’s oldest infectious diseases.

Subject of Research: The interplay between nutrition, thyroid function, and immune defense against tuberculosis

Article Title: Nutrition, thyroid function, and tuberculosis: exploring the endocrine–immune axis

Article References: Khachatourian, N., Takhmazian, R., & Venketaraman, V. (2026). Nutrition, thyroid function, and tuberculosis: exploring the endocrine–immune axis. Frontiers in Tuberculosis, 4, Article 1945832. https://doi.org/10.3389/ftubr.2026.1945832

Image Credits: AI Generated

DOI: 10.3389/ftubr.2026.1945832

Keywords: tuberculosis, thyroid hormones, hypothyroidism, micronutrients, iodine, selenium, vitamin D, immune regulation, malnutrition, endocrine-immune axis, glutathione, Mycobacterium tuberculosis

The stakes are larger than they might first appear. Roughly 72 percent of China’s soil area is selenium-deficient, meaning that crops grown across most of the country naturally carry less of the element than human health ideally requires. Selenium enters the food chain through soil, so where the ground is poor, the population’s dietary intake tends to lag as well. This geographic reality has pushed local governments, particularly in regions fortunate enough to sit on selenium-rich land, to develop what are known as selenium-enriched industries: agricultural zones, branding campaigns, and product certification schemes designed to market crops with elevated selenium content as premium health foods.

Under the twin banners of the Healthy China initiative and the Rural Revitalization strategy, selenium-enriched agriculture has become a strategic priority for local administrations seeking to convert a geological accident into economic opportunity. Yet until now, the policy literature surrounding this movement has been surprisingly thin on systematic evaluation. Researchers have extensively explored selenium’s biochemistry and the pathways through which selenium-rich products reach consumers, but almost nobody had rigorously quantified what the policies themselves actually say, how they are constructed, and whether they hang together coherently. The new study set out to close that gap.

The research team assembled a corpus of 42 selenium-enriched policy documents issued in China between 2009 and 2025, a window that captures the full arc of the sector’s emergence from niche experiment to national conversation. Rather than reading these documents impressionistically, the authors subjected them to a three-dimensional analytical framework organized around policy theme, policy instrument, and policy effectiveness. Each dimension was interrogated with a different quantitative tool: Latent Dirichlet Allocation, a machine learning technique that clusters text into latent topics, mapped the thematic landscape; structured content analysis coded the instruments governments deployed; and the Policy Modeling Consistency index, or PMC, scored how internally coherent and operationally robust each policy was.

The first major finding concerns what Chinese policymakers choose to talk about. Across the 16-year corpus, attention concentrates heavily on industrial cultivation and brand building, the activities that translate selenium-rich land into marketable products and regional reputations. By contrast, long-term selenium resource management and cross-regional coordination receive strikingly little attention. This imbalance matters because selenium is a finite geological asset, and uncoordinated exploitation across administrative boundaries risks both depletion and duplication, with neighboring jurisdictions competing for the same niche rather than building complementary supply chains.

The second finding concerns the tools of governance. Policy instruments in the corpus lean predominantly toward supply-side inputs, such as subsidies, infrastructure, and technical support for producers, alongside indirect market cultivation measures that nudge the sector toward maturity without direct intervention. What is largely missing is direct stimulation of consumer health demand, the demand-side lever that would connect selenium-enriched products to the people whose health they are meant to improve. Without consumers actively seeking out these products because they understand and trust the health claims, the entire supply-side apparatus risks building capacity that the market does not absorb.

The third finding is the most encouraging. Using the PMC index model, which scores policy consistency across multiple dimensions including function, instrument, and effectiveness, the researchers found that Chinese selenium-enriched policies demonstrate good operationality, with an average PMC index of 6.9. This suggests that the documents are not merely aspirational statements but are, on the whole, internally coherent and implementable. However, the same analysis exposed deficiencies in long-term strategic planning and in national-level top-level design, indicating that while individual policies function well in isolation, the sector lacks a unifying strategic architecture that would guide it across decades rather than across budget cycles.

These findings carry implications well beyond selenium. The methodological approach, combining topic modeling with instrument coding and consistency scoring, offers a template that could be applied to any policy domain where governments are racing to build an industry around a natural resource or a public health opportunity. The selenium case illustrates a common pattern in Chinese regional policy: strong momentum at the local level, driven by economic incentives and political ambition, but weaker coordination and long-range planning at the national level, which is precisely where strategic resilience is forged.

