Brief rationale: Limited evidence exists on calcifediol's effect on lower extremity function in postmenopausal women with osteoporosis or osteopenia.

Calcifediol (20 µg/day) showed no greater benefit than vitamin D3 (3200 IU/day) or placebo. Significance of the paper: Findings do not support high-dose vitamin D3 or calcifediol for improving lower extremity function.

To test the effect of 20 µg/day of calcifediol compared with 3200 IU/day of vitamin D3 and placebo on lower extremity function in postmenopausal women with osteopenia or osteoporosis.

This is a 3-arm double-blind RCT among postmenopausal women aged 50-70 years with serum 25(OH)D < 30 ng/mL, and a DXA-based diagnosis of osteopenia or osteoporosis. Participants were randomized to receive either daily 20 µg calcifediol, daily 3200 IU vitamin D3, or placebo. The primary endpoint was a composite measure of lower extremity function, assessed at baseline, 3, and 6 months, including four tests: gait speed, knee flexor and extensor strength, and repeated sit-to-stand test. The primary endpoint was the probability of success (improvement or maintenance from baseline) in any of the eight tests, four tests at 3 months and four tests at 6 months.

The trial enrolled 152 women (mean age, 61.0 years; mean serum 25(OH)D level, 23.4 ng/mL), and all but one woman completed all follow-up visits. Baseline characteristics, including the four tests of lower extremity function, were balanced across the three groups. The adjusted probability of success in any of the eight tests was 53.6% (95% confidence interval 47%, 60%) with calcifediol, 55.5% (50%, 61%) with vitamin D3, and 61.4% (55%, 67%) with placebo, without significant differences between treatment groups.

Our findings do not support supplementation with daily calcifediol or equivalent high-dose daily vitamin D3 for improving or maintaining lower extremity function among younger postmenopausal women (age 50-70) with osteopenia or osteoporosis, who were pre-selected for vitamin D insufficiency or deficiency (25(OH)D < 30 ng/mL; baseline mean 25(OH)D 23.4 ng/mL).

Clinicaltrials.gov; NCT02527668; https://clinicaltrials.gov/ct2/show/NCT02527668.

Investigations into the association between serum 25-hydroxyvitamin D (25(OH)D) levels and the risk of age-related ocular diseases have yielded inconsistent results. Thus, we aimed to provide robust longitudinal evidence, identify optimal serum thresholds, and explore the underlying mechanisms.

We analyzed data of 322,953 participants from the UK Biobank. The serum 25(OH)D levels were assessed using chemiluminescent immunoassay. Outcomes were incidences of cataract, primary open-angle glaucoma (POAG), age-related macular degeneration (AMD), and diabetic retinopathy (DR). Hazard ratios and 95% confidence intervals were estimated using Cox proportional hazards models. Nonlinear relationships were explored using restricted cubic splines, and mediation analyses were performed to delineate potential mechanistic pathways.

Our findings revealed U-shaped associations for cataract and AMD, and L-shaped associations for DR (all P < 0.05), with an optimal threshold of approximately 50 nmol/L, while no association with POAG was observed. Below this threshold, each 10 nmol/L increase in serum 25(OH)D concentration was linked to a 3.5%, 4.2%, and 6.0% reduction in the risk of cataract, AMD, and DR, respectively (HR 0.965 [95% CI 0.951-0.980]; HR 0.958 [95% CI 0.921-0.997]; HR 0.940 [95% CI 0.894-0.989], respectively), while above 50 nmol/L, no significant protective effects were observed. Mediation analyses revealed that the low-grade inflammation score and triglyceride-glucose index may mediate the effects of serum 25(OH)D on cataract and DR.

This study identified 50 nmol/L as the optimal serum 25(OH)D threshold for reducing risks of cataract, AMD and DR, with no benefits beyond this level. The protective effects may be mediated through modulation of inflammation and glucolipid metabolism pathways. The threshold effects highlight the importance of targeted vitamin D supplementation under careful monitoring of serum levels to optimize ocular health outcomes.

Vitamin D acts as a pro-hormone with a wide range of beneficial effects. It is reported that vitamin D deficiency is a risk factor for COVID-19 severity in children. In the present study, we decided to assess 25 hydroxy (OH) vitamin D status in children with mild, moderate, or severe confirmed COVID-19 and also compare them with those of a healthy control group using existing data.

Relevant studies were extracted using online international databases including Scopus, Science Direct, PubMed, Web of Science, ProQuest, and Google Scholar search engine between Jan 2019 and 2024. The quality of all papers is determined by the NOS checklist. Heterogeneity between the results of primary studies was evaluated with the I-square index. Egger's test, funnel plot, and sensitivity analysis were applied. The statistical analysis was done using Stata version 17.

In 12 documents, the status of vitamin D was examined between case and control groups. By combining the results of these studies using random effect model, the standardized mean difference (SMD) vitamin D level in the COVID-19 children compared to the control group was estimated to be -0.88 (98% CI: -1.24, -0.51), which was statistically significant. In the present study, the odd ratio of vitamin D deficiency and vitamin D disorder (insufficiency and deficiency) in children with moderate COVID-19 compared to asymptomatic children with COVID-19 were estimated to be 3.58 (1.10, 11.63) and 2.52 (0.99, 6.41) respectively which was higher than in asymptomatic children with COVID-19. In addition, vitamin D deficiency and vitamin D disorder in children with moderate COVID-19 compared to the children with mild COVID-19 were estimated to be 2.12 (0.90, 4.98) and 1.82 (0.78, 4.22) respectively, which was higher than in children with mild COVID-19. Also, vitamin D deficiency and vitamin D disorder in children with mild COVID-19 compared to asymptomatic children with COVID-19 were estimated to be 2.02 (0.60, 6.78) and 1.64 (0.53, 5.07) respectively, which was higher than in asymptomatic children.

Combining the results of these studies, the effect size of the relationship between vitamin D and COVID-19 in children is significant. During the COVID-19 pandemic (except for the Omicron peak), children were less affected by the severity of COVID-19. The standardized mean difference (SMD) vitamin D level in children with COVID-19 was significantly 0.88 units lower than the control group. Also, the odds ratio of moderate COVID-19 in children with vitamin D deficiency was significantly 3.58 times higher than in asymptomatic children with COVID-19.

Background: Vitamin D plays a key role in bone metabolism and immune regulation. Populations with restricted sun exposure or limited dietary intake are particularly vulnerable to vitamin D deficiency. Orthodox Christian nuns represent a unique group in this regard, due to traditional clothing, limited outdoor activity, and prolonged religious fasting. However, few studies have compared them with lay individuals following similar dietary practices. Objective: This study aimed to investigate predictors of serum 25-hydroxyvitamin D [25(OH)D] concentrations in two female populations: Orthodox Christian nuns and women from the general population practicing intermittent (religious or non-religious) fasting. We also aimed to develop predictive models of vitamin D status for each group based on lifestyle and biochemical parameters. Methods: A total of 85 women (40 Orthodox nuns and 45 laywomen), aged 30-50 years, were enrolled. Serum 25(OH)D, parathyroid hormone (PTH), calcium levels, and anthropometric indices, including body mass index (BMI), total body fat, and visceral fat, were measured. Dietary calcium and vitamin D intake, as well as sun exposure, were assessed using validated questionnaires. Separate stepwise multiple regression models were constructed for each group to identify independent predictors of 25(OH)D concentrations. An additional combined model, including all participants, was also explored. Results: PTH was the most significant predictor, negatively correlating with 25(OH)D concentrations in both groups (p = 0.038), highlighting its regulatory role in vitamin D metabolism. When analyzed separately, the model for Orthodox nuns showed stronger explanatory power (adjusted R2 = 0.718; p = 0.013) compared with the control group (adjusted R2 = 0.362; p = 0.038), with PTH emerging as a key predictor in both. Conclusions: Distinct predictors of vitamin D status were identified in each group, reflecting the complex interplay between lifestyle and physiological factors. These findings suggest that targeted interventions, such as addressing PTH regulation in fasting populations or enhancing sun exposure in the general population, may be more effective in preventing vitamin D deficiency depending on the context.

