The research team, led by Lianshuai Zheng and colleagues, recruited 51 healthy pregnant women at 6 to 8 weeks of gestation, confirming early pregnancy through ultrasound visualization of the fetal heart and embryonic bud. Participants were followed prospectively throughout their pregnancies, with pregnancy complications, delivery outcomes, and neonatal health assessed at day 42 after birth. To ensure that the micronutrient data reflected healthy physiology rather than disease-related distortions, the final analysis was restricted to 43 women who completed all assessments and experienced uncomplicated pregnancies with favorable outcomes for both mother and child.

What sets this study apart from much of the existing literature is its longitudinal design combined with high-resolution analytical chemistry. Whole-blood trace elements were quantified using inductively coupled plasma mass spectrometry, or ICP-MS, a technique capable of detecting metals and metalloids at extremely low concentrations with high accuracy. Serum vitamins, meanwhile, were measured with ultra-high-performance liquid chromatography coupled to tandem mass spectrometry, known as UHPLC-MS/MS, which allows precise separation and quantification of individual vitamin species in complex biological matrices. Blood samples were collected at three defined time points: the first trimester at an average of 12.3 weeks of gestation, the second trimester at 25.6 weeks, and the third trimester at 32.7 weeks.

The results revealed a striking choreography of rising and falling concentrations. Copper, calcium, and vitamin D all peaked during the second trimester before declining thereafter. This pattern is physiologically plausible: copper plays a central role in fetal development and maternal iron metabolism, calcium demand surges as fetal skeletal mineralization accelerates, and vitamin D status is closely tied to calcium homeostasis. The mid-pregnancy peak in these three analytes suggests a coordinated biological response to the heightened demands of the second trimester, when fetal growth is rapid and placental transfer of minerals intensifies.

In contrast, iron, zinc, magnesium, and lead reached their lowest concentrations, or nadir, during the second trimester. The dip in iron is consistent with the well-documented hemodilution of pregnancy, in which plasma volume expands faster than red cell mass, effectively diluting circulating iron even as total body iron may be conserved. Zinc and magnesium follow similar trajectories, likely reflecting the same dilutional effect combined with active fetal uptake. The parallel decline in lead is noteworthy, because it suggests that maternal blood lead concentrations may fall as pregnancy progresses, possibly through redistribution into maternal tissues and the fetal compartment, though the study was not designed to test mechanisms directly.

Not every micronutrient followed a peak-and-valley pattern. Manganese and vitamins E and K increased progressively throughout gestation, rising steadily from the first trimester through the third. Vitamin E, a lipid-soluble antioxidant, is known to travel with lipids in the bloodstream, and lipid concentrations naturally rise in pregnancy, which may partly explain the upward trend. Vitamin K is essential for blood coagulation, and the hypercoagulable state of pregnancy, which prepares the body for delivery, could drive increased demand and circulating levels. Manganese serves as a cofactor for numerous enzymes involved in metabolism and antioxidant defense, and its gradual accumulation may reflect both dietary intake and fetal developmental needs.

The B vitamins told a different story. Several members of this water-soluble family showed an overall downward trend across gestation, a pattern that may reflect increasing utilization by the fetus and placenta as well as the expanding maternal blood volume. Vitamin B12, however, remained relatively stable throughout pregnancy, standing out as an exception to the general decline. This stability is clinically relevant because B12 deficiency during pregnancy has been associated with adverse neurodevelopmental outcomes, and a stable baseline suggests that maternal stores or intake were sufficient to maintain circulating levels in this healthy cohort.

The authors emphasize that these findings demonstrate clear trimester-specific changes in maternal micronutrient levels during healthy pregnancy, a point with direct clinical implications. Many laboratories currently interpret micronutrient results in pregnant women using reference intervals derived from non-pregnant populations or from pooled data that do not distinguish between trimesters. If copper, calcium, and vitamin D naturally peak in mid-pregnancy while iron, zinc, and magnesium naturally dip, then applying a single static reference range could misclassify healthy women as deficient or excessive at particular stages of gestation. Trimester-specific reference intervals would allow clinicians to distinguish physiological adaptation from genuine deficiency or toxicity with far greater accuracy.

The regional dimension is equally important. Micronutrient status is shaped by local diet, soil and water composition, supplementation practices, and environmental exposures, all of which vary considerably across geographic areas. Lianyungang, as a coastal city with its own dietary and environmental profile, may not be representative of other regions of China or of other countries. The study’s authors therefore frame their data as preliminary evidence to inform the establishment of region-specific and trimester-specific reference intervals and deficiency thresholds for micronutrients in healthy pregnant women, rather than as universal standards.

Several caveats temper the conclusions. The sample size of 43 women in the final analysis is relatively small, which limits the statistical power to detect subtle changes and to stratify results by factors such as maternal age, parity, diet, or supplementation habits. The cohort was restricted to healthy women with uncomplicated pregnancies, so the trajectories observed here may differ in women with gestational diabetes, hypertensive disorders, anemia, or other complications. Nevertheless, the longitudinal design, the use of state-of-the-art analytical methods, and the careful confirmation of favorable maternal and neonatal outcomes lend credibility to the observed patterns. As the authors note, these longitudinal data provide a foundation upon which larger, multi-center studies can build to refine micronutrient reference standards for pregnancy, ultimately supporting more precise nutritional monitoring and care for expectant mothers worldwide.

Subject of Research: Trimester-specific fluctuations of maternal micronutrients during healthy pregnancy

Article Title: Fluctuations of micronutrients during pregnancy in Lianyungang, Jiangsu, China: A prospective longitudinal cohort study

Article References: Zheng, L., Xu, X., Rong, X., Luo, J., Chen, G., & Zhao, C. (2026). Fluctuations of micronutrients during pregnancy in Lianyungang, Jiangsu, China: A prospective longitudinal cohort study. PLOS One, 21(10), e0360813. https://doi.org/10.1371/journal.pone.0360813

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360813

Keywords: pregnancy, micronutrients, trace elements, vitamins, longitudinal cohort study, ICP-MS, UHPLC-MS/MS, trimester-specific reference intervals, maternal health, fetal development, PLOS One, Lianyungang

Infant malnutrition remains a serious problem in DR Congo, where many babies are fed thin porridges made from maize, cassava or sorghum that are low in protein and micronutrients. The study, led by researchers at the University of Lubumbashi, set out to find whether dagaa, which is rich in protein, calcium, iron and zinc, could be used to improve the nutritional quality of these staple foods.

The team developed two enriched porridge formulations, one containing 40 percent dagaa and another containing 20 percent dagaa, alongside a control porridge made only from cereals. They then measured the protein, energy, calcium, iron and zinc content of each porridge and compared the results with recommended nutrient intakes for infants aged 6 to 23 months.

The results showed that the porridge containing 40 percent dagaa provided 33 grams of protein per 100 grams, more than three times the amount in the cereal-only control. It also supplied 82 percent of the recommended calcium intake, 55 percent of the recommended iron intake and 60 percent of the recommended zinc intake for infants in a single 100-gram serving. The porridge with 20 percent dagaa performed better than the control but less well than the 40 percent formulation.

The researchers also assessed how acceptable the enriched porridges were to mothers and their babies. In sensory tests with 82 mother-infant pairs, the cereal-only porridge was preferred, but more than two-thirds of mothers said they would be willing to feed the dagaa-enriched porridge to their babies. The babies themselves ate similar amounts of the enriched and control porridges, suggesting that the dagaa formulations were well tolerated.

The study also examined the safety and stability of the enriched porridges over six months of storage. The dagaa porridges remained free from microbial contamination throughout the storage period, and their nutritional content stayed stable, indicating that they could be produced and stored locally without specialized equipment.

The findings suggest that dagaa could be a practical and affordable way to improve infant nutrition in DR Congo and other low-income countries. The fish is already widely consumed, is available year-round and requires no processing beyond sun-drying, making it an accessible ingredient for local porridge production.

However, the researchers note that the enriched porridges did not meet all recommended nutrient levels, particularly for iron and zinc, and that further work is needed to optimize the formulations. They also recommend that future studies assess the bioavailability of the minerals in dagaa and evaluate the long-term effects of dagaa-enriched porridges on infant growth and development.

The study adds to growing evidence that small dried fish could play an important role in tackling infant malnutrition in low-income countries. Similar approaches have been tested in Malawi, where dried fish was used to enrich porridges for babies, and in Bangladesh, where small fish have been promoted as a source of micronutrients for young children.

The researchers conclude that dagaa-enriched porridges could be a valuable addition to infant feeding programs in DR Congo, offering a locally available, affordable and nutritionally dense ingredient that could help reduce the burden of infant malnutrition in one of the world’s poorest countries.