The authors argue that policymakers should strengthen national top-level design, balance short-term industrial growth against long-term resilience construction, and optimize the configuration of policy tools to stimulate endogenous market vitality. In practical terms, this would mean elevating selenium resource management from an afterthought to a central pillar of policy, building cross-regional coordination mechanisms that treat selenium-rich zones as interconnected systems rather than isolated fiefdoms, and investing in consumer education and demand-side programs that give the supply-side investments somewhere to go.

As China’s selenium-enriched industry matures, the lessons from this analysis will likely resonate with other countries grappling with micronutrient deficiencies embedded in their own soils. The study demonstrates that the health of a policy ecosystem, like the health of the human body, depends on balance: too much emphasis on one dimension, whether industrial expansion or short-term output, starves the others and undermines the whole. What the Chinese experience shows is that quantitative policy analysis can illuminate those imbalances with a precision that qualitative review alone cannot match, offering a data-driven path toward policies that are not only well-intentioned but genuinely well-built.

Subject of Research: Quantitative evaluation of China's selenium-enriched agricultural policies using topic modeling and policy consistency analysis

Article Title: Quantitative analysis of China’s selenium-enriched policy texts: Based on a three-dimensional framework of “theme–instrument–effectiveness”

Article References: Xu, P., Xu, X., Wang, Q., Ye, W., & Luo, J. (2026). Quantitative analysis of China’s selenium-enriched policy texts: Based on a three-dimensional framework of “theme–instrument–effectiveness”. PLOS One, 21(10), e0360381. https://doi.org/10.1371/journal.pone.0360381

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360381

Keywords: selenium, China, policy analysis, LDA topic modeling, PMC index, agriculture, Healthy China, rural revitalization, trace elements, food policy, Quantitative, analysis

The strategy the researchers tested is known as agronomic biofortification, which involves enriching crops with trace elements during cultivation rather than relying on genetic modification or dietary supplements. Conventional biofortification typically applies selenium as selenate and iodine as iodide, either to the soil or directly onto foliage. The problem is that these ionic forms are notoriously inefficient. Iodide applied to soil leaches away quickly, volatilizes into the atmosphere, or gets locked up by soil minerals before roots can absorb it. Selenate competes with sulfate for uptake channels and can be lost through runoff. Foliar sprays improve retention, but the nutrients still sit vulnerably on the leaf surface, exposed to washing off in rain, photodegradation, and inconsistent penetration through the waxy cuticle. The result is inconsistent enrichment from one field, season, or even one application to the next, which makes it difficult to guarantee that a serving of spinach will actually deliver the promised dose of micronutrients.

Chitosan nanoparticles offer a way around these limitations. Chitosan is a biopolymer derived from chitin, the structural material found in crustacean shells, and it is biodegradable, biocompatible, and naturally antimicrobial. When engineered into nanoparticles, chitosan can complex with trace elements and act as a microscopic delivery vehicle. The positively charged amino groups on chitosan bind anions such as selenate and iodide, holding them in a stable reservoir that adheres well to leaf surfaces. Because the particles are nanoscale, they can navigate the stomata and cuticular pathways of leaves far more effectively than dissolved ions alone, promoting gradual uptake rather than rapid loss. The researchers hypothesized that this controlled-release behavior would not only raise the concentration of selenium and iodine in spinach leaves but also stabilize yields when growing conditions turn hostile, since chitosan itself is known to elicit plant defense responses and mild biostimulant effects.

To test this rigorously, the team conducted a field experiment using spinach cultivar Pawnie F1, laid out in a randomized complete block design, the gold standard for agricultural trials because it controls for spatial variation in soil and microclimate. Crucially, they repeated the experiment across three distinct growing seasons in 2025 on the North European Plain: spring, summer, and autumn. This multi-season design matters enormously, because most biofortification studies are conducted in a single season or in greenhouses, leaving open the question of whether results hold up under real-world variability. The comparison pitted conventional selenate and iodide salts against the same nutrients complexed with chitosan nanoparticles, applied as foliar treatments, with the dual selenium-iodine nanoparticle formulation as the centerpiece of the study.