Current vitamin D quantification methods do not account for 25-hydroxyl epimers, which can falsely increase concentrations and mask actual deficiencies. Previously, we developed an ultra-high performance liquid chromatography-tandem mass spectrometry method to measure 25(OH)D3, 3-epi-25(OH)D3 and 25(OH)D2; here, we extended this method to include 3-epi-25(OH)D2. Analytes were separated using a Shimadzu UPLC with a Kinetex F5 column (100 × 2.1 mm, 2.6 μm). The mobile phase contained 0.1% formic acid in methanol and water (70:30, v/v). The internal standard, deuterated 25(OH)D3 and analytes were extracted with hexane. Detection was performed by a mass spectrometer equipped with a triple quadrupole after prior electrospray ionization. It demonstrated sufficient precision and spike recovery within and between days, with a coefficient of variation ≤15% and an error of determination ≤18%. The method exhibited linearity in the 2-100-ng/mL concentration range. The limits of quantification and limits of detection were 2 and 1 ng/mL, respectively. Extraction recoveries ranged from 70.05% to 97.13%. The matrix effect, carryover and dilution integrity were evaluated and met the FDA acceptance criteria. The stability of all metabolites in plasma was confirmed after 3 h of storage at room temperature and after three cycles of freezing at -80°C and thawing. Applying the method to clinical samples showed a high 25-hydroxyl epimer derived from vitamin D.

The transintestinal epithelial absorption of vitamin D is intricately regulated by specific transport protein networks. Emerging evidence from molecular nutrition research reveals that certain dietary nutrients can enhance intestinal vitamin D absorption through targeted modulation of lipid transport pathways. Despite significant advancements in vitamin D delivery systems demonstrating excellent intestinal mucoadhesion and in vitro bioaccessibility, their clinical translation remains limited by suboptimal in vivo bioavailability. To address this critical challenge, we propose an innovative synergistic nutrient absorption strategy that establishes precise coordination among three key elements: dietary nutrient composition, transport protein regulation, and intestinal absorption optimization. This comprehensive review systematically examines: (1) The molecular mechanisms governing transintestinal vitamin D transport and physiological modulation of protein-mediated absorption pathways; (2) The regulatory effects of dietary components on vitamin D absorption efficiency through protein pathway modulation, proposing a novel "nutrient-transporter-vitamin D axis" strategy integrating cutting-edge carrier technologies; (3) Future perspectives for developing functionalized vitamin D delivery systems. The proposed paradigm shift, combining nutrient-mediated transport enhancement with advanced carrier engineering, represents a transformative approach to overcome current limitations in oral vitamin D delivery. This dual-modulation strategy synergistically improves intestinal absorption and systemic bioavailability through simultaneous optimization of biological transport mechanisms and pharmaceutical delivery parameters, offering new possibilities for precision nutrition interventions.

Given the global prevalence of vitamin D deficiency, this study examines the association between serum 25-hydroxyvitamin D (25(OH)D) levels and lipid profiles, including total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG).

In a cross-sectional analysis at the Yuhuan People's Hospital Physical Examination Center, 1535 asymptomatic individuals underwent anthropometric assessment and blood sampling. Serum 25(OH)D levels were quantified by a chemiluminescent immunoassay, while lipid parameters were evaluated by an enzymatic method on a fully automated analyzer.

The mean serum 25(OH)D level of the participants was 49.6 ± 15.3 nmol/L, with 54.7% demonstrating vitamin D deficiency. Female participants had significantly lower mean 25(OH)D levels (46.2 ± 13.7 nmol/L) than males (54.1 ± 16.0 nmol/L, P < 0.001). After adjustment for age and BMI, multivariate ordinal logistic analysis revealed a 1.71-fold higher dyslipidemia-associated risk of vitamin D deficiency in the population (OR=1.71, 95% CI=1.07-2.79), more pronounced in females(OR=2.84, 95% CI=1.17-8.09) compared to males (OR=1.44, 95% CI=0.82-2.58). Notably, vitamin D deficiency was significantly associated with elevated LDL-C levels in females (OR=5.17, 95% CI=1.47-32.96), in contrast to males.

This study highlights a significant association between 25(OH)D deficiency and an increased risk of dyslipidemia, especially in females, highlighting the importance of considering gender-specific risk factors in the management of 25(OH)D deficiency.

The Middle East and North Africa region are traditionally known as regions with a high prevalence of vitamin D deficiency. However, serum 25-hydroxyvitamin D (25OHD) levels seem to be increasing lately. We developed guidelines on the screening and supplementation of adult Lebanese patients with vitamin D. These guidelines address community-dwelling and institutionalized individuals.

Our guideline panel consisted of clinical and methodology experts that formulated the guidelines questions. We conducted a systematic review to gather global data on fracture (CRD42019129540), regional data on vitamin D trials (CRD42014010488), and on patients' values and preferences (CRD42022320022). We also complemented the latter with results from a cross-sectional local study. We followed the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology to assess the quality and certainty of evidence, and to develop recommendations.

For community-dwelling and institutionalized Lebanese adult population, the panel suggests no screening for vitamin D deficiency, over screening for vitamin D deficiency (conditional recommendation, based on very low certainty evidence). For community-dwelling Lebanese adult population, the panel suggests no supplementation with calcium and vitamin D, over supplementation (conditional recommendation, based on moderate certainty evidence). For institutionalized Lebanese adult population, the panel suggests supplementation with calcium and vitamin D, over no supplementation (conditional recommendation, based on moderate certainty evidence). The guidelines also identify high-risk subgroups, more likely to benefit from screening and supplementation. In community dwelling and institutionalized Lebanese adult individuals, for whom there is a decision to supplement with calcium and vitamin D, the panel suggests supplementation with a daily vitamin D equivalent of 600-2000 IU, as compared to doses higher than 2000 IU (conditional recommendation, very low certainty evidence).

The Lebanese GRADE-based vitamin D guidelines recommend against population screening and vitamin D supplementation. Subgroups at high risk are identified. The guidelines take into account contextual factors, and allow their adoption or adaptation in countries in the region.