The formulation strategy used in the study reflects a growing recognition that nutrition interventions in resource-limited settings must balance scientific rigor with local practicality. Rather than importing fortified products from abroad, the researchers applied linear programming, an optimization technique that calculates the least-cost combination of ingredients while still meeting predefined nutrient targets. This approach, first adapted for complementary food design in sub-Saharan Africa more than a decade ago, allows formulators to work backward from international recommendations, in this case the World Food Programme’s guidance for complementary foods, and to anchor every decision in ingredients that families in South Kivu already buy and prepare. The targets themselves were deliberately ambitious: the team aimed for nutrient levels equivalent to twice the recommended nutrient intake per 100 grams of dry flour, a threshold recommended precisely because young children in high-burden settings may consume only around 50 grams of complementary food per day, meaning each serving must carry a concentrated nutritional payload.

The choice of processing methods was equally deliberate. Roasting, the primary treatment applied to the maize, soybeans, and dagaa, is a traditional technique across much of Africa that requires no electricity, pressurized equipment, or imported inputs. Beyond its cultural familiarity, roasting serves several technical purposes. For soybeans, heat treatment inactivates trypsin inhibitors, naturally occurring compounds that otherwise interfere with protein digestion and reduce the biological value of the legume. For dagaa, roasting at a lower temperature for a shorter duration reduces microbial loads and softens the characteristic fishy odor that can limit acceptance among caregivers unaccustomed to strongly flavored infant foods. For maize, roasting develops the brown color and toasted aroma associated with locally prepared flours, which likely contributed to the sensory familiarity of the final porridges even as their composition changed substantially.

The nutritional rationale for including small dried fish rests on a distinctive biological feature: when consumed whole, as dagaa typically is, the bones, heads, and flesh are all eaten together. This makes small fish unusually dense in calcium, since the skeletal tissue is ingested directly rather than discarded as it would be with larger species. Studies across several countries in sub-Saharan Africa and South Asia have found that powdered whole small fish can deliver iron, zinc, and calcium at levels approaching those of commercially manufactured micronutrient supplements, at a fraction of the cost. Dagaa itself occupies a specific ecological niche in Lake Tanganyika, one of the most productive fisheries in Africa, where it is harvested in large volumes and traded widely across the region. Its high reproductive rate and the fact that harvests in many areas remain below maximum sustainable yield suggest that scaling up its use in infant foods would not necessarily strain the fishery, though sustainable management remains an important consideration as demand grows.

The findings from South Kivu align with a body of evidence accumulated across the continent. In Ghana, Ethiopia, Tanzania, and Zambia, researchers have tested formulations incorporating locally available small fish species into staple-based complementary foods, generally reporting improvements in micronutrient content without unacceptable losses in palatability. Work in Malawi using usipa, another small sardine-like species, demonstrated that maize-soybean-fish blends could improve both nutritional quality and acceptability among infants and their caregivers. These converging results from different countries and different fish species strengthen the case that the approach is not dependent on one particular fishery or one particular grain combination, but reflects a generalizable principle: whole dried small fish can serve as a low-cost, locally sourced vehicle for delivering animal-source nutrients into diets that are otherwise dominated by cereals.

The significance of animal-source foods in infant nutrition extends beyond individual micronutrients. Evidence accumulated over several decades indicates that children whose diets include even modest amounts of animal-source foods tend to grow better than those fed exclusively plant-based diets, a difference attributed not only to the bioavailability of minerals and the quality of protein but also to nutrients such as vitamin B12, preformed vitamin A, and long-chain omega-3 fatty acids that are absent or poorly available in plant staples. In settings where fortified commercial products are unaffordable or unavailable, whole small fish may be one of the few practical ways to introduce these nutrients into the diets of children in the critical window between six months and two years of age, when growth faltering and micronutrient deficiencies become most pronounced.

The microbiological stability observed over six months of storage deserves particular attention in the context of the study region. Persistent armed conflict in eastern Democratic Republic of Congo has disrupted supply chains, limited access to refrigeration, and made consistent food distribution difficult. A complementary food that remains safe and nutritionally stable at ambient temperature for months, prepared with equipment no more sophisticated than a hammer mill and a simple roaster, addresses these constraints directly. This durability also matters for household-level production, where flour may be prepared in batches and consumed gradually rather than purchased fresh for each meal.

At the same time, the sensory results highlight a genuine challenge that nutrition programs must confront. The preference for the cereal-only porridge among mothers, even as most expressed willingness to feed the enriched versions to their infants, suggests that familiarity and taste expectations shape caregiver choices in ways that nutritional information alone may not overcome. The fact that infants themselves consumed similar quantities of enriched and control porridges is encouraging, since young children’s acceptance is ultimately what determines intake, but sustained adoption will depend on convincing caregivers that the enriched products are both safe and desirable. Previous interventions in the region suggest that repeated exposure, community engagement, and integration with existing feeding practices can gradually shift preferences, particularly when the unfamiliar ingredient is one that families already recognize and use in other dishes.

The remaining gaps identified by the researchers point toward the next stages of evidence needed before such formulations can be scaled. Mineral bioavailability in whole-fish preparations, which may be influenced by antinutritional compounds in the cereal components and by the form in which the minerals are bound, has not been directly measured in this context. Nor have the longer-term effects on growth, hemoglobin status, or developmental outcomes been established through controlled trials. These questions matter because nutrient targets on paper do not automatically translate into nutritional benefits for children, and because the iron and zinc shortfalls observed in the formulations suggest that further optimization, whether through adjusted ingredient ratios, additional fortificants, or complementary dietary sources, may still be required to fully meet infant requirements.

Subject of Research: Nutrition

Article Title: Nutritional and Sensory Evaluation of Complementary Foods Developed From Staple Grains and Dried Dagaa Fish (Stolothrissa tanganicae)

Article References: Nabuholo, M. A., Mama, O. M., Diouf, A., Bahizire, E., Alexis, G. K., Rodrigue, C. N., & Idohou‐Dossou, N. (2026). Nutritional and Sensory Evaluation of Complementary Foods Developed From Staple Grains and Dried Dagaa Fish ( Stolothrissa tanganicae ). Food Science & Nutrition, 14(10), Article e72463. https://doi.org/10.1002/fsn3.72463

Image Credits: AI Generated

DOI: 10.1002/fsn3.72463

Keywords: infant nutrition, dagaa, DR Congo, malnutrition, porridge, food fortification, micronutrients, Nutritional, Sensory, Evaluation, Complementary, Foods

The research team, led by Sarah L. H. Kamhout of the Department of Psychology at Brigham Young University, recruited 80 adolescents between the ages of 14 and 18 from the general community. Participants completed detailed 24-hour dietary recalls using the National Cancer Institute’s Automated Self-Administered 24-hour dietary assessment tool, known as ASA-24, on two to three randomly assigned days that included both weekdays and weekends. The tool captured intake of 26 different micronutrients, ranging from familiar players like calcium, iron, and vitamin D to less-studied carotenoids such as lycopene, lutein, and zeaxanthin. Participants were notified of their assigned recall day only on the day itself, a design choice intended to prevent them from altering their eating habits in response to being observed.

Sleep was measured with unusual rigor for a study of this kind. Each participant wore a wrist-worn actigraph for 7 to 20 days, providing objective data on sleep onset time, sleep midpoint, total sleep duration, sleep efficiency, and wake after sleep onset, a measure known as WASO. Because adolescents are known to be unreliable reporters of their own sleep habits, actigraphy readings were cross-verified with daily sleep diaries. The Sadeh algorithm, a validated method for converting movement data into sleep-wake states, was used to score each night. Sleep efficiency was calculated as the ratio of time asleep to time in bed, and all time-based variables were converted to minutes after midnight to avoid circular calculations.

Beyond nightly sleep, the study also probed more trait-like dimensions of sleep health. Participants completed the Morningness-Eveningness Questionnaire to assess chronotype, their innate preference for early or late sleep and wake times, and the Epworth Sleepiness Scale for Children and Adolescents to gauge daytime sleepiness. Most notably, each subject underwent a six-hour dim light melatonin onset protocol, or DLMO, in the laboratory. After a three-to-five-day at-home sleep stabilization period, saliva samples were collected every 30 to 45 minutes under light levels below 5 lux, beginning five hours before and ending one hour after each participant’s preferred bedtime. DLMO was defined as the moment salivary melatonin concentrations exceeded 4 picograms per milliliter, a threshold previously validated in adolescents. The gap between DLMO and average sleep onset, called the phase angle, served as a measure of circadian alignment, with values between two and four hours considered clinically aligned.