The yield data told a story of seasonal stress and nanoscale resilience. Fresh biomass was highest in spring, reaching 1.62 kilograms per square meter, and lowest in summer, dropping to 1.17 kilograms per square meter, reflecting the heat and light stress that spinach, a cool-season crop, experiences in midsummer. What caught the researchers’ attention was what happened in the less favorable summer and autumn seasons: plots treated with chitosan nanoparticle formulations maintained more stable yields than those treated with ionic salts. This buffering effect suggests that the nanoparticles act not merely as passive nutrient carriers but as biostimulants, helping plants cope with suboptimal conditions. For farmers, this dual benefit, enrichment plus yield stability, could make nanoparticle biofortification economically attractive even before accounting for the reduced fertilizer inputs that higher efficiency implies.

On the enrichment side, both the conventional and nanoparticle treatments significantly increased selenium and iodine concentrations in spinach leaves, confirming that foliar biofortification works in principle. But the efficiency gap was decisive. Averaged across the three seasons, the chitosan-based formulations increased fertilization efficiency for selenium by approximately 41 percent and for iodine by approximately 34 percent relative to the ionic salt formulations. In practical terms, this means farmers could achieve the same nutritional enrichment with substantially less applied nutrient, reducing costs and minimizing the environmental losses that plague conventional fertilization. Importantly, applying selenium and iodine together via the nanoparticles did not reduce the uptake efficiency of either element, demonstrating that simultaneous dual biofortification is technically feasible, something that has been difficult to guarantee with ionic forms because of potential chemical interactions between the two trace elements.

To make sense of the complex dataset, the researchers employed principal component analysis, a statistical technique that condenses many correlated measurements into a few underlying axes of variation. The first principal component, accounting for 36.5 percent of the variability, was dominated by growing season, confirming that weather and photoperiod were the largest sources of variation in the experiment. The second component, explaining 27.5 percent, captured the biofortification effect itself. Within this statistical landscape, the chitosan nanoparticle treatments formed a distinct cluster associated with both higher yields and higher nutrient content, visually separating them from the ionic treatments and reinforcing the conclusion that the nanocarrier fundamentally changes how the crop responds to fertilization.

Food safety, of course, is the make-or-break question for any biofortification technology, and the study addressed it head-on. Spinach is a notorious accumulator of nitrates, which can be converted to nitrites and pose health risks, particularly for infants. The researchers measured nitrate and nitrite levels in the enriched leaves and found that all values remained within the limits set by European Union regulations, regardless of treatment. They then calculated the maximum single-day intake, or MSDI, of selenium and iodine for different consumer groups and confirmed that even the most enriched spinach was safe for all age groups, from children to adults. This dual safety verification, covering both antinutritional compounds and trace element intake, provides the evidence base regulators will need before nanoparticle-fortified crops can reach the market.

The implications stretch well beyond spinach. Micronutrient deficiency, sometimes called hidden hunger, affects an estimated two billion people worldwide, and staple-crop biofortification programs have made progress but often struggle with the same uptake inefficiencies that motivated this study. A biodegradable, shell-derived nanocarrier that boosts efficiency by a third or more while stabilizing yields under stress could be adapted to other leafy vegetables and trace elements, potentially transforming functional food production. The work was supported by Poland’s Implementation Doctorate 2024 program funded by the Ministry of Science and Higher Education, reflecting a deliberate push to move nanotechnology from the laboratory into agricultural practice. As the authors note, this is the first field-based, three-season evidence supporting chitosan nanoparticles for simultaneous selenium and iodine biofortification, and it arrives at a moment when climate volatility is making every advantage in crop resilience and nutrient delivery count. If follow-up studies in other regions and crops replicate these gains, the humble spinach leaf could become a far more powerful vehicle for public health than anyone imagined a decade ago.

Subject of Research: Chitosan nanoparticle-based foliar delivery of selenium and iodine for agronomic biofortification of spinach

Article Title: Nano-delivery of selenium and iodine improves spinach biofortification

Article References: Grochowska, E., Niemiec, M., Komorowska, M., Kula-Maximenko, M., Tan, S. H., Radwan-Pragłowska, J., Mirowski, K., & Gorczyca, A. (2026). Nano-delivery of selenium and iodine improves spinach biofortification. Applied Microbiology and Biotechnology. https://doi.org/10.1007/s00253-026-14073-9

Image Credits: AI Generated

DOI: 10.1007/s00253-026-14073-9

Keywords: chitosan nanoparticles, selenium, iodine, spinach, biofortification, foliar fertilization, micronutrient deficiency, functional food, nanobiotechnology, food safety, crop yield, plant biostimulants

The study, led by Nada M. S. Mohamed together with Adel A. Imam and Miriam Samir Attia from the university’s Dermatology, Venereology and Andrology Department, enrolled forty male patients with psoriasis and followed them for three months. The participants were divided into four groups of ten each: a control group, a control group that also received selenium supplements, a group starting methotrexate alone, and a group starting methotrexate while also taking selenium. Before treatment began and again at the three-month mark, each man provided semen samples for a full laboratory workup, measuring semen volume, sperm concentration, total sperm count, the proportion of normally shaped sperm, and several categories of sperm motility, including progressive, non-progressive, total, and immotile movement.