Asians, especially Chinese have an increasingly high prevalence of vitamin D deficiency and insufficiency (serum 25-hydroxy-vitamin D 25(OH)D < 30 nmol/L and < 50 nmol/L, respectively). This population group also has a high prevalence of cardiometabolic risk factors such as Myocardial Infarction (MI), Metabolic Syndrome (MetS) and low blood levels of high-density lipoproteins (HDL) and high blood levels of triglycerides (TG). The aim of this analysis was to investigate these associations in a population from Macau, China. Blood, anthropometric, and physical data were collected from 1410 randomly selected residents of Macau. In this population, (55 % female, 19-89 years) 54 % were vitamin D insufficient. Results from categorical multivariate regression analyses (adjusted for age, sex, and physical activity, sitting and sunlight exposure) indicated significant two-fold associations between vitamin D insufficiency and prevalence of MI, MetS and low HDL and high TG levels. These associations became stronger when investigated with vitamin D deficiency (25(OH)D < 30 nmol/L). The association between cardiometabolic factors and vitamin D deficiency in those older (≥60 yrs) increased markedly to OR MI= 9.48 (2.62-34.32), OR MetS= 7.82 (3.31-18.46) and OR low HDL= 8.68 (1.56-21.16) and OR high TG= 2.37 (1.07-5.25). These interesting observational findings suggest high vulnerability to lower 25(OH)D levels with related health disparities affecting older Asians. Integration of public health measures to detect vitamin D deficiency and insufficiency in Macau is important, and we suggest that routine health screening including serum 25(OH)D, HDL and TG in China may be protective for those at higher risk for related cardiometabolic conditions.

This research seeks to thoroughly examine the present state and research hotspots in Mendelian randomization (MR) in osteoporosis (OP)-related fields, providing a reference for future research directions in this area. Following an exhaustive search of the Web of Science Core Collection database, our analysis utilized citation statistics for osteoporosis studies conducted from January 1, 2007, through March 15, 2024. Bibliometric and visual analyses were conducted using two online analysis systems, CiteSpace and VOSviewer. The analysis included a variety of dimensions, including the distribution of citations, authorship, published journals, year of publication, countries, co-occurrence keywords and keyword clustering. From 2007 to 2024, the number of publications in MR in OP-related fields showed an overall increased. High-impact publications and leading contributors were primarily from China, followed by the USA and England. The journal with the largest number of publications in MR in OP-related fields is the Journal of Bone and Mineral Research. Risk factor research, genome-wide associations, meta-analysis, fractures, and gene loci were the main research hotspots. Interdisciplinary integration, MR research combined with data from clinical trials and observational studies, represents the future development trend. Research on MR in OP-related fields has mainly been conducted in China, the USA, and England. The research hotspots were aimed at exploring the causative between risk factors and OP. Future studies are likely to center on multidisciplinary integration.

Vitamin D is crucial for normal organ function, vascular health and exercise performance, yet its deficiency is widespread. Patients with CHD often exhibit reduced exercise capacity. Limited research exists on vitamin D in CHD.

This study investigates serum 25-hydroxy vitamin D levels in 55 adult CHD patients (median age 31 years) compared to 55 age- and gender-matched controls without cardiac disease and examines associations with exercise capacity, peripheral microvascular function, muscle strength and biventricular function in CHD. Therefore, patients underwent fingertip arterial tonometry, transthoracic echocardiography, muscle strength measurements and cardiopulmonary exercise testing.

Results indicated that 93% of CHD patients and 91% of controls had 25-hydroxy vitamin D levels <30 ng/ml, with both groups showing varying values depending on the season in which the studies were conducted. No significant difference in 25-hydroxy vitamin D levels was found between patients and controls. While vitamin D levels in CHD patients did not significantly correlate with age, body mass index, blood pressure, peripheral microvascular function, high-sensitivity C-reactive protein, cholesterol levels, N-terminal-pro hormone B-type natriuretic peptide, ventricular function or muscle strength, a significant correlation was found with percent-predicted peak oxygen consumption (ρ=0.41, p = 0.005 and ρ=0.34, p = 0.02 for reference values following Wasserman and the LowLands registry, respectively), even after adjusting for season (p = 0.03 and 0.05, respectively).

In conclusion, vitamin D levels were similar between CHD patients and controls, but vitamin D insufficiency is common and linked to reduced exercise capacity in CHD. Further research is needed to determine whether vitamin D supplementation combined with exercise could be beneficial in CHD with vitamin D insufficiency.

Vitamin D deficiency is common in patients with chronic kidney disease (CKD) and associates with poor outcomes. Current clinical practice guidelines recommend supplementation with nutritional vitamin D as for the general population. However, recent large-scale clinical trials in the general population failed to demonstrate a benefit of vitamin D supplementation on skeletal or non-skeletal outcomes, fueling a debate on the rationale for screening for and correcting vitamin D deficiency, both in non-CKD and CKD populations. In a collaboration between the European Renal Osteodystrophy initiative of the European Renal Association (ERA) and the European Society for Paediatric Nephrology (ESPN), an expert panel performed an extensive literature review and formulated clinical practice points on vitamin D supplementation in children and adults with CKD and after kidney transplantation. These were reviewed by a Delphi panel of members from relevant working groups of the ERA and ESPN. Key clinical practice points include recommendations to monitor for, and correct, vitamin D deficiency in children and adults with CKD and after kidney transplantation, targeting 25-hydroxyvitamin D levels >75 nmol/l (>30 ng/ml). Although vitamin D supplementation appears well-tolerated and safe, it is recommended to avoid mega-doses (≥100 000 IU) and very high levels of 25 hydroxyvitamin D (>150-200 nmol/l, or 60-80 ng/ml) to reduce the risk of toxicity. Future clinical trials should investigate the benefit of vitamin D supplementation on patient-relevant outcomes in the setting of vitamin D deficiency across different stages of CKD.

The role of vitamin D in the prevention of colorectal cancer (CRC) has been the focus of research, but the results of relevant studies are not entirely consistent. While most studies indicate that vitamin D has a protective effect against CRC, there are also research reports stating that at high serum levels, there is no significant association between vitamin D and CRC, or even an increased risk. Additionally, there are still differences in the recommended serum 25-hydroxyvitamin D [25(OH)D] concentrations among various guidelines or committees. This study examined the association between serum 25-hydroxyvitamin D concentrations and the risk of CRC in US adults.

This study included 43,678 adult participants from the National Health and Nutrition Examination Survey (NHANES) 2001-2018, and logistic regression modelling was used to examine the association between serum 25(OH)D concentrations and the risk of CRC. We grouped participants according to the classification criteria of the various guidelines available for vitamin D, and controlled for confounding using a multi-model strategy, adjusting for key covariates such as gender, age, race, education level, marital status, family income to poverty ratio (PIR), body mass index (BMI), smoking habits, drinking habits, diabetes, hypertension, dyslipidemia, calcium intake, and total folate intake. We also performed trend tests to evaluate the linear relationship between serum 25(OH)D concentrations and CRC risk, used restricted cubic spline (RCS) plots to assess the dose-response relationship, and conducted further subgroup analyses with interaction tests to examine potential variations in the association across different population groups. We focused on the association between serum 25(OH)D concentration ≤ 75 nmol/L and CRC, again using multivariable logistic regression with a multi-model strategy and RCS plots.

A total of 43,382 participants without CRC and 296 participants with CRC were included in this study. In the fully adjusted model, participants with serum 25(OH)D < 50 nmol/L had more than twice the risk of developing CRC compared to those with levels of 50-< 75 nmol/L (<30 nmol/L: Odds Ratio [OR] = 2.038, 95% Confidence Interval [CI]: 1.011-4.109; 30- < 50 nmol/L: OR = 2.090, 95% CI: 1.361-3.211). The negative correlation between serum 25(OH)D concentration and the risk of CRC was significant when serum 25(OH)D concentration was ≤ 75 nmol/L (P < 0.001). Each 1 nmol/L increase in serum 25(OH)D concentration was associated with an approximately 2.3% reduction in the risk of CRC (95% CI: 0.964-0.990).