The statistical approach was equally careful. Because dietary reference intakes differ between males and females due to distinct biological and metabolic needs, all analyses were performed separately by sex. The researchers used mixed effects models with random by-participant intercepts to account for multiple dietary intakes per participant, then applied backwards step-wise model fitting to remove micronutrients that did not improve overall model fit. Variance inflation factors below five confirmed low collinearity in all final models, and p-values were corrected for multiple comparisons using the Benjamini-Hochberg false discovery rate procedure, applied separately for daily and averaged models.

Against the researchers’ initial hypotheses, no single micronutrient emerged as significantly associated with improved sleep health across all models. Yet two nutrients showed the most consistent positive signals. Potassium, with coefficients ranging from -0.03 to 0.004 and p-values below 0.05, was linked to increased same-night sleep efficiency in both males and females, and to earlier sleep onset in females. Retinol, a specific chemical form of vitamin A, showed associations with better sleep efficiency in females and earlier sleep midpoint and onset in males, with coefficients ranging from -0.20 to 0.01 and p-values below 0.05. These findings echo a classic double-blind, placebo-controlled crossover study in nine adult males on potassium-deficient diets, where supplementation improved sleep efficiency and consolidation, and more recent work linking lower urinary potassium excretion to greater daytime sleepiness in adults.

On the other side of the ledger, zinc and vitamin B12 were the micronutrients most consistently linked with negative sleep outcomes. Zinc, with coefficients ranging from -0.54 to 3.51 and p-values below 0.10, was associated with later sleep onset in males on the same night, reduced average sleep efficiency in males, and increased daytime sleepiness in both sexes. Vitamin B12, with coefficients ranging from -0.96 to 7.22 and p-values below 0.05, was linked to later sleep midpoint in males, reduced sleep efficiency in females, and increased wake after sleep onset in males. Notably, mean vitamin B12 intake in the sample surpassed the recommended daily allowance roughly three-fold for males and five-fold for females, a pattern consistent with prior research suggesting vitamin B12 can have an alerting effect that delays sleep onset and shortens sleep duration.

The dietary data itself revealed a troubling picture of adolescent nutrition. Less than 2 percent of youth ages 14 to 18 meet recommended vegetable intake guidelines according to national survey data, and only 2.9 percent of children and adolescents meet daily whole grain requirements. In this sample, average intake of sodium, copper, selenium, vitamin C, niacin, vitamin B6, vitamin K, and vitamin B12 exceeded recommended daily intake ranges for both sexes, while average intake of calcium, magnesium, potassium, vitamin D, and vitamin A fell below recommended ranges. Over half of participants did not meet recommended vitamin D intake, a deficiency consistently associated with decreased sleep duration and poorer sleep efficiency in children and adolescents. Iron, frequently tied to sleep disorders such as restless legs syndrome in prior research, showed no significant associations in this study, possibly because the female sample was on average below the recommended daily allowance for iron, making it difficult to detect effects of adequate or excess consumption.

The researchers emphasize that their findings are exploratory signals rather than established causal relationships. The cross-sectional design limits causal inference, though the day-to-night matching of dietary intake with same-night sleep helps establish temporal precedence in some analyses. Self-reported dietary recalls introduce potential recall and desirability biases, and the ASA-24, while demonstrating strong agreement with interviewer-administered recalls, is not a perfect measure of true intake. Absorption and metabolism of micronutrients also vary by individual, influenced by storage levels, interactions between nutrients, and whether intake comes from food or supplements. Carotenoids, for instance, are absorbed less efficiently than retinol, and people with low stores of vitamins A, calcium, and iron increase their ability to absorb more of these nutrients, meaning individual adolescents may have exhibited different patterns of absorption related to their specific consumption patterns.

Despite these limitations, the study represents the first broad examination of micronutrient intake and sleep health in adolescents, a population where nearly 70 percent fail to obtain the recommended 8 to 10 hours of sleep and over 40 percent report sleeping less than 7 hours per night. The findings suggest that sleep may be sensitive to day-to-day shifts in potassium intake, that different chemical forms of vitamin A may play distinct roles in sleep timing, and that zinc and vitamin B12 warrant closer scrutiny for their potential negative associations with sleep during adolescence. The researchers call for experimental and longitudinal designs to clarify causal pathways and for interventions tailored to individual intake patterns, timing of consumption, and interactions between multiple nutrients. No universal, one-size-fits-all dietary solution for improving adolescent sleep emerged from this work, but the study opens a promising avenue for understanding how the food on a teenager’s plate might ripple through the architecture of their night.

Subject of Research: Nutrition and Sleep Science

Article Title: In search of vitamin sleep: cross-sectional analysis of vitamin and mineral intake and sleep health outcomes in adolescents

Article References: Kamhout, S. L. H., Bellini, S. G., Luke, S. G., Homer, K. J., Broadbent, M., & Duraccio, K. M. (2026). In search of vitamin sleep: cross-sectional analysis of vitamin and mineral intake and sleep health outcomes in adolescents. Frontiers in Nutrition, 13, Article 1978612. https://doi.org/10.3389/fnut.2026.1978612

Image Credits: AI Generated

DOI: 10.3389/fnut.2026.1978612

Keywords: adolescent sleep, micronutrients, potassium, retinol, zinc, vitamin B12, circadian rhythm, DLMO, actigraphy, sleep health, search, vitamin

The review begins with a principle that has governed plant nutrition for decades. Essentiality means that the absence of even one essential plant nutrient element renders growth or reproduction impossible. By convention, the essentials for plant nutrition include carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, zinc, manganese, copper, boron, chlorine, molybdenum, nickel, and, to the extent that it is accepted as an essential mineral element, cobalt. On a dry-weight basis, the elements derived from air and water, namely carbon, hydrogen and oxygen, account for roughly 94 to 96 percent of plant biomass. The primary macronutrients make up about 2 to 3.5 percent, the secondary macronutrients about 0.5 to 1.5 percent, and the micronutrients less than 0.1 percent of dry mass. Despite their small share, the authors emphasize, these elements sustain light harvesting, water oxidation, electron transport, ATP and NADPH production, the carbon reactions, and the integration of photosynthesis with the metabolism of the whole plant.

To understand why, it helps to revisit the architecture of photosynthesis. Two pigment-protein systems embedded in the thylakoid membrane of the chloroplast, Photosystem I and Photosystem II, mediate light absorption, excitation energy transfer, primary photochemistry, electron transfer, the oxidation of water, and the reduction of NADP+ to NADPH. In addition to electron transfer, several membrane complexes release protons into the thylakoid lumen, generating a proton gradient that is exploited by ATP synthase to produce ATP. The NADPH and ATP are then used to convert carbon dioxide into carbohydrates via the C3 and C4 pathways, packing energy into sugar bonds. Each of these steps depends on specific elements. Magnesium sits at the center of every chlorophyll molecule, both in the antenna complexes that harvest sunlight and in the reaction-center chlorophylls of Photosystems I and II that drive electron transfer from water to NADP+. Manganese and calcium form the Mn4CaO5 cluster of Photosystem II, the site of water splitting and oxygen evolution. Iron and sulfur together build the iron-sulfur clusters of the cytochrome b6f complex, Photosystem I and ferredoxin, while copper is the redox cofactor of plastocyanin, the mobile carrier that transfers electrons from the cytochrome b6f complex to Photosystem I.

The air- and water-derived elements play roles that go beyond serving as the molecular framework of substrates and products. Carbon is the backbone of all organic molecules, and in plants it is primarily acquired from atmospheric carbon dioxide, which diffuses into leaves through stomata and serves as the inorganic carbon source for the Calvin-Benson-Bassham cycle. But the bicarbonate ion is also a critical cofactor of Photosystem II, regulating the photosynthetic electron transport chain. Hydrogen and oxygen make up the water that is split during water oxidation, the core of oxygenic photosynthesis because it generates molecular oxygen. Furthermore, the hydrogen ions released during water oxidation and other steps play essential roles in generating the pH gradient across the thylakoid membrane that leads to ATP production. The stoichiometry is demanding: the fixation of six carbon dioxide molecules via the Calvin-Benson-Bassham cycle, corresponding to the synthesis of one glucose equivalent, requires 18 ATP and 12 NADPH molecules, while the oxidation of two water molecules at Photosystem II supplies four electrons that drive the formation of two NADPH molecules and a proton-motive force sufficient to synthesize up to three ATP molecules.