The researchers also measured something less visible to the microscope but central to their hypothesis: levels of glutathione peroxidase, or GPX, in the seminal fluid. This enzyme, detected here using an enzyme-linked immunosorbent assay, or ELISA, is one of the body’s frontline defenses against reactive oxygen species, the chemically unstable molecules that can shred the lipids, proteins, and DNA of developing sperm. Selenium sits at the very heart of that defense, because the enzyme’s active site depends on selenocysteine, an amino acid that cannot be built without the trace element. In other words, no selenium, no functional GPX, and sperm cells, with their membranes packed vulnerable unsaturated fats, are among the most oxidation-sensitive cells in the body.

The rationale for the trial rests on a well-documented tension. Methotrexate works by inhibiting dihydrofolate reductase, starving rapidly dividing cells of the folate they need to build DNA, which is precisely why it tames the hyperproliferative skin of psoriasis. But the same mechanism, along with downstream effects on tetrahydrobiopterin metabolism and inflammatory signaling pathways such as Jun N-terminal kinase and activator protein-1, has been linked in laboratory and animal studies to the generation of reactive oxygen species. Animal work has repeatedly shown that methotrexate damages testicular tissue, depletes antioxidant enzymes, and impairs sperm production, and selenium supplementation has blunted that damage in mouse models. What has been missing is human evidence from patients actually taking the drug for a skin disease.

After three months, the answer from the methotrexate-only group was sobering. Compared with the other groups, these men showed statistically significant deterioration across a broad swath of semen parameters: semen volume fell, sperm concentration dropped, total sperm count declined, the share of normally shaped sperm shrank, and both progressive and total sperm motility worsened. Their seminal GPX levels also fell significantly, a pattern consistent with the idea that the drug is draining the antioxidant capacity of the reproductive tract. Because semen analysis is notoriously variable between individuals, the study’s design, with each man serving as his own baseline and with untreated and selenium-only comparison groups, strengthens the inference that the changes track with the medication rather than with ordinary biological fluctuation or the underlying skin disease.

The selenium co-administration group told a more nuanced story. Compared with the men on methotrexate alone, those who also took selenium showed improvements in several semen parameters, with the most pronounced benefits appearing in sperm motility, and their seminal GPX levels rose. That alignment matters mechanistically: if methotrexate harms sperm partly by overwhelming antioxidant defenses, then replenishing a key antioxidant enzyme should, in theory, soften the blow, and the motility findings fit that prediction, since the energy-hungry whipping motion of the sperm tail is exquisitely sensitive to oxidative damage to its membrane and mitochondria.

But the shield was far from complete. Even with selenium on board, sperm concentration remained significantly reduced in the methotrexate-plus-selenium group compared with the control groups. Sperm concentration reflects the output of spermatogenesis itself, the roughly seventy-day assembly line inside the seminiferous tubules, and the finding suggests that selenium’s antioxidant support may protect the function and survival of mature sperm without fully protecting the stem cell-driven production line from methotrexate’s antiproliferative effects. The authors are careful on this point: selenium co-administration was associated with potentially beneficial changes in selected parameters, but it did not prevent all of the methotrexate-associated changes.

That caution extends to the entire enterprise, and it is worth underlining for readers tempted to rush to the supplement aisle. This was a pilot study, small in size with ten men per group, retrospective in its trial registration, and explicitly hypothesis-generating in the authors’ own framing. The findings do not establish therapeutic efficacy, and they do not prove a causal chain running from selenium supplementation through GPX changes to semen outcomes. Selenium itself is a double-edged micronutrient: the window between deficiency, adequacy, and toxicity is narrow, and excessive intake has been linked in some studies to its own reproductive and systemic harms. Larger, adequately powered clinical trials, the authors write, are required to confirm the findings and determine their clinical relevance before any recommendation can be made to men on methotrexate.