Our findings indicate a strong inverse association between serum 25(OH)D concentrations and the risk of CRC, particularly when levels are ≤75 nmol/L. Maintaining serum 25(OH)D above 75 nmol/L is associated with a lower CRC risk and may serve as a cost-effective preventive strategy. Public health measures, including routine vitamin D screening in high-risk populations and targeted supplementation, could further support CRC prevention efforts.

We aimed to estimate the prevalence of vitamin D deficiency in Mongolian men aged from 15 to 49 years at the National level as part of the Fifth National Nutrition Survey in 2016. This was a cross-sectional survey, conducted between September and November in 21 aimags of 4 economic regions of the country, and also in Ulaanbaatar. Given the regional differences in lifestyle and nutritional status, the target populations were stratified into 5 strata based on their economic region and in Ulaanbaatar, with equal samples drawn from each stratum using a cluster-randomized sampling design. A representative sample of 30 clusters [villages] was randomly selected using Probability Proportional to Size [PPS] methodology in each of the 4 regions and in Ulaanbaatar for a total of 150 cluster units. The selection of survey participants differed for the three sampling regions. Household eligibility was based on having a child 0-59 months of age, living in the household which was randomly selected from each cluster for a total of 450 households in each region. Households with a child 0-59 months of age were selected from household lists available at the kheseg or bagh level. All men 15-49 years of age who resided in the selected households were also eligible to participate in the survey. Serum concentration of 25-hydroxyvitamin D [25(OH)D] were measured using an enzyme-linked fluorescence assay in 377 men aged 15-49 years. The overall mean serum level of 25(OH)D concentration was 22.26 ± 0.48 ng/mL (95 % CI 21.31-23.21). The mean serum 25(OH)D concentrations were 19.65 ± 0.32 ng/mL (95 % CI19.01-19.82), and 33.68 ± 0.49 ng/mL (95 % CI 32.72-34.64) in vitamin D deficient, and in vitamin D sufficient subjects, respectively. The prevalence of vitamin D deficiency was 83.5 % with no significant difference in the prevalence of vitamin D deficiency by age group, economic region, area, location, education, and wealth index quintile. The prevalence of men in this study who were overweight or obese was 48.8 % and 14.6 % respectively. Although no significant difference was found between vitamin D deficiency and obesity, vitamin D deficiency was higher among men aged 30-39 and 40-49 years old by age specific analyses. The men did not take vitamin D supplements, and there is currently no vitamin D food fortification in Mongolia. The findings of this survey showed that vitamin D deficiency in men is a public health problem in Mongolia. In conclusion, vitamin D deficiency are common in Mongolian men, which indicates the need for vitamin D screening and treatment, as well as for an increased use of vitamin D supplements and for implementing vitamin D food fortification programs.

Vitamin D was discovered as the cure for nutritional rickets, a disease of bone growth arising from inadequate intestinal calcium absorption, and for much of the 20th century, it was studied for its critical role in calcium homeostasis. However, we now recognize that the vitamin D receptor and vitamin D metabolic enzymes are expressed in numerous tissues unrelated to calcium homeostasis. Notably, vitamin D signaling can induce cellular differentiation and cell cycle arrest. Moreover, the vitamin D receptor and the enzyme CYP27B1, which produces the hormonal form of vitamin D, 1,25-dihydroxyvitamin D (1,25D), are expressed throughout the immune system. In addition, CYP27B1 expression in immune cells is regulated by physiological inputs independent of those controlling its expression in calcium homeostatic tissues. These observations have driven the development of 1,25D-like secosteroidal analogs and nonsecosteroidal analogs to separate the effects of vitamin D on cell differentiation and function from its calcemic activities. Notably, some of these analogs have had considerable success in the clinic in the treatment of inflammatory and immune-related disorders. In this review, we described in detail the mechanisms of vitamin D signaling and the physiological signals controlling 1,25D synthesis and catabolism, with a focus on the immune system. We also surveyed the effects of 1,25D and its analogs on the regulation of immune system function and their implications for human immune-related disorders. Finally, we described the potential of vitamin D analogs as anticancer therapeutics, in particular, their use as adjuncts to cancer immunotherapy. SIGNIFICANCE STATEMENT: Vitamin D signaling is active in both the innate and adaptive arms of the immune system. Numerous vitamin D analogs, developed primarily to minimize the dose-limiting hypercalcemia of the active form of vitamin D, have been used widely in preclinical and clinical studies of immune system regulation. This review presents a description of the mechanisms of action of vitamin D signaling, an overview of analog development, and an in-depth discussion of the immunoregulatory roles of vitamin D analogs.

Besides its classical skeletal function, vitamin D plays a critical role in both skeletal muscle and the immune system. Interleukin-15 (IL-15), which is highly expressed, and secreted complexed with its receptor, IL-15Rα, by skeletal muscle, stimulates the development of immune cells and affects myogenesis and muscle mass. However, little is known about possible regulators of this myokine. To test whether vitamin D could be a regulator of muscle IL-15 and IL-15Rα expression, C2C12 myotubes were treated with vitamin D3 metabolites and analysis were performed in gastrocnemius muscles of rats treated with a single intraperitoneal dose of 1,25(OH)2D3. The role of VDR was investigated by siRNA technique in C2C12 myotubes and in gastrocnemius muscles of vitamin D receptor knockout (Vdr-KO) mice. Treatment of C2C12 myotubes with 1,25(OH)2D3 or 25(OH)D3 increased Il-15 gene expression in a dose-dependent manner and 1,25(OH)2D3 also moderately increased the relative Il-15 protein amount. Rats treated with a single dose of 1,25(OH)2D3 demonstrated a higher mRNA abundance of muscle Il-15 than controls. The 1,25(OH)2D3 effect on Il-15 was considerably weaker in C2C12 myotubes treated with Vdr-specific siRNA. Vdr-KO mice showed significantly lower muscle Il-15 mRNA than WT mice. Il-15Ra mRNA and Il-15/Il-15Rα protein abundance were unaffected by 1,25(OH)2D3-treatment or VDR functionality, and Cyp27b1 activity is not required for 25(OH)D3-mediated Il-15 gene expression. The results provide evidence for a regulatory role of hydroxyvitamin D3 metabolites on the Il-15 synthesis in skeletal muscle cells, which is largely mediated by the VDR.