Nitrogen occupies a special place among the macronutrients because its influence on photosynthesis does not saturate the way most mineral nutrients do. Leaf nitrogen content shows an approximately proportional relationship with photosynthetic capacity across a wide physiological range, a relationship that arises because a large fraction of nitrogen is invested directly in the photosynthetic apparatus within the leaf, particularly in rubisco and the thylakoid proteins of the electron transport chain. The capacity for electron transport in the chloroplast is directly proportional to cytochrome f content, and nitrogen assimilation is integral to carbon assimilation. Nitrogen is a constituent of amino acids, proteins, chlorophyll, nucleic acids, NADPH and ATP, and it is a building block of the enzymes of the Calvin-Benson-Bassham cycle. Nitrogen use and allocation differ substantially between C3 and C4 plants, a distinction with consequences for how crops respond to fertilization under different climates.

Phosphorus and potassium complete the primary macronutrient picture with distinct technical roles. Phosphorus is a constituent of inorganic phosphate and of the key energy-transfer molecules NADP, NADPH, ADP and ATP, and it is embedded in the thylakoid membrane as phospholipids. Under phosphorus deficiency, the photosynthetic electron transport chain is disrupted, ATP synthase activity is restricted, and carbon dioxide fixation is reduced, linking phosphorus to both the light reactions and the carbon reactions. Potassium, meanwhile, is involved in transmembrane transport and enzyme activation. Ion transporters and potassium channels are integrated into the thylakoid, where a potassium channel activates plastoquinone and a potassium/hydrogen antiporter stimulates electron transport. Energy conversion may be affected by modulation of acidification through thylakoid and lumen potassium and chloride channeling. Potassium also facilitates carbon dioxide diffusion into chloroplasts and is involved in the transport of photosynthates throughout the plant.

The secondary macronutrients and micronutrients reveal how tightly the light and carbon reactions are coupled through metal chemistry. Calcium is part of the Mn4CaO5 cluster required for water oxidation and oxygen evolution, and it is implicated, by still unknown mechanisms, in the regulation of electron transfer and carbon reaction proteins. Magnesium is required for key Calvin-Benson-Bassham cycle enzymes and for rubisco activation, and all reactions involving ATP require magnesium ions. Sulfur is associated with iron in the Rieske iron-sulfur protein of the cytochrome b6f complex and is part of several Photosystem I components and ferredoxin, and it is a component of methionine and cysteine, two amino acids central to photosynthetic protein complexes. Zinc is a cofactor of the copper/zinc superoxide dismutase and carbonic anhydrase, contributing to carbon metabolism. Boron is required for the regulation of carbohydrate metabolism in the carbon reactions. Molybdenum is present in four metalloenzymes that catalyze redox reactions in plants, particularly those involved in nitrogen assimilation, and it improves chloroplast configuration and increases chlorophyll content. Chlorine, in the form of chloride ions, is required for Photosystem II activity and is involved in the regulation of proton transfer during water oxidation, acting as an essential micronutrient for Photosystem II photoassembly and photosynthetic oxygen evolution. Nickel and cobalt play indirect roles, mainly as cofactors of the nickel/cobalt transporter-permease NiCo-PIC1, which transports ferrous iron through the inner membrane of the chloroplast, and cobalt is a chaperone of copper in the copper/zinc superoxide dismutase.

The authors also stress that elements work as teams within protein complexes, and that these team relationships are equally essential. Iron and sulfur partner in a Rieske protein. Calcium and manganese partner in the Mn4CaO5 cluster and again in lectins. Cobalt, zinc and copper cooperate in the copper/zinc superoxide dismutase. Iron, nickel and cobalt cooperate in NiCo-PIC1. Metal transporter families, including ABC, CAX, CCX, CDF/MTP, ECA, HMA, NRAMP, OPT, VIT and ZIP, enable the uptake and movement of these nutrients, and transporters coordinate the interplay of compounds, metals and metalloids that regulate the acquisition, distribution and efficient utilization of essential plant nutrients. Close to a third of all known enzymes are associated with the metal elements calcium, magnesium, iron, manganese, zinc, copper, nickel and cobalt, and these elements are required for the activity of their respective metalloenzymes. The activity of cobalt in chloroplast functions, the authors note, supports its classification as an essential element, and like nickel its optimal foliar dose may be in the nanomolar range.

Signaling and crosstalk emerge as the connective tissue that directs the metabolic pathways of photosynthates such as sugars. Recent work summarized in the review shows that signaling between nitrogen, phosphorus, sulfur, zinc and iron may involve complex crosstalk processes in response to nutrient deficiency, and that dynamic nutrient signaling networks connect sugar, nitrate and phosphate in controlling molecular pathways. Carbon and nitrogen assimilation are integrated processes, and co-application of elevated carbon dioxide with nitrogen promotes the synthesis of nitrogenous products key to growth, while molybdenum plays key roles in nitrogen assimilation. Several enzymes in the path of carbon are activated by the reduction of disulfide bonds on conversion, in light, of ferredoxin reduced in Photosystem I to a thiol signal, meaning that the light and carbon reactions employ sulfur to transmit signals in the process of photosynthesis. Deficiencies of secondary fertilizers such as calcium, magnesium and sulfur in lateritic and leached acid soils are growing concerns for farm production precisely because these minerals are vital to photosynthesis. Where a deficiency of any element is diagnosed, supplementation by foliar applications is recommended, and because the light reactions of photosynthesis are measured in picoseconds, nutrients cannot be drawn up from roots in the soil to the shoot with such rapidity, making foliar placement at the site of the photosynthetic processes potentially important.

The review closes with a forward-looking argument for agriculture and for the transfer of photosynthesis-related technologies to the field. When treating crops with plant growth regulators, nitrogen input plays integral roles in carbon partitioning, and co-application of essential plant nutrient elements with regulators such as methyl-alpha-D-mannopyranoside, a plant growth regulator for photosynthesis, were found to enhance yields as compared to nutrient controls, with a recognized role for manganese and calcium in the lectin cycle. Lectins have roles in the carbon reactions of photosynthesis, the sugar code and cell signaling, and ongoing studies of the plant lectome may lead the field toward glycomimetics, molecules that emulate the structure and function of natural glycans, which the authors suggest could improve the efficiency of photosynthesis. The authors recommend further investigations, especially for cultivated plants, by means of biocuration and genetic tools including transcriptomics, metabolomics, proteomics, genomics, epigenomics, ionomics and lipidomics, seeking information about the specificity of metalloenzymes to corresponding organelles such as chloroplasts, peroxisomes and vacuoles. They also point to silicon as a beneficial mineral whose interactions with photorespiration and with essential and beneficial elements may indicate a critical role. For now, the message is clear: photosynthesis depends on the presence of essential mineral elements at their sites of action, for the most part in the leaves and green stems of crop plants, and securing their sufficiency is inseparable from securing the energy transformation on which all green plants, and the food systems built upon them, ultimately rely.

Subject of Research: The roles of essential nutrient elements in the light and carbon reactions of photosynthesis

Article Title: The essential nutrient elements in photosynthesis

Article References: Shevela, D., & Nonomura, A. (2026). The essential nutrient elements in photosynthesis. Frontiers in Photobiology, 4, Article 1817712. https://doi.org/10.3389/fphbi.2026.1817712

Image Credits: AI Generated

DOI: 10.3389/fphbi.2026.1817712

Keywords: photosynthesis, essential nutrients, mineral nutrition, chloroplast, Photosystem II, Photosystem I, macronutrients, micronutrients, metalloproteins, electron transport, crop productivity, plant signaling

The study, published in the journal Discover Soil, examined Guanoboost, a commercially available organic fertilizer built around seabird and bat guano and blended with biochar, kraal manure, lime, molasses, and gypsum. Guano has long been prized for its exceptional concentrations of nitrogen, phosphorus, and potassium, and the manufacturer positions the product as an environmentally sustainable alternative to synthetic fertilizers. Yet farmers have reported inconsistent performance across different fields, and the researchers wanted to know why. Their hypothesis was that the answer lies not in the fertilizer itself but in the starting condition of the soil it is applied to.

To test this, the team collected topsoil from three contrasting sites in South Africa’s Eastern Cape: a Katspruit Gleysol from the University of Fort Hare Research Farm, a Hutton Humic Ferralsol from Hogsback, and a Klapmuts Haplic Cambisol from Upper Gqumashe. Based on pH, nutrient levels, and heavy metal concentrations, the soils were classified as slightly, moderately, or severely degraded respectively. Each soil was then mixed with Guanoboost at five rates: an untreated control, 200, 400, 600, and 800 kilograms per hectare, spanning half to double the manufacturer’s recommended field rate for potatoes. The mixtures were placed in sealed containers, moistened to 70 percent of water-holding capacity, and incubated at around 30 degrees Celsius for 84 days, with destructive sampling at 21-day intervals.