The study also lands in the middle of an evolving conversation about methotrexate and male fertility more broadly. Not all human evidence points the same way: a prospective cohort study of men with immune-mediated inflammatory diseases, the iFAME-MTX study, found that low-dose methotrexate did not appear to compromise semen parameters or sperm DNA in men actively trying to father children, and other work in inflammatory bowel disease reached similar conclusions. The new Egyptian trial, by contrast, measured significant deterioration over just three months in psoriasis patients starting therapy. Differences in disease type, dose, duration, baseline health, and the sensitivity of the measurements may all contribute, which is exactly why the field needs larger and longer studies rather than a single decisive verdict.

What the pilot study does deliver is a concrete, testable hypothesis and a human data point where almost none existed before. It confirms in living patients that methotrexate therapy is accompanied by measurable declines in semen quality and seminal antioxidant enzyme levels, it shows that selenium supplementation is associated with partial protection, most visibly for sperm motility and GPX levels, and it honestly reports where the protection fails. For the millions of men worldwide who take methotrexate for psoriasis, rheumatoid arthritis, and other inflammatory diseases, and for the dermatologists and rheumatologists who prescribe it, that combination of promise and limitation is not a footnote. It is the beginning of an evidence base that could eventually change how fertility is discussed in the clinic, turning an anxious unknown into a manageable, measurable risk, and perhaps one day into a risk that a simple, carefully dosed trace element can help blunt.

Subject of Research: Selenium supplementation as a potential protective measure against methotrexate-induced spermatotoxicity in male psoriasis patients

Article Title: Role of selenium supplementation in methotrexate-associated spermatotoxicity in patients with psoriasis: a pilot clinical study

Article References: Mohamed, N. M. S., Imam, A. A., & Samir Attia, M. (2026). Role of selenium supplementation in methotrexate-associated spermatotoxicity in patients with psoriasis: a pilot clinical study. Archives of Dermatological Research, 318(1), Article 521. https://doi.org/10.1007/s00403-026-04986-w

Image Credits: AI Generated

DOI: 10.1007/s00403-026-04986-w

Keywords: selenium, methotrexate, psoriasis, male fertility, spermatotoxicity, glutathione peroxidase, oxidative stress, semen parameters, sperm motility, antioxidants, dermatology, pilot study

The research team, led by Tong Sun and Xifeng Wu of Zhejiang University School of Medicine in Hangzhou, China, set out to address a persistent gap in nutritional epidemiology. Individual antioxidants such as vitamins A, C, and E have each shown hints of protective potential against cancer, but trials of single-nutrient supplements have repeatedly disappointed, and the US Preventive Services Task Force has cautioned against using vitamin and mineral supplements for cancer prevention. What has remained unclear is whether the total antioxidant load of a whole diet, delivered through food rather than pills, is associated with lung cancer risk in a way that can be measured and replicated across populations.

To answer that question, the investigators designed a two-pronged study. The first component was a case-control analysis nested within the Healthy Zhejiang One Million People (HOPE) study, a large cohort established in China, with participants enrolled between 2022 and 2024. Lung cancer patients were compared with cancer-free control participants drawn from the same source population. The second component was a prospective cohort analysis of participants in the UK Biobank, a vast biomedical database of half a million British adults. Baseline dietary and health data for the UK Biobank participants were collected between 2009 and 2010, and the researchers followed them for disease outcomes through December 19, 2022. Using two different populations, two different study designs, and two different statistical frameworks gave the team a way to test whether any observed association would survive independent scrutiny.

The technical heart of the study lies in how dietary antioxidant exposure was quantified. Rather than examining nutrients one at a time, the researchers constructed two composite indices from the intake of six vitamins and minerals, as reported on food frequency questionnaires. The first, the composite dietary antioxidant index (CDAI), aggregates standardized intake values of several antioxidant nutrients into a single score reflecting the overall antioxidant capacity of the diet. The second, the dietary antioxidant quality score (DAQS), takes a different approach, evaluating whether participants meet recommended intake thresholds for key antioxidant nutrients. Both indices were divided into tertiles, allowing the researchers to compare people in the highest third of antioxidant intake with those in the lowest third, while adjusting statistically for total energy intake and other potential confounders.