Background/Objectives: Vitamin D-crucial for bone health, immune function, and hormone regulation-is deficient worldwide, affecting around half the population, particularly women. The study aims to determine the prevalence and risk factors of vitamin D deficiency and hypovitaminosis D in non-pregnant women in Lebanon. Methods: A national cross-sectional survey sampled households across Lebanon, covering 2803 non-pregnant women aged 15 to 49. Demographic information and dietary habits were collected, and anthropometric measurements and serum analyses, including 25-hydroxyvitamin D (25(OH)D) concentrations, were conducted. Multivariable Poisson regressions were constructed to calculate the adjusted prevalence ratio (aPR) for vitamin D deficiency and hypovitaminosis D of variables. Results: The prevalence of vitamin D deficiency (<30 nmol/L) among non-pregnant women in Lebanon was 37.9%, while 69.2% had hypovitaminosis D (<50 nmol/L). Wearing a veil (hijab) was identified as the most significant risk factor for both vitamin D deficiency (aPR = 3.76) and hypovitaminosis D (aPR = 1.47). Additionally, olive skin and dark skin were both associated with an increased prevalence of vitamin D deficiency (olive skin: aPR = 1.14; dark skin: aPR = 1.28), while only dark skin color was associated with hypovitaminosis D (aPR = 1.10). In contrast, protective factors against vitamin D deficiency and hypovitaminosis D included daily sun exposure exceeding one hour (aPR = 0.83-0.91) and vitamin D supplementation (aPR = 0.30-0.55). Anemia, folate deficiency, and vitamin B12 deficiency were significantly associated with a higher prevalence of vitamin D deficiency, hypovitaminosis D, or both. BMI was not significantly associated with vitamin D deficiency; however, women with underweight (aPR = 1.13) and obesity (aPR = 1.12) exhibited a higher prevalence of hypovitaminosis D. Conclusions: Vitamin D deficiency and hypovitaminosis D affect a significant portion of non-pregnant women in Lebanon, with veiling (hijab wearing), limited sun exposure, and lack of supplementation as primary risk factors. Future work should focus on tailoring recommendations for vitamin D supplementation, sun exposure, and food fortification to effectively address the diverse risk factors in the population.

Background and Objectives: Adequate levels of vitamin D are vital for both growth and immunomodulation in children. To evaluate the levels of vitamin D in children from Western Romania and to identify significant age, seasonal, and geographical disparities. Materials and Methods: This study evaluates the level of 25-hydroxyvitamin D levels assessed on Cobas 6000's module e601 in 1698 children aged 1-18 years between 1 January 2018 and 31 December 2021 from Western Romania. Results: Children aged 1-6 years predominantly present sufficient levels (>30 ng/mL), while older age groups showed a marked decline. Adolescents aged 13-18 years were most affected, with over half displaying insufficient levels (20-30 ng/mL). Rural children were more likely to achieve sufficiency compared to urban peers. Males demonstrated significantly higher vitamin D levels when compared to females. Seasonal variations showed the highest vitamin D levels during late summer and early autumn (September: aOR = 5.47; 95% CI: 3.17-9.42, p < 0.001). Multivariate analysis revealed a significant improvement in vitamin D levels during 2019-2020. Conclusions: Our findings suggest the need for targeted screening programs and health policies to address vitamin D deficiency, particularly among older children, urban residents and during winter months.

Vitamin D plays a crucial role in bone health, calcium absorption, and immune function, yet significant misconceptions and knowledge gaps persist. This study aimed to assess knowledge regarding vitamin D among Greek women and identify factors associated with vitamin D knowledge.

A cross-sectional study was conducted among 761 Greek women (mean age: 41.2 ± 7.7 years) using an online self-administered questionnaire designed in Google Forms. Participants were recruited via social media platforms to ensure a geographically diverse sample.

Overall, 57.4% of participants demonstrated knowledge of vitamin D's functions, primarily linking it to bone health (34.4%) and immune function (26.8%). The multiple regression model identified significant predictors of knowledge of vitamin D's functions, including age (OR = 1.041, 95% CI: 1.019-1.062, p < 0.001), weight (OR = 0.964, 95% CI: 0.938-0.992, p = 0.010), and frequent vitamin D testing (>2 times: OR = 2.280, 95% CI: 1.392-3.736, p = 0.001; once-twice: OR = 1.776, 95% CI: 1.111-2.829, p = 0.016). Furthermore, age (OR = 1.054, 95% CI: 1.027-1.081, p < 0.001), weight (OR = 0.987, 95% CI: 0.975-0.999, p = 0.028), higher city population (>50,000 citizens: OR = 1.598, 95% CI: 1.021-2.502, p = 0.040), frequent vitamin D testing (>2 times: OR = 2.616, 95% CI: 1.529-4.447, p < 0.003; one-two times: OR = 1.773, 95% CI: 1.052-2.989, p = 0.032), and children's supplementation (OR = 1.414, 95% CI: 1.007-1.987, p = 0.046) were significant predictors of knowledge regarding diseases preventable by vitamin D.

Greek women demonstrated moderate awareness of vitamin D's functions, but significant knowledge gaps persist, particularly regarding its role in calcium absorption and dietary sources. Age, frequent vitamin D testing, and urban residence were significant predictors of knowledge. Targeted public health campaigns are essential to address misconceptions and improve vitamin D awareness and practices.

Roughly 90% of the Polish population experiences vitamin D deficiency. The 3-epi-25(OH)D2 and 3-epi-25(OH)D3 are stereoisomers of 25(OH)D2 and 25(OH)D3, and they can inadvertently be included in measurements of 25(OH)D levels, potentially leading to its overestimating. We aimed to measure 25(OH)D2 and 25(OH)D3, their epimers 3-epi-25(OH)D2 and 3-epi-25(OH)D3, and biologically active 1,25(OH)2D3 in patients with cardiovascular disease and healthy volunteers. We enrolled 27 adult patients with cardiovascular disease (64 ± 15 years) and 35 healthy volunteers (36.37 ± 12.29 years). We used a validated ultra-performance liquid chromatography-mass spectrometry/mass spectrometry (UPLC-MS/MS) method to measure 25(OH)D2/3 concentrations and their epimers. Plasma concentrations of 1α,25(OH)2D3 were determined by sensitive and quantitative enzyme immunoassay following intra- and inter-day validation. Vitamin D insufficiency was observed in approximately 52% of the patients and 37% of healthy volunteers. Comparable levels of 25(OH)D3 and 25(OH)D2 were seen in both groups. The observed levels of the epimeric form 3-epi-25(OH)D3 appeared approximately 1.7 times higher in healthy volunteers, accounting for 9% misclassified according to vitamin D status. Also, patients had lower concentrations of 1,25(OH)2D3, and their 3-epi-25(OH)D2 levels were below the detection limit (2 ng/mL). In all studied subjects, 25(OH)D3 was negatively correlated with % 3-epi-25(OH)D3 (R=-0.758; P<0.001), and 3-epi-25(OH)D2 was negatively correlated with % 3-epi-25(OH)D2 (R = -0.842; P = 0.002). While the mechanism of how vitamin D epimeric forms influence diseases remains unclear, we recommend maintaining 25(OH)D3 levels above 20 ng/mL.

Objectives: To investigate the correlation between baseline serum concentrations of 25-hydroxyvitamin D (25-OHD) and quality of life (QoL), as well as pain perception in patients with chronic pain with long-term prescription opioid usage before opioid detoxification. Methods: We prospectively studied 45 patients with chronic pain with long-term prescription opioid usage who were selected for elective detoxification. Baseline serum 25-OHD levels were measured prior to detoxification, classifying patients as either vitamin D deficient (<75 nmol/L) or sufficient (≥75 nmol/L). QoL was assessed using the SF-36v2TM questionnaire, while pain levels were assessed using Visual Analogue Scale (VAS) scores before treatment. Results: Mean pain scores before detoxification of the patients with sufficient baseline 25-OHD levels vs. those with deficient levels were, respectively, 6.06 ± 2.32 vs. 6.86 ± 2.10 (normalized scores 1.22 ± 0.571 vs. 0.950 ± 0.632; p = 0.164). The analysis of SF-36v2™ questionnaire scores revealed minimal variation between groups (35.00 ± 14.198 vs. 34.97 ± 13.52), indicating no significant association between Vitamin D levels and QoL (p = 0.913). Conclusions: The analysis of baseline 25-OHD levels in relation to QoL assessments and pain scores did not reveal a statistically significant association, indicating that variations in baseline vitamin D levels may not substantially impact QoL or pain perception. Further studies may help determine how to assess and optimize vitamin D levels in patients with chronic pain on long-term prescription opioids.