The experimental design was deliberately rigorous. With five fertilizer rates, three soil types, and four sampling periods, replicated three times, the study generated 180 experimental units arranged in a randomized complete block design. The researchers measured soil pH, macronutrients including nitrogen, phosphorus, potassium, calcium, magnesium, and sodium, micronutrients including iron, manganese, zinc, and copper, and the heavy metals aluminium and chromium. Nutrient extraction involved microwave digestion with nitric acid and hydrogen peroxide, followed by analysis with inductively coupled plasma mass spectrometry, while nitrate and phosphate were quantified after water extraction and centrifugation. Statistical analysis used three-way analysis of variance with Tukey’s honestly significant difference test for mean separation.

The first striking result was what did not matter. The three-way interaction between fertilizer rate, soil degradation level, and incubation time was not statistically significant for any measured parameter, meaning the combined effect of all three factors did not shape soil chemistry in any meaningful way. Instead, the main effects of soil degradation level and incubation time dominated, both highly significant across nearly every variable. Fertilizer rate played a comparatively minor role, appearing as a significant interaction only for calcium and, in a separate analysis, for iron. This finding challenges the intuitive assumption that simply applying more organic fertilizer will proportionally improve soil fertility.

Soil degradation level proved to be the strongest predictor of macronutrient availability. The moderately degraded soil consistently showed the highest concentrations of nitrogen at 7.52 milligrams per kilogram, phosphorus at 1.54, potassium at 8.62, calcium at 28.37, and sodium at 2.81. The slightly degraded soil, despite its name, recorded the lowest levels of all macronutrients, particularly potassium at 5.53 and calcium at 13.09, a pattern the researchers attribute to the nutrient-leaching effect of acidity. The severely degraded soil fell in between, comparable to the moderately degraded soil for calcium but lower for nitrogen and phosphorus, likely because low soil carbon limited its capacity to retain nutrients.

Temporal dynamics added another layer of insight. Across all soils, most macronutrients peaked around day 63 of incubation, a pattern consistent with microbial decomposition of the organic amendment. Calcium, which ranged between 15 and 30 milligrams per kilogram, declined initially between days 21 and 42 before rising at day 63, suggesting dissolution and re-adsorption cycles as the amendment broke down. Nitrogen and potassium showed their steepest increases between days 42 and 63, pointing to this window as the period of most active microbial mineralization. Phosphorus and sodium remained relatively stable throughout, implying limited mobilization or strong adsorption to soil particles. The researchers interpret this as a timed biological rhythm rather than a linear release curve, one that could theoretically be synchronized with crop nutrient demand.

The response to fertilizer rate followed a non-linear pattern that reinforces the importance of moderation. Nitrogen concentrations increased with amendment rate up to 600 kilograms per hectare, reaching a peak of 7.85 milligrams per kilogram, then declined at the highest rate of 800 kilograms per hectare. This diminishing-returns curve suggests that beyond a certain threshold, microbial immobilization or leaching reduces the efficiency of nutrient mineralization. The finding aligns with previous research showing that excessive organic amendment rates can actually reduce nutrient availability compared to moderate applications, and it positions the 600-kilogram rate as the sweet spot for maximizing nitrogen accumulation while minimizing losses.

Micronutrient behavior revealed the powerful influence of soil chemistry on metal solubility. The slightly degraded soil, with its acidic pH, accumulated the highest iron at 407.09 milligrams per kilogram and zinc at 365.67, consistent with enhanced metal solubility under low-pH conditions. The severely degraded soil recorded the highest manganese at 6836.80 milligrams per kilogram but the lowest copper and zinc, likely reflecting redox-driven dissolution of manganese oxides in carbon-deficient environments. The moderately degraded soil maintained the most balanced micronutrient profile. Correlation analysis confirmed these relationships, showing a strong negative association between iron and pH, with a coefficient of negative 0.64, demonstrating that iron availability is directly governed by acidity.

Perhaps the most consequential finding concerned heavy metals. Aluminium and chromium concentrations were highest in the slightly degraded soil, at 460.87 and 700.33 milligrams per kilogram respectively, and decreased progressively as soil pH increased. Aluminium in the acidic soil fluctuated from 437.41 at day 21 to over 500 by day 84, while chromium rose from 656 to approximately 700 in early stages and exceeded 1000 by the end of incubation. In contrast, the moderately and severely degraded soils, with their higher pH, maintained substantially lower metal concentrations throughout. This inverse relationship between pH and metal mobility suggests that the lime component of Guanoboost, or the pH-buffering effect of organic matter decomposition, may actively reduce the bioavailability of toxic metals, offering a pathway to rehabilitate acidic and contaminated soils.

The authors conclude that soil-specific characteristics, rather than uniform application rates, should guide organic amendment strategies. Moderately and severely degraded soils benefited most from moderate application rates, while the slightly degraded soil may require prior pH correction before amendment can deliver its full benefit. They recommend aligning fertilizer application with the period of maximum microbial activity, integrating Guanoboost into soil health rehabilitation programs for its pH-stabilizing and metal-immobilizing properties, and promoting bio-based fertilizers through extension and policy frameworks. Future research, they note, should focus on long-term field validation and microbial enzyme dynamics to fully unravel the biochemical mechanisms underlying nutrient release and heavy metal stabilization. For now, the message is clear: the soil you start with matters as much as the fertilizer you add.

Subject of Research: Effects of guano-based organic fertilizer application rates on nutrient availability and heavy metal dynamics in soils with different degradation levels

Article Title: Influence of organic fertilizer rates on nutrients and heavy metals dynamics in degraded soils

Article References: Manyaku, A., Chiduza, C., Dzvene, A. R., Mthunzi, F., & Witbooi, H. (2026). Influence of organic fertilizer rates on nutrients and heavy metals dynamics in degraded soils. Discover Soil, 3(1), Article 189. https://doi.org/10.1007/s44378-026-00319-5

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00319-5

Keywords: soil degradation, organic fertilizer, guano, soil pH, nutrient mineralization, heavy metals, aluminium toxicity, chromium, soil incubation, soil fertility, micronutrients, sustainable agriculture

The black monkey orange is a deciduous tree of the Loganiaceae family that thrives across tropical and subtropical Africa, including South Africa, Lesotho, Zimbabwe, and Eswatini. Growing five to eight meters tall, usually with a single stem and a spreading, uneven canopy, it carries pale grey bark marked with white patches and leathery, hairy green leaves. Unlike domesticated crops, it flourishes precisely where agriculture struggles most, in hot and relatively dry conditions, making it one of the most resilient indigenous fruit species in the region. In Bushbuckridge Local Municipality, where the review is centered, locals call the tree and its fruit Makwakwa in Xitsonga, and in southern Mozambique the same species goes by the name Macuácua, a striking linguistic echo across the border.

The review, written by Philix Mnisi, systematically searched databases including Google Scholar, Science Direct, Scopus, and Web of Science between November 2025 and August 2026, screening 112 articles down to 72 relevant studies. From this body of literature the author reconstructed the complete indigenous processing cycle for Nkwakwa, a name that refers both to the final powdered product and, locally, to the tree itself. The cycle begins with gathering ripened fruit between August and December, a season when cultivated foods are often scarce across Southern Africa. The fruit itself is a large, smooth, nearly spherical berry, roughly 8 to 10 centimeters in diameter, that shifts from green or blue-green to orange-yellow as it matures.

Cracking that fruit is no small feat, because the shell is extremely hard and woody. Communities smash it open using hard objects, and the review notes a traditional practice missing from the formal literature: two fruits are sometimes cracked against each other. Once the shell is broken, the seeds are retrieved by hand and the pulp is separated. The seeds and their pulp are then sun-dried, often spread on corrugated iron sheets, in a technique that is a cornerstone of indigenous knowledge systems across Africa. Sun drying reduces microbial viability and can preserve monkey orange pulp for anywhere from two months to five years, according to previous research. It is also remarkably sustainable, relying on solar thermal energy rather than electricity or fuel, though it carries drawbacks including potential contamination and losses of heat-sensitive bioactive compounds such as carotenes, vitamin C, and phenolics.

After drying, the kernels are separated from the dried seed coat, which is then crushed or ground in a traditional hardwood mortar into the fine powder known as Nkwakwa in South Africa and Nfuma in Mozambique. The flour can be eaten on its own or mixed with honey or sugar to soften its natural bitterness, and some fruits are sweet enough to need nothing at all. Crucially, the powder keeps for long periods without spoiling, a property that transforms a highly seasonal wild fruit into a year-round food reserve. That longevity is exactly what makes Nkwakwa valuable during shortages and droughts, when rural communities historically have turned to indigenous fruits as survival foods.