The results were striking in their consistency. In the HOPE case-control study, participants in the highest tertile of the CDAI had 57 percent lower odds of lung cancer than those in the lowest tertile, with an odds ratio of 0.43 and a 95 percent confidence interval of 0.28 to 0.65, a statistically significant result. The DAQS told a similar story in the same population: the highest tertile carried an odds ratio of 0.54, meaning 46 percent lower odds, with a confidence interval of 0.36 to 0.82. In the UK Biobank cohort, where the researchers used Cox proportional hazards models to account for the passage of time, the pattern held. High CDAI was associated with a hazard ratio of 0.59, and high DAQS with a hazard ratio of 0.56, both statistically significant. In other words, across both indices and both populations, people with the most antioxidant-rich diets developed lung cancer at roughly 40 to 60 percent lower rates than those with the least.

The biological rationale for such an association rests on the role of reactive oxygen species in carcinogenesis. Oxidative stress arises when the production of reactive oxygen species outpaces the body’s antioxidant defenses, damaging DNA, lipids, and proteins. In lung tissue, this damage can create DNA adducts and mutations that initiate and drive malignant transformation, and oxidative stress is also entwined with chronic inflammation, another recognized cancer-promoting process. Dietary antioxidants, including vitamins A, C, and E along with trace minerals such as selenium, zinc, manganese, and copper, function as cofactors and radical-scavenging agents in the enzymatic and non-enzymatic systems that keep oxidative damage in check. Because these nutrients interact, sometimes synergistically and sometimes antagonistically, many researchers argue that their combined dietary presence, rather than any single compound, determines their net effect on cellular redox balance.

Importantly, the associations were robust to the team’s sensitivity and subgroup analyses. The researchers examined whether the relationship differed across strata of the study populations and whether alternative analytical choices changed the conclusions, and the protective pattern remained consistent throughout. This kind of internal stability matters in nutritional epidemiology, a field notorious for findings that evaporate under scrutiny. The convergence of a case-control design, which is efficient but vulnerable to recall bias, with a prospective cohort design, in which diet is measured before disease develops, provides a form of triangulation that neither design could achieve alone. The fact that two distinct composite indices, built on different scoring logic, pointed in the same direction further strengthens the signal.

Still, the authors and outside observers alike must weigh the usual caveats of observational research. Food frequency questionnaires depend on self-report, and people who eat more antioxidant-rich foods, typically fruits, vegetables, nuts, and whole grains, tend to differ from other people in many ways that influence cancer risk, including smoking behavior, physical activity, and socioeconomic circumstances. Although the study applied multivariable adjustment to account for such factors, no statistical model can eliminate confounding entirely. Reverse causation is a particular concern in the case-control component, since lung cancer patients may have altered their diets before enrollment. The prospective UK Biobank analysis mitigates that concern, but even there, unmeasured lifestyle differences could contribute to the observed gradient. The findings establish association, not causation, and the authors note that the data supporting the work are available from the corresponding author upon reasonable request.

What the study does offer is a reframing of how dietary prevention might be approached. Rather than chasing individual supplement trials that have largely failed to deliver, the composite-index approach captures the antioxidant profile of the whole diet, aligning with the broader evidence that overall dietary patterns, such as the Mediterranean diet, are more predictive of health outcomes than isolated nutrients. For clinicians and public health planners, the results suggest that encouraging at-risk individuals, including smokers and former smokers, to build diets naturally rich in antioxidant capacity could be a meaningful component of lung cancer prevention strategies. The researchers emphasize that elevated dietary antioxidant consumption should be viewed as a protective factor worth reinforcing, while acknowledging that diet is one strand in a web of risk that includes tobacco exposure, occupational carcinogens, air pollution, and genetic susceptibility. As lung cancer remains one of the deadliest malignancies worldwide, a low-cost, food-based intervention that correlates with a reduction in risk of this magnitude will demand closer attention, and ideally, further prospective validation in additional populations.

Subject of Research: The association between overall dietary antioxidant capacity and lung cancer risk in two observational cohorts

Article Title: Association between overall dietary antioxidant capacity and lung cancer risk: findings from two observational studies

Article References: Sun, T., Zhang, L., Luo, X., Wang, L., Xue, Q., Song, W., Li, W., Tu, H., & Wu, X. (2026). Association between overall dietary antioxidant capacity and lung cancer risk: findings from two observational studies. European Journal of Epidemiology. https://doi.org/10.1007/s10654-026-01474-3

Image Credits: AI Generated

DOI: 10.1007/s10654-026-01474-3

Keywords: lung cancer, dietary antioxidants, composite dietary antioxidant index, UK Biobank, HOPE cohort, oxidative stress, cancer prevention, nutritional epidemiology, case-control study, prospective cohort, vitamins, selenium