Rett syndrome (RS) is a rare neurodevelopmental disorder primarily caused by mutations in the X-linked methyl-CpG binding protein 2 (MECP2) gene, responsible for encoding MECP2 which plays a pivotal role in regulating gene expression. The neurological and non-neurological manifestations of RS vary widely in severity depending on the specific mutation type. Bone complications, mostly scoliosis but also osteoporosis, hip displacement, and a high rate of fractures, are among the most prevalent non-neurological comorbidities observed in girls with RS. Low bone mineral density (BMD) is primarily due to a slow rate of bone formation due to dysfunctional osteoblast activity. The use of anticonvulsants, immobilization, low physical activity, poor nutrition, and inadequate vitamin D intake all significantly hamper skeletal maturation and the accumulation of bone mass in RS girls, making them more susceptible to fragility fractures. In RS patients, the upper and lower limbs are the most common sites for fractures which are due to both a reduced BMD and a diminished bone size. This review summarizes the knowledge on risk factors for fragility fracture in patients with RS and proposes a potential diagnostic and therapeutic pathway to enhance low BMD and mitigate the risk of fragility fractures. In particular, this review focused on the importance of clinical and instrumental evaluation of bone status as a basis for adequate planning of nutritional, pharmacological, and surgical interventions to be undertaken. Additionally, the management of bone defects in individuals with RS should be customized to meet each person's specific needs, abilities, and general health.

Vitamin D deficiency is a global health issue linked to various chronic diseases and overall mortality. It primarily arises from insufficient sunlight exposure, compounded by dietary limitations. Vitamin D fortification of commonly consumed foods has emerged as a viable public health intervention to address this deficiency. This review evaluates the impact of vitamin D food fortification on serum levels, intake, and health outcomes and explores the stability, bio-accessibility, bioavailability, and cost-effectiveness of such interventions. A comprehensive literature search was conducted in PubMed and Google Scholar, focusing on studies from 2015 to 2024. The criteria included primary research on healthy adults that addressed the effects of vitamin D fortification on health, intake, and serum levels, as well as the fortification's stability, bio-accessibility, bioavailability, and cost-effectiveness. Studies were extracted and analyzed according to PRISMA guidelines. The review included 31 studies from diverse geographic locations, revealing that fortifying dairy products, cereals, fats, oils, and other food items effectively increased serum 25-hydroxyvitamin D levels. The fortification methods varied, with vitamin D3 showing superior efficacy over vitamin D2. Encapsulation techniques improved stability and bioavailability. Fortifying staple foods like milk and eggs proved cost-effective compared with pharmaceutical interventions. Vitamin D food fortification significantly enhances serum levels and intake, with dairy and cereals being the most frequently fortified. Standardized fortification guidelines are essential to ensure safety and efficacy. Ongoing evaluation and region-specific policies are crucial for effectively optimizing fortification strategies and addressing vitamin D deficiency.

Background: The condition of vitamin D (25OHD) deficiency represents an important public health problem. In Europe, hypovitaminosis is common not only in the elderly population but also between 50 and 70 years, both in males and females. Data regarding vitamin D intake in the Italian population are very limited. In a recent paper, reporting data collected by a specific Frequency Food Questionnaire (FFQ), we observed in a small group of healthy subjects that the dietary consumption of vitamin D, both in females and males, was far below the average. Methods: With the aim of expanding our preliminary data, we conducted a survey on a large cohort of subjects from different areas of Northern, Central, and Southern Italy. The FFQ contained 11 different questions regarding the amount and type of intake of foods containing ergocalciferol and cholecalciferol. It was submitted to 870 subjects, 627 females and 243 males, with an age range from 40 to 80 years; 31.6% of the studied population was apparently in good health, while 68.4% were affected by different pathologies. Results: The present data confirm previous observations: the global quantity of vitamin D intake in 14 days was 70.8 μg (±1.8 SE, ±54.4 SD) in females and 87.5 μg (±1.9 SE, ±57.1 SD) in males; the mean daily intake of vitamin D in females and males was 5.05 μg (±0.5 SE, ±3.8 SD) and 6.25 μg (±0.21 SE, ±4.1 SD), respectively. In healthy subjects, a gradual decrease was observed in the overall intake of vitamin D in both females and males according to an increase in age bracket, ranging from 74.5 μg and 103.8 μg in the 40-50 age group to 54.5 μg and 87.8 μg in the 71-80 age group, respectively. Conclusions: In conclusion, the present data, collected in a large Italian cohort, underscore that the daily intake of vitamin D is far below the recommended daily average, thereby contributing to the development of potential hypovitaminosis.

To use the prevalence of prenatal/infancy interglobular dentine (IGD) as a proxy for suboptimal vitamin D status and explore its link to mortality, biological sex, cultural behaviours and environmental factors during the end of the pre-industrial/ beginning of the industrial period.

50 skeletons from the St. Antoine cemetery (1799-1854), Montreal, Quebec with a well-preserved first mandibular molar.

Thin sections were prepared for histological examination of IGD in crown dentine.

IGD prevalence was 74 % (37/50) and not significantly correlated statistically to sex and age-at-death. Most IGD occurred at birth and up to 3 years-old, six individuals were affected in utero, 54 % of the sample (27/50) presented longstanding IGD and six individuals displayed multiple IGD episodes.

Prenatal IGD episodes revealed suboptimal maternal vitamin D levels, which, alongside a high frequency of IGD episodes around birth/from birth until a certain age, suggest cultural influences. Multiple and longstanding IGD episodes might also reflect suboptimal seasonal vitamin D attainment.

This study provides in-depth data on IGD within a relatively large archaeological North American sample, proving relevant to epidemiological studies on suboptimal vitamin status in 19th century Montreal.

The total number of IGD episodes is underestimated due to methodological biases; first-generation migrants in this study could not be identified and excluded from the sample.

Use of a larger sample with a wider age-at-death range; further research on infants and children to investigate links between growth and lesion formation and visibility.

The teenage years represent a crucial period of physical and cognitive growth and development with sufficient micronutrient intakes necessary to meet high nutritional requirements. This review examines current micronutrient intakes in teenagers in the Western world in the context of public health implications including the prevalence of inadequate intakes and risk of excessive intakes. Intakes of vitamins A, D, E and C, folate, calcium, iron, magnesium, zinc and potassium in teenagers are low when compared to generally accepted recommendations, while there is little risk of excessive micronutrient intakes based on current dietary patterns. Therefore, strategies should focus on increasing micronutrient intakes in order to decrease the risk of negative impacts resulting from these low intakes. These strategies should be mindful of guidance towards an environmentally sustainable diet whilst ensuring that nutrient intakes in teenagers are not further negatively impacted. In order to identify, implement and monitor the effectiveness of such strategies, intakes of micronutrients should be continually monitored in nationally representative samples of the population for all age groups including this vulnerable cohort of teenagers.