The nutritional analysis assembled in the review is where the story becomes genuinely compelling. Studies of the flour report fat content ranging from about 26 to 46 percent, fiber exceeding 6 percent with some measures reaching 53 grams, carbohydrates around 10 percent, vitamin E at 6.7 to 8.0 milligrams per 100 grams, and carotenes at 2.2 to 2.6 milligrams per 100 grams. The seed coat itself carries roughly 42 percent oil on a dry weight basis. Among macronutrients, potassium levels range from 594 to 1,660 milligrams per 100 grams, meaning a single serving contributes meaningfully toward the World Health Organization’s recommended daily intake of 3,510 milligrams, which supports blood pressure control, muscle function, and nerve transmission. Sodium content is refreshingly low at 16 to 51 milligrams per 100 grams, a tiny fraction of the recommended ceiling, while magnesium hovers near 80 milligrams per 100 grams, contributing nearly a fifth of the adult requirement.

The micronutrient profile is equally notable. Manganese reaches up to 9.86 milligrams per 100 grams, essentially meeting the full average recommended daily intake of about 10 milligrams, which supports bone health, enzyme activity, and antioxidant defense. Iron content ranges from 3.4 to 15.8 milligrams per 100 grams, approaching the upper population reference intake, a significant finding in a region where iron deficiency anemia remains widespread. Zinc and copper are present at 0.1 to 1.36 and 0.40 to 0.72 milligrams per 100 grams respectively, both essential for immune function, enzyme systems, and red blood cell formation. The fruit also contains vitamins A and C, key biochemical components that protect the immune system, eyesight, nervous system, and cardiovascular health.

Perhaps the most surprising detail concerns the fruit’s oil. The Macuácua oil pressed from dried pulp flour has a higher oleic acid content than baobab, watermelon seed, or mongongo oils, and rivals marula oil, whose oleic acid content reaches 70 to 78 percent. Oleic acid is the same monounsaturated fat that dominates olive and canola oils, and accumulating evidence suggests it helps regulate body weight and may protect against obesity and related metabolic problems. Combined with the powder’s exceptional fiber content, which exceeds adequate intake recommendations for both women and men, the review argues that regular consumption of Nkwakwa could help reduce the long-term risk of cardiovascular disease, type 2 diabetes, and colorectal cancer, while improving digestive health.

Beyond the numbers, the review situates Nkwakwa within a global context. It connects the product to the United Nations Sustainable Development Goal of Zero Hunger, noting that Southern Africa holds a significant supply of edible indigenous fruit species capable of addressing food and nutritional shortages. Previous studies have found that Nkwakwa products offer health benefits for children and immune-compromised people, with regular consumption apparently increasing weight and disease resistance. Crude extracts of the seed coat and pulp have even shown antioxidant and antidiabetic potential in laboratory studies, hinting at future nutraceutical applications for diabetes management.

The review also sounds a note of caution. Many indigenous fruits remain underutilized, and of 82 documented edible indigenous fruit species in one cited study, only 22 had been recorded as traditionally processed or preserved, suggesting dozens of species with untapped food potential. Domestic processing and preservation methods need upgrading to reliably extend availability beyond the August-to-December harvest window, and further processing is required to ensure the safety of seed-derived products for human consumption. Still, the author’s conclusion is clear: the black monkey orange and its value-added products deserve preservation, promotion, and wider consumption. In a warming world where drought-tolerant, nutrient-dense foods are increasingly precious, this ancient powder from a forgotten tree may be one of the most quietly important foods Southern Africa has.

Subject of Research: Nutritional value and traditional processing of the indigenous African fruit product Nkwakwa from Strychnos madagascariensis

Article Title: A review: indigenously processed dried powdered food product “Nkwakwa” and the nutrients of Strychnos madagascariensis from Bushbuckridge Local Municipality, Mpumalanga, South Africa

Article References: Philix, M. (2026). A review: indigenously processed dried powdered food product “Nkwakwa” and the nutrients of Strychnos madagascariensis from Bushbuckridge Local Municipality, Mpumalanga, South Africa. Frontiers in Sustainable Food Systems, 10, Article 1965994. https://doi.org/10.3389/fsufs.2026.1965994

Image Credits: AI Generated

DOI: 10.3389/fsufs.2026.1965994

Keywords: black monkey orange, Strychnos madagascariensis, Nkwakwa, indigenous fruit species, food security, nutrition, sun drying, micronutrients, oleic acid, dietary fiber, South Africa, sustainable food systems

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 research, conducted by a team at the Federal University of Uberlândia and published in Environmental Monitoring and Assessment, set out to chart the spatial distribution of entomopathogenic nematodes across five tropical cropping systems and to probe whether soil chemistry might explain where the worms flourish and where they fail. Working on two farms in the municipality of Monte Carmelo, in the Triângulo Mineiro region of Minas Gerais, the researchers collected 82 soil samples from avocado, atemoya, passion fruit, pitaya, and coffee plantations between January and May 2024. The sites sit at roughly 1,000 meters above sea level on Dystrophic Red Latosol soils under a tropical savanna climate, with rainfall concentrated in the summer months.

Detecting the nematodes required a technique that is elegantly simple in concept. At each sampling point, the team collected about 400 grams of soil from the 5 to 15 centimeter layer, discarding the surface to avoid contamination. Back at the Agricultural Entomology Laboratory, each sample was placed in a container with six mid-instar larvae of the mealworm Tenebrio molitor, a classic bait insect. If entomopathogenic nematodes were present in the soil, their infective juveniles would locate the larvae, invade them, and kill them within five to seven days. Dead larvae showing signs of infection were sterilized, and the emerging nematodes were harvested using White traps, a method dating back nearly a century. To satisfy Koch’s postulates, the researchers re-infected healthy larvae with the collected nematodes and confirmed the infections, ensuring that what they had isolated was genuinely pathogenic.

The chemical side of the investigation was equally systematic. Soil analyses measured calcium, magnesium, potassium, manganese, sulfur, boron, iron, copper, and zinc at each sampling point. The team then turned to geospatial tools to make these numbers visible. Using ArcGIS software, they generated heatmaps of nematode presence through kernel density estimation, a technique that smooths scattered presence points into a continuous surface of relative density. For the soil attributes, they built interpolated surfaces with the Topo to Raster method, chosen for its ability to produce hydrologically consistent surfaces from irregularly distributed field data. Contour lines from the chemical maps were overlaid on the nematode density maps, creating correlation maps that allowed the researchers to visually infer where nematode hotspots coincided with particular nutrient concentrations.

The statistical results were striking. Simple linear regression revealed significant associations between nematode presence and six soil attributes: potassium, sulfur, boron, iron, copper, and zinc. Boron showed the strongest statistical relationship, with a correlation coefficient of 0.78 and an explanatory power of nearly 60 percent, followed by potassium at 0.68 and iron at 0.67. Sulfur showed a moderate association, while zinc and copper were weaker but still significant. Calcium, magnesium, and manganese, by contrast, showed no meaningful relationship with nematode occurrence. Yet the spatial analysis told a more nuanced story. When the researchers examined the correlation maps, only potassium and iron displayed consistent spatial patterns across both farms, with nematodes more frequently detected in areas where potassium exceeded 0.23 centimoles per cubic decimeter and in zones with elevated iron. Copper showed the opposite pattern, with nematode occurrence tending to decrease where copper concentrations were high, particularly at the Pastão farm.

Why would these particular elements matter? The researchers propose that the connections are indirect, operating through the soil’s microbial communities and the rhizosphere, the bustling zone around plant roots. Potassium is known to enhance root development and alter the pattern of root exudates, the sugars and compounds that plants release into the soil, which in turn stimulates microbial activity and may create conditions favorable for nematode survival and host-seeking. Iron plays a central role in microbial competition, particularly through siderophores, iron-chelating molecules that microbes produce to scavenge this essential element. Recent research has even shown that bacterivorous nematodes can use microbial siderophores as cues in predator-prey interactions. Because entomopathogenic nematodes depend entirely on their symbiotic bacteria, Xenorhabdus and Photorhabdus, to kill hosts and make the environment suitable for reproduction, shifts in microbial community dynamics could ripple directly into nematode performance.

Copper’s negative association is equally telling from an ecological standpoint. Elevated copper concentrations are known to reshape soil microbial communities, reducing their diversity and functional activity. Since the nematodes’ success hinges on their bacterial partners, copper-induced disruption of the microbial community may indirectly limit nematode survival and infectivity. This finding carries practical weight, because copper accumulates in agricultural soils through repeated fungicide applications, and the study suggests that such accumulation could undermine the very biological control agents farmers hope to encourage. Zinc, meanwhile, behaved inconsistently between the two farms, associated with higher nematode presence at one site and intermediate levels at the other, preventing the identification of any clear threshold. Boron, despite its strong statistical association, showed no coherent spatial pattern at all, a reminder that statistical correlation and spatial structure do not always align.