CYP24A1 is a crucial gene within the cytochrome P450 superfamily, responsible for encoding the enzyme 25-hydroxyvitamin D3-24-hydroxylase. This enzyme is involved in the catabolism of 1,25-dihydroxyvitamin D3, the biologically active form of vitamin D3, by hydroxylating its side chain. Through this process, CYP24A1 tightly regulates the bioavailability and physiological impact of vitamin D3 in the body. Dysregulation of CYP24A1, particularly its overexpression, has been increasingly associated with the progression of various diseases, including cancers, autoimmune disorders, and chronic inflammatory conditions. Elevated levels of CYP24A1 can lead to excessive degradation of vitamin D3, resulting in diminished levels of this critical hormone, which is essential for calcium homeostasis, immune function, and cellular proliferation. This review explores into the structural characteristics of CYP24A1, exploring how it influences its enzymatic activity. Furthermore, it examines the expression patterns of CYP24A1 across different diseases, emphasizing the enzyme's role in disease pathology. The review also discusses the regulatory mechanisms governing CYP24A1 expression, including genetic mutations, epigenetic modifications, and metabolite-mediated regulation. By understanding these mechanisms, the review provides insight into the potential therapeutic strategies that could target CYP24A1, aiming to alleviate its overexpression and restore vitamin D3 balance in disease states.

Available epidemiological data on vitamin D status in the Ukrainian population are limited.

The aim of this study is to investigate the prevalence of vitamin D deficiency in Ukraine.

This multicentre cross-sectional study included a total of 11,462 participants: 1530 children with a median age 10 years, (IQR 6-14) and 56.21 % of them were female; 9932 adults with a median age of 36 years (IQR 26-48) and 78.72 % of them were female. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured once by chemiluminescent immunoassay (UniCel DxI 800 Access Immunoassay System, Beckman Coulter Inc., USA) in the period of January-December 2021 in Kyiv and Kyiv Oblast. The cut-offs were: vitamin D deficiency, <50 nmol/L; moderate deficiency, 25-<50 nmol/L; severe deficiency, <25 nmol/L; vitamin D insufficiency, 50-<75 nmol/L; vitamin D sufficiency, 75-<250 nmol/L; optimal concentration, 75-<125 nmol/L; increased levels, 125-<250 nmol/L; and toxicity, ≥250 nmol/L.

The median 25(OH)D level was 65.4 nmol/L (IQR 49.5-85.6) among all participants, severe vitamin D deficiency was recorded in 2.9 % of participants (95 % CI: 2.6-3.2), moderate deficiency in 23 % (95 % CI: 22-24), and vitamin D insufficiency in 37 % (95 % CI: 36-38).Prevalence of vitamin D deficiency in group 1-17 years was 23.5 % (95 % CI: 21-26). We did not find vitamin D deficiency in children aged 1-2 years; however toxic levels were recorded in 4.2 % of the children in this age group (95 % CI: 1.4-9.6). Among the adults (≥18 years old), prevalence of vitamin D deficiency was 26 % (95 % CI: 25-27).

Vitamin D deficiency and insufficiency are common in Ukraine.

Background/Objectives: A significant number of patients experience prolonged symptoms following COVID-19 in particular cases of fatigue. Yet, pathomechanisms of COVID-19-related fatigue remain unclear. Methods: This study investigated patients after confirmed SARS-CoV-2 infection (PC) with relevant fatigue according to the Fatigue Assessment Scale (≥22 points) to rule out malnutrition as a driving factor for fatigue and to evaluate daily activity and sleep characteristics. Dietary behavior was recorded through food diaries and physical activity by self-reported (questionnaires) and objective (activity tracker) outcomes. Data were collected over a 7-day period and compared with a healthy control group (HC). A subgroup analysis of patients with fatigue and severe fatigue, as well as a sex-specific analysis, were included. Results: No significant differences in dietary intake were observed, but an indication toward a healthier Mediterranean diet in PC patients with a median Mediterranean Diet Score of 4 (IQR 3, 5) in HC vs. 5 (IQR 3, 6) in PC (p = 0.24). There were also no differences in physical activity, either by objective or subjective measures. However, the median sleep duration was 49 min longer in PC patients (p = 0.003). Conclusions: In conclusion, malnutrition did not significantly contribute to fatigue, yet patients with COVID-19-related fatigue showed increased sleep duration. As sleep characteristics play a crucial role in mental and physical wellbeing, the association of sleep, physical activity, and fatigue should be evaluated in further studies.

The aim of our research was to evaluate and analyze serum 25(OH) vitamin D and parathyroid hormone (PTH) levels to investigate whether vitamin D deficiency serves as a risk factor for an increased incidence of acute respiratory infections (ARI) in children. Serum PTH levels were used as an indicator of vitamin D sufficiency, as normal PTH levels require an optimal concentration of 25(OH) vitamin D. The study included 129 children, divided into five subgroups: children with acute bronchopneumonia (n = 42), acute laryngotracheitis (n = 7), acute bronchiolitis (n = 32), acute bronchitis (n = 18), and a control group (n = 30). No statistically significant differences in 25(OH)D levels were observed between the overall population of children with ARI and the control group (p = 0.073). However, significant differences in 25(OH)D levels were identified between the control group and children with bronchopneumonia, acute bronchitis, and laryngotracheitis (p < 0.01, p < 0.05). Regarding PTH levels, statistical significance was found between the control group and the acute bronchiolitis group, due to the high percentage of children with hypervitaminosis in this subgroup. These results highlight the crucial role of vitamin D in the onset and progression of acute respiratory tract infections in children, emphasizing its impact on their overall respiratory health.

Vitamin D deficiency is common in many societies and causes rickets and non-skeletal disorders in children. There are no published data on vitamin D deficiency in Afghanistan. We, therefore, investigated the prevalence and associated factors of vitamin D deficiency in Afghan school children in Kandahar City, Afghanistan. This cross-sectional analytical study was conducted from September 2022 to April 2023 in 510 primary school students aged 6-15 years from six randomly selected schools. Data were analyzed by using descriptive statistics, Chi-square test, and multivariate logistic regression. Of the 510 enrolled children, 54.3% were boys and 91.8% were poor. The mean serum 25(OH)D concentration was 9.3 ng/mL. Vitamin D deficiency (< 20 ng/mL) was detected in 436/510 (85.5%) children that was severe in 267/510 (52.4%). By logistic regression analysis, independent factors for vitamin D deficiency were: (i) older age group 11-15 vs. 6 - 10 years, adjusted odds ratio (AOR) 2.8 (95% confidence interval 1.2-6.2), (ii) poverty AOR 2.0 (1.0-4.3), (iii) not doing outdoor physical activity AOR 4.8 (2.8-8.1), and (iv) daily sunlight exposure < 60 min AOR 2.2 (1.3-3.7). Although Kandahar is very sunny throughout the year, vitamin D deficiency is highly prevalent among school boys and girls, placing them at great risk of vitamin D-deficient rickets. More work is needed to define the country-wide prevalence of vitamin D deficiency to inform robust strategies of vitamin D supplementation, the provision of vitamin D-fortified food to the school children in Kandahar City and health education programs that can be conducted with the help of international organizations.

Vitamin D plays an important role in maintaining bone health with numerous benefits for extraskeletal health as well.