Principal Component Analysis added a crucial multivariate dimension to the picture. The first two principal components together explained 86.4 percent of the total variance in the soil chemistry data, with the first component alone accounting for 66 percent. This component separated soils rich in calcium, magnesium, copper, manganese, zinc, boron, and base saturation from soils characterized by higher aluminum, sulfur, iron, and potassium. The analysis confirmed that soil chemical attributes are strongly interrelated, meaning that nematode occurrence is associated with multivariate soil conditions rather than with any isolated nutrient. In other words, the significant relationships observed for potassium and iron should be understood within a broader web of interacting soil properties, not as simple cause-and-effect levers that a farmer could pull independently.

The authors are careful to emphasize the limits of their conclusions. This was an observational survey conducted under commercial farming conditions, so the spatial associations identified do not establish causal mechanisms. Crop management practices varied across the study period, including applications of mineral fertilizers, biological insecticides, biological nematicides, and microbiological fungicides, and factors such as soil moisture, texture, pH, and microbial community composition were not fully controlled. The study also captured a single sampling period in each crop system, so seasonal variation and long-term changes in soil properties remain unexplored. The absence of aluminum measurements for one of the study areas further limited the assessment of acidity-related toxicity, which previous research suggests can reduce nematode survival through increased aluminum solubility. The lower sampling density in the large coffee plantation may also have masked fine-scale spatial heterogeneity.

Even with these caveats, the study points toward a future in which biological control becomes a precision practice rather than a gamble. By combining insect-baiting surveys with kernel density mapping, interpolation, regression, and multivariate statistics, the researchers demonstrated a framework for identifying hotspots of natural pest suppression and linking them to environmental conditions. The authors suggest that future work should integrate controlled experiments with repeated temporal sampling, larger datasets, and additional physical and biological soil variables, potentially incorporating machine learning algorithms and spatial predictive models. If those efforts succeed, agronomic thresholds established for crop nutrition may one day be complemented by ecological thresholds for beneficial soil organisms, allowing farmers to manage their soils not just for what grows above ground, but for the microscopic allies working below it. In tropical agroecosystems, where environmental heterogeneity is high and chemical inputs carry heavy costs, that kind of map could prove invaluable.

Subject of Research: Spatial distribution of entomopathogenic nematodes and its association with soil chemical attributes in tropical agroecosystems

Article Title: Spatial distribution of entomopathogenic nematodes and their relationship with soil chemical attributes in tropical agroecosystems

Article References: Souza, N., Andaló, V., Indjai, L. R., Martins, G. D., de Faria, L. S., & de Assis, G. A. (2026). Spatial distribution of entomopathogenic nematodes and their relationship with soil chemical attributes in tropical agroecosystems. Environmental Monitoring and Assessment, 198(9), Article 1037. https://doi.org/10.1007/s10661-026-15875-0

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15875-0

Keywords: entomopathogenic nematodes, biological control, soil chemistry, geospatial analysis, tropical agriculture, micronutrients, soil microbiome, rhizosphere, integrated pest management, kernel density estimation, principal component analysis, Brazil

The experiment was designed around a simple but urgent question: how will the two dominant drivers of atmospheric change, rising CO2 and shifting UV-B radiation, affect the growth and physiology of plants that are increasingly promoted as climate-smart crops? Moringa oleifera, the well-known drumstick tree cultivated across South Asia and Africa for its nutritious leaves, and Moringa peregrina, a hardier, drought-adapted relative native to the Arabian Peninsula and the Horn of Africa, were both raised under controlled environmental treatments. Open-top chambers allowed the plants to experience near-natural field conditions of light, temperature, and airflow while the researchers precisely manipulated the concentrations of gases and the dose of UV-B reaching the foliage.

Elevated CO2 produced a clear growth dividend, but only for one of the two species. Moringa oleifera grown under enriched CO2 grew taller than its Arabian cousin, suggesting that the drumstick tree is better positioned to exploit the carbon fertilization effect, the phenomenon by which higher atmospheric CO2 accelerates photosynthesis and biomass accumulation in many C3 plants. Decades of free-air CO2 enrichment experiments worldwide have documented this effect across a wide range of crops, though its magnitude varies enormously between species and growing conditions. The new findings indicate that Moringa oleifera sits on the responsive end of that spectrum, while Moringa peregrina, despite its reputation for toughness in harsh environments, did not translate the extra carbon into comparable height gains.

UV-B radiation told the opposite story. When the plants were exposed to enhanced ultraviolet-B, the lowest plant heights were recorded in both species, confirming that this high-energy component of sunlight remains a potent growth suppressant even as background levels shift with stratospheric ozone dynamics. UV-B photons damage photosynthetic machinery, trigger the production of reactive oxygen species, and force plants to divert energy and carbon into protective compounds such as flavonoids and other phenolics rather than into new tissue. For both moringas, the cost of that defense was measurable in stature, a reminder that the benefits of carbon fertilization can be eroded when plants simultaneously face radiation stress.

The photosynthetic pigments told a consistent tale. Chlorophyll a, chlorophyll b, and carotenoid content were substantially higher in CO2-enriched Moringa oleifera than in Moringa peregrina under the same treatment, indicating a more vigorous light-harvesting apparatus and a greater capacity to convert the additional carbon into chemical energy. Carotenoids matter here beyond photosynthesis: they participate in photoprotection, quenching excess excitation energy before it generates damaging radicals. Yet UV-B exposure significantly reduced photosynthetic pigments in both species, consistent with its well-documented ability to degrade chlorophyll and impair the thylakoid membranes where the light reactions of photosynthesis take place. The pigment data thus reinforce the growth data, painting a picture in which CO2 lifts one species up while UV-B drags both down.

Perhaps the most surprising results emerged from the nutrient analysis. Under elevated CO2, Moringa oleifera accumulated significantly higher concentrations of nitrogen, magnesium, calcium, and boron than Moringa peregrina. Nitrogen is the backbone of chlorophyll and photosynthetic enzymes, magnesium sits at the center of every chlorophyll molecule, and calcium structures cell walls and acts as a ubiquitous intracellular signal, so higher levels of these elements underpin the superior growth and pigment performance observed in the drumstick tree. Boron, required in small amounts for cell wall cross-linking and pollen tube growth, rounds out a profile of enhanced mineral nutrition in the species that grew best.

Moringa peregrina, however, was not simply outperformed. The Arabian species concentrated greater amounts of potassium, iron, manganese, copper, zinc, and sulfur under elevated CO2. Each of these elements plays a distinct role in stress physiology: potassium regulates stomatal opening and cellular water balance, iron and copper are cofactors in electron transport chains and antioxidant enzymes, manganese powers the water-splitting reaction of photosystem II and supports antioxidant defenses, zinc stabilizes proteins and membranes, and sulfur feeds the synthesis of glutathione and other sulfur-containing protectants. A leaf enriched in this suite of micronutrients is, in effect, chemically armored, suggesting that Moringa peregrina invests its mineral resources in resilience machinery rather than in rapid extension growth.

This divergence in nutrient allocation strategies carries practical weight. Moringa oleifera has been championed as a versatile climate-smart plant for nutritional security in semi-arid regions, prized for protein-rich leaves and fast growth. The new data support that reputation under future CO2 levels, at least when UV-B is not overwhelming. But Moringa peregrina, which grows wild in some of the driest habitats on the Arabian Peninsula and is valued locally for its oil-rich seeds, appears to build a different kind of advantage, one based on micronutrient-dense tissue and stress-hardy biochemistry. For breeders and land managers, the two species may therefore serve complementary roles: oleifera for productivity, peregrina for persistence and possibly for nutritional profiles enriched in iron, zinc, and other elements often lacking in human diets.

The study also contributes to a broader scientific debate about whether the greening effect of rising CO2 will compensate for the stresses that accompany it. Elevated CO2 generally improves water-use efficiency and stimulates photosynthesis in C3 plants, but those gains can be offset by heat, drought, ozone, and radiation stress, and they often come at the price of lower tissue nutrient concentrations. By testing CO2 and UV-B together in realistic field-adjacent conditions, the UAE team has added a rare data point from a hyper-arid environment, where the interaction between carbon enrichment and solar radiation stress may differ from temperate agricultural systems. The finding that one moringa species thrives while the other retools its chemistry under the same future atmosphere underscores a central lesson of modern plant science: climate resilience is not a single trait but a portfolio, and different species hold different shares.

For now, the message for the Arabian Peninsula and similar regions is one of cautious optimism. The drumstick tree looks set to grow taller and photosynthesize harder in a carbon-rich world, provided ultraviolet-B stress remains within tolerable bounds, while its native relative offers a hardier, micronutrient-rich alternative for the harshest sites. As the researchers note, understanding these combined effects is essential for predicting how crop systems and ecosystems will fare as the climate changes. The moringa experiment suggests that the winners of the next century will not simply be the plants that grow fastest, but those that can balance growth against defense, and that balance is written, element by element, in their leaves.

Subject of Research: Growth and physiological responses of two Moringa species to elevated CO2 and UV-B radiation

Article Title: Evaluating growth and physiological responses of Moringa peregrina and Moringa oleifera to elevated CO₂ and UV-B radiation in open-top chambers for climate resilience

Article References: Alshehhi, O. M. S., Hayat, F., Kandhan, K., AL-Zayadneh, W., Sheteiwy, M. S., & Alyafei, M. (2026). Evaluating growth and physiological responses of Moringa peregrina and Moringa oleifera to elevated CO₂ and UV-B radiation in open-top chambers for climate resilience. The Science of Nature, 113(6), Article 131. https://doi.org/10.1007/s00114-025-02041-8

Image Credits: AI Generated

DOI: 10.1007/s00114-025-02041-8

Keywords: Moringa oleifera, Moringa peregrina, elevated CO2, UV-B radiation, open-top chambers, photosynthetic pigments, plant nutrition, climate resilience, environmental stress, arid agriculture, chlorophyll, micronutrients

Selenium is an essential micronutrient that the human body incorporates into a family of proteins known as selenoproteins. These proteins perform a remarkable range of biochemical duties, including antioxidant defense, thyroid hormone metabolism, and immune regulation. The brain is particularly dependent on this system because neural tissue consumes a disproportionate share of the body’s oxygen and generates a steady stream of reactive oxygen species as a byproduct of its relentless metabolic activity. When selenium is scarce, the antioxidant capacity of developing neurons may be compromised at precisely the moment when the brain is wiring itself at its most furious pace. Deficiency has also been linked in animal studies to alterations in neurotransmitter systems, including dopaminergic and serotonergic pathways, which are central to attention regulation and impulse control. This biological plausibility is what motivated the research team to ask whether a mother’s selenium status during pregnancy leaves a measurable trace in her child’s behavior years later.

The study drew on a well-established cohort in Bhaktapur, a city in the Kathmandu Valley where the research group has conducted nutrition studies for more than a decade. In total, 720 mother-infant dyads were enrolled, and maternal plasma selenium concentrations were measured in blood samples taken early in pregnancy. This timing matters. The first trimester and early second trimester are periods of rapid neural tube formation, neuronal proliferation, and the beginnings of synaptic architecture, so any nutritional insult during this window could theoretically have outsized consequences. The researchers then waited, quite literally, for the children to grow. When the children reached four years of age, their mental health was assessed using a parent-reported questionnaire called the Strengths and Difficulties Questionnaire, or SDQ, in its Nepalese version.

The SDQ is one of the most widely used brief behavioral screening instruments in the world. It asks parents to rate their child on a series of attributes that cluster into five subscales: emotional symptoms, conduct problems, hyperactivity-inattention, peer relationship problems, and prosocial behavior. Because the questionnaire had not previously been validated in this specific Nepalese preschool population, the team took the methodologically important step of testing whether the original five-factor structure actually held up in their data. Using confirmatory factor analysis, a statistical technique that evaluates how well observed responses map onto hypothesized underlying dimensions, they found that the five-factor model fit the data well after some modifications. The comparative fit index reached 0.967, comfortably above conventional thresholds, while the root mean square error of approximation was 0.059, indicating acceptable approximation error. In practical terms, this means the Nepalese version of the parent-rated SDQ can be considered a psychometrically sound tool for assessing preschool mental health in this setting, a contribution that will benefit future research in the region regardless of what the selenium analysis showed.

The average maternal plasma selenium concentration in the cohort was 74.7 micrograms per liter, with a standard deviation of 10.2 micrograms per liter. This figure sits in an interesting zone. It is not low enough to constitute overt deficiency by most clinical standards, but it is well below the concentrations typically observed in selenium-replete populations in North America and parts of Europe, where means can exceed 100 micrograms per liter. Nepal’s soil is known to be variable in selenium content, and the predominantly cereal-based local diet does not necessarily compensate for that variability. The researchers therefore had genuine reason to suspect that a meaningful fraction of the pregnant women in the cohort might be experiencing suboptimal selenium status during a critical developmental window.

To analyze the relationship between prenatal selenium and child behavior, the team used generalized linear models, examining maternal plasma selenium both as a continuous variable and in categorized forms, including tertiles that divided the sample into thirds of exposure. The children’s SDQ subscale scores served as the outcomes. The headline finding emerged from the tertile analysis: children whose mothers fell in the lowest selenium tertile during pregnancy had significantly higher hyperactivity-inattention scores at age four than children whose mothers were in the middle tertile. The adjusted regression coefficient was 0.329, with a 95 percent confidence interval running from 0.023 to 0.636, meaning the difference was statistically significant but modest in magnitude, and the confidence interval only narrowly excluded the null value of zero.

Crucially, however, the pattern did not behave the way a classic dose-response relationship would. If selenium deficiency were driving hyperactive behavior in a straightforward manner, one might expect the lowest tertile to differ from the middle tertile, and the middle tertile to differ from the highest, producing a graded gradient across the exposure distribution. Instead, the association appeared only when the lowest and middle tertiles were compared, and no corresponding difference emerged between the middle and highest groups. The analysis of selenium as a continuous variable likewise did not yield significant associations. The authors are appropriately cautious on this point, describing their evidence as limited and noting that the isolated finding lacks the clear exposure-response pattern that would strengthen a causal interpretation. It is possible that a threshold effect exists, in which only selenium status below a certain level matters, but it is equally possible that the result reflects chance, residual confounding, or the many comparisons inherent in examining multiple subscales across multiple exposure parameterizations.

Several other limitations deserve attention. The SDQ was completed by parents, which introduces the possibility of reporting bias, although the validation work strengthens confidence that the instrument measures coherent behavioral dimensions in this population. Plasma selenium reflects relatively recent intake and is influenced by the proteins that transport the element, notably selenoprotein P, so a single early-pregnancy measurement may not perfectly capture selenium status across the full gestational period. The Bhaktapur cohort, while valuable, is drawn from one urbanizing South Asian community, and its selenium distribution differs from that of populations where deficiency is rare, which limits generalizability in both directions. Confounding by overall nutritional quality is also a real concern, since women with low selenium may differ in other dietary and socioeconomic respects that independently influence child development, even though the models adjusted for available covariates.

Still, the study’s strengths are considerable. The prospective design, in which exposure was measured in pregnancy and outcome years later, removes much of the reverse-causation ambiguity that plagues cross-sectional nutrition research. The sample size of 720 dyads is respectable for a birth cohort study of this kind, and the dual contribution of a validated behavioral instrument and a novel exposure-outcome analysis makes the paper useful on two fronts. For selenium biology, the findings add a tentative data point to a small but growing literature linking maternal micronutrient status to child neurobehavioral outcomes, a field that has historically focused more heavily on iron, iodine, and folate. For public health in South Asia, the results raise the possibility that selenium, a mineral rarely included in prenatal supplementation programs, deserves closer scrutiny. The authors themselves conclude that confirmation in further studies is required, and that is the right note: one modest association, in one cohort, at one age, is a signal worth chasing rather than a conclusion worth announcing. Future work with repeated selenium measurements, biomarkers of selenium-dependent enzyme activity, and follow-up into school age will be needed to determine whether the trace element truly shapes the developing mind, or whether this finding dissolves under the weight of replication.

Subject of Research: The association between prenatal maternal selenium concentration and mental health outcomes in four-year-old children in a Nepalese mother-child cohort study.

Article Title: The association between prenatal maternal selenium concentration and mental health in early childhood, a mother-child cohort study

Article References: Ranjitkar, S., Kvestad, I., Chandyo, R. K., Bakken, K. S., Ulak, M., Strand, T. A., Huber, S., Averina, M., & Hysing, M. (2026). The association between prenatal maternal selenium concentration and mental health in early childhood, a mother-child cohort study. PLOS One, 21(10), e0360527. https://doi.org/10.1371/journal.pone.0360527

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360527

Keywords: selenium, prenatal nutrition, child mental health, hyperactivity, inattention, Nepal, birth cohort, Strengths and Difficulties Questionnaire, micronutrients, neurodevelopment, pregnancy, PLOS One