We aimed to assess the prevalence of vitamin D deficiency in children (0-18 years old) in a tertiary hospital in Romania between August 2019 and January 2024 and to investigate the role of adequate supplementation in this vulnerable population.

The serum 25(OH)D levels were measured using a chemiluminescence binding assay.

A total of 744 participants were included in this study: 396 female (53.23%) and 348 male (46.77%). The serum levels of 25(OH)D ranged between 2.2 and 125.4 ng/mL, with a mean value of 27.4 ng/mL and a median value of 23.5 ng/mL. According to the cutoff values for the definition of vitamin D status (severe deficiency: <10 ng/mL, deficiency: <20 ng/mL, insufficiency: 20-29 ng/mL, and sufficiency: ≥30 ng/mL), the sample consisted of 77 (10.34%) cases of severe deficiency, 221 (29.7%) cases of deficiency, 194 (26.07%) cases of insufficiency, and 245 (32.93%) cases of sufficiency. There were seven cases of hypervitaminosis D with values above 100 ng/mL. The mean values (and corresponding 95% confidence intervals, CIs) were as follows: 27.85 ng/mL [25.95-29.76] in the males, 22.45 ng/mL [25.12-28.82] in the females, 24.82 ng/mL [21.86-27.77] in the spring, 28.62 ng/mL [26.42-30.81] in the summer, 32.30 ng/mL [29.16-35.44] in the autumn, and 24.01 ng/mL [21.57-26.44] in the winter. We observed a notable decline in the serum 25(OH)D levels with age, with 82.08% of the children in the age group above 6 years old having serum 25(OH)D levels below 30 ng/mL. In obese subjects, a higher prevalence of hypovitaminosis D was observed compared to non-obese subjects, with a mean value of 19.54 [17.50-21.57] ng/mL in obese children versus 28.89 [27.39-30.40] ng/mL in normal weight children.

In our sample, the mean serum concentration of 25(OH)D was 27.4 ng/mL. Notably, 66.11% of the cases demonstrated varying degrees of hypovitaminosis D, with a significantly higher prevalence of 86.16% observed in the obese group. Healthcare providers should prioritize routine screening for vitamin D levels in pediatric patients with obesity to facilitate timely intervention and personalized supplementation strategies tailored to individual needs.

A recent survey study found that 400 IU/day vitamin D is the most common dose in United States neonatal intensive care units. Results of clinical trials are inconsistent, and, therefore, have not determined the optimal vitamin D dose for efficacy and safety in the neonatal intensive care unit. Future studies must consider the unique attributes of perinatal vitamin D metabolism and the potential role of vitamin D in immune function and organ development. IMPACT: Preterm infant vitamin D metabolism is a complex yet important area of research.

An Italian multidisciplinary working group discussed the current Italian scenario of osteoporosis management during a meeting and highlighted the essential role of calcium and vitamin D supplementation in the prevention of fragility fractures.

This paper aims to review and discuss data on calcium and vitamin D requirements and the role of combined calcium and vitamin D supplementation in the treatment of patients with osteoporosis.

The discussion of the experts covered literature data on calcium and vitamin D supplementation, gaps in the diagnosis and treatment of osteoporosis, and the role of the primary care physician in identifying and treating patients with osteoporosis. Articles for consideration were identified through PubMed searches using different combinations of pertinent keywords.

The discussion highlighted that insufficient calcium or vitamin D intake increases the risk of fragility fractures. The experts also drew attention to the essential role of calcium and vitamin D supplementation in achieving an anti-fracture effect and supporting the efficacy of anti-osteoporotic agents without increasing nephrolithiasis and cardiovascular risks. In addition, the discussion underlined the role of the primary care physician in the initial clinical approach to patients with osteoporosis.

The experts believe that efficient treatment for patients with osteoporosis should include calcium and vitamin D supplementation to achieve adequate levels that are able to inhibit the parathyroid hormone and bone resorption.

Worldwide, more immigrants experience vitamin D (vitD) deficiency than non-immigrants. Recommendations in current clinical practice guidelines (CPGs) concerning vitD are inadequate to address vitD deficiency among immigrants, and there are concerns regarding the quality of guidance in these CPGs.

This study aimed to identify and evaluate the quality of published CPGs addressing vitD and immigrants' health using the Appraisal of Guidelines for Research and Evaluation-II (AGREE II) tool and clarify the recommendations pertaining to vitD and immigrant populations in these CPGs.

We performed a systematic search to identify the most recent CPGs across various databases (Ovid MEDLINE ALL, Embase and Turning Research Into Practice), guideline repositories and grey literature. Two reviewers independently conducted study selection and data abstraction and evaluated the quality of the included guidelines using the AGREE II tool.

We identified 25 relevant CPGs; 21 focused on vitD and 4 covered immigrants' health. Around one-quarter of the included CPGs were high quality (≥60% in at least four of the six domains, including 'rigour of development'). The highest mean scores among the six AGREE II domains were for 'clarity of presentation' and 'scope and purpose'. About 4.8% (1/21) of the CPGs on vitD had immigrant-related recommendations. VitD recommendations were emphasised in one out of the four immigrant health CPGs (25%). CPGs covering immigrants' health and vitD were inadequately systematically appraised. Moreover, recommendations regarding vitD were insufficient to address the growing epidemic of vitD deficiency among immigrant populations.

The insufficient recommendations for vitD fail to address the rising vitD deficiency among immigrants, highlighting a critical gap in healthcare provisions. Urgent national and international efforts are needed to develop comprehensive CPGs, bridging research, policy and practice disparities. Future guidelines must prioritise routine vitD screening, supplementation protocols for vulnerable immigrant groups, and culturally appropriate interventions to improve health outcomes for immigrants globally.

CRD42021240562.

Dietary supplements with vitamin and calcium are recommended to nursing home residents in Denmark, but adherence to the recommendation is low. In a previous part of this study, we reported improved adherence by means of The Model for Improvement leading to increased awareness and change of workflows at two nursing homes. However, potential effects of this improved adherence are unknown.

The objective of this substudy was to investigate if the improved adherence to the recommendation affected vitamin D status, muscle strength, and physical functioning of the residents.

This was a 20-week quasiexperimental study involving 40 residents from two Danish nursing homes. Baseline and endpoint measurements took place in October 2021 and March 2022, respectively. Outcomes were number of residents taking vitamin D and calcium supplements; vitamin D status; handgrip strength; and physical functioning with timed-up-and-go test and 30-second chair stand test.

Prevalence of vitamin D supplement users increased from 45 to 78% (mean dose 41 μg) and of calcium supplement users from 40 to 72% (mean dose 769 mg) (both P=0.002). Among those having blood sampled at both baseline and endpoint (n = 30), mean vitamin D status increased from 66.6 ± 31.7 nmol/L to 82.8 ± 26.3 nmol/L (P < 0.001), and more residents were vitamin D sufficient at endpoint (90 vs. 63%, P=0.021). Endpoint vitamin D status among supplement users was 88.2 ± 22.2 nmol/L, which was higher compared to nonsupplement users (55.3 ± 30.4 nmol/L, P < 0.01). No effects were seen on muscle strength or physical functioning.

Increased supplementation with vitamin D using The Model for Improvement positively affected vitamin D status and prevalence of vitamin D sufficiency but did not affect muscle strength or physical functioning. Longer-term studies involving more residents are needed to investigate effects of improved adherence on these outcomes. This trial is registered with NCT04956